case study questions class 10 science how do organisms reproduce

Case Study Questions Class 10 Science Chapter 8 How Do Organisms Reproduce

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Case study Questions Class 10 Science Chapter 8  are very important to solve for your exam. Class 10 Science Chapter 8 Case Study Questions have been prepared for the latest exam pattern. You can check your knowledge by solving case study-based questions for Class 10 Science Chapter 8 How Do Organisms Reproduce

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In CBSE Class 10 Science Paper, Students will have to answer some questions based on  Assertion and Reason . There will be a few questions based on case studies and passage-based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.

How Do Organisms Reproduce Case Study Questions With Answers

Here, we have provided case-based/passage-based questions for Class 10 Science  Chapter 8 How Do Organisms Reproduce

Case Study/Passage-Based Questions

Question 1:

The male reproductive system consists of portions that produce the germ cells and other portions that deliver the germ cells to the site of fertilization. Testes are located outside the abdominal cavity in the scrotum because sperm formation requires a lower temperature than normal body temperature. It also has a role of secretion of male sex hormone which brings changes in appearance seen in boys at the time of puberty. Vas deferens unites with a tube coming from the urinary bladder. The urethra is a common passage for sperms and urine. The prostate gland and seminal vesicles add their secretions so that sperms are now in a fluid.

(i) Name the sex hormone associated with males. (a) Testosterone (b) Progesterone (c) Oestrogen (d) None of these

Answer: (a) Testosterone

(ii) Which of the following statements is incorrect ? (a) Sperms are present in a fluid (b) Fluid provides nutrition to sperms (c) Fluid makes easier transportation of sperms (d) Fluid helps to bind the sperms together

(iii) Testes are located outside the abdominal cavity in scrotum because (a) sperms formation requires higher temperature than body temperature (b) sperms formation requires lower temperature than body temperature (c) it is easier to transport sperms from the scrotum (d) None of these

Answer: (b) sperms formation requires lower temperature than body temperature

(iv) Which of the following statement is incorrect? (a) Sperms and urine has a common passage from urethra.

(b) Sperms have long tail that helps them to move forward. (c) Sperms contain genetic material. (d) Sperms formation requires 1–3°C higher temperature than normal body temperature.

Answer: (d) Sperms formation requires 1–3°C higher temperature than normal body temperature.

(v) What is the nature of semen? (a) slightly acidic (b) Neutral (c) Slightly basic (d) Strongly basic

Answer: (c) Slightly basic

Question 2:

Rohit collected some pond water which was dark green in color in a test tube. She took out green-colored mass from it and separated its filaments by using needles. She broke some filaments into small fragments and put them in a Petri dish containing clean water. She observed that after a few days the small fragments gave rise to complete filaments.

2.1) What do you think the mass of green filament was ?  (a) It was a mass of Spirogyra filament. (b) It was a colony of Volvox algae. (c) It was large brown algae. (d) It was a mass of fungal filaments

Answer:(a) It was a mass of Spirogyra filament. ​

2.2) Organisms that reproduces in similar ways as Spirogyra is : (a) yeast (b) hydra (c) Planaria (d) Sea anemone

Answer: (d) Sea anemone ​

2.3) The small fragment gave rise to new filament. What does it indicate  ? (a) Spirogyra reproduces asexually through budding. (b) Spirogyra reproduces asexually through spore formation. (c) Spirogyra reproduces asexually through fragmentation. (d) Spirogyra reproduces asexually through fission

Answer: (c) Spirogyra reproduces asexually through fragmentation. ​

2.4) Which among the following organisms do not reproduce by fragmentation ? (a) Riccia  (b) Selaginella (c) Aurelia (d) Marchantia

Answer: (c) Aurelia. ​

2.5) Select the correct statement from the following. (a) Only multicellular organisms can undergo fragmentation. (b) Both unicellular and multicellular organisms can undergo fragmentation. (c) Fragmentation is sexual mode of reproduction. (d) Fragmentation is found only in algae

Answer: (a) Only multicellular organisms can undergo fragmentation ​

Question 3:

In humans, if the egg is not fertilized, it lives for about one day. Since the ovary releases one egg every month, the uterus also prepares itself every month to receive a fertilized egg. Thus its lining becomes thick and spongy. This would be required for nourishing the embryo if fertilization had taken place. Now, however, this lining is not needed any longer. So, the lining slowly breaks and comes out through the vagina as blood and mucous. This cycle takes place roughly every month and is known as menstruation. It usually lasts for about two to eight days.

3.1) What is the sexual cycle in human female that takes place every 28 days and marked by bleeding ? (a) Sexual cycle (b) Reproductive cycle (c) Menstrual cycle (d) Blood cycle

Answer: (c) Menstrual cycle ​

3.2) If fertilisation takes place, it results in the formation of : (a) an embryo (b) a zygote (c) a foetus (d) a placenta

Answer: (b) a zygote ​​

3.3) Why does vaginal bleeding occur in human females on attaining puberty ? (a) Unfertilised egg along with thick uterus lining come out of vagina in form of bleeding. (b) In human females, ovaries start releasing egg or ovum once every 28 days from the age of puberty. (c)  If fertilisation does not occur then menstrual flow occurs at the end of cycle. (d) All of these 

Answer: (d) All of these  ​​​

3.4) In what conditions vaginal bleeding will not occur in a human female who has attained puberty ? (a) If the ovum is fertilised (b) If the ovum is not fertilised (c) If there is some hormonal imbalance in female (d) Both (a) and (b)

Answer: (d) Both (a) and (b)  ​​​

3.5) Mark one change from the following associated with sexual maturation in boys ? (a) loss of milk teeth (b) weight gain (c) increase in height  (d) cracking of voice

Answer: (d) cracking of voice ​​​

Question 4: A newly married couple does not want have children for few years. They consulted a doctor who advised them barrier method and chemical method of birth control. Yet another couple who already have two children and are middle aged also consulted doctor for some permanent solution to avoid unwanted pregnancy. Doctor advised them surgical method of birth control.

Another category of contraceptives acts by changing the hormonal balance of the body so that eggs are not released and fertilisation cannot occur. These drugs commonly need to be taken orally as pills. However, since they change hormonal balances, they can cause side-effects too. Other contraceptive devices such as the loop or the copper-T are placed in the uterus to prevent pregnancy. Again, they can cause side effects due to irritation of the uterus.

4.1) What are the barrier methods of birth control ? (a) Condoms (b) Oral pills (c) Surgery (d) Both (a) and (c)

Answer: (a) Condoms ​​​

4.2) How physical barrier prevent pregnancy ? (a) They kill the sperms. (b) They kill the ovum. (c) They prevent intercourse. (d) They prevent fertilisation

Answer: (d) They prevent fertilisation. ​​​

4.3) How chemical methods prevent pregnancy ? (a) Vaginal pills contain chemical called spermicides which kill the sperms.  (b) Oral pills prevent ovulation so there will be no fertilisation. (c) Oral pills stop menstruation in females. (d) Both (a) and (b) 

Answer: (d) Both (a) and (b) ​​​

4.4) Select the correct statement regarding surgical method of birth control.  (a) It involves termination of pregnancies in women particularly after eight weeks of conception. (b) Small portion of sperm duct or vas deferences in males is removed by surgical operation and both cut ends are ligated properly. (c) Small portion of oviducts in females is removed by surgical operation and cut ends are ligated.  (d) Both (b) and (c) 

Answer: (d) Both (b) and (c) ​​​

4.5) Select the correct statement regarding birth control methods. (a) Barrier method of birth control also protects the couple from sexually transmitted diseases. (b) Some women experience unpleasant side effects on taking oral pills because of change in hormonal balance in body. (c) Surgical method in males is called vasectomy and in females is called tubectomy. (d) All of these

Answer: (d) All of these ​​​

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Case Study and Passage Based Questions for Class 10 Science Chapter 8 How Do Organisms Reproduce

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Case Study Questions for Class 10 Science Chapter 8 How Do Organisms Reproduce

In CBSE Class 10 Science Paper, Students will have to answer some questions based on  Assertion and Reason . There will be a few questions based on case studies and passage based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.

Here, we have provided case based/passage based questions for Class 10 Science  Chapter 8 How Do Organisms Reproduce

Case Study/Passage Based Questions

Question 1:

The male reproductive system consist of portions which produce the germ-cells and other portions that deliver the germ-cells to the site of fertilisation. Testes are located outside the abdominal cavity in scrotum because sperm formation requires a lower temperature than normal body temperature. It also has a role of secretion of male sex hormone which brings changes in appearance seen in boys at the time of puberty. Vas deferens unites with a tube coming from urinary bladder. Urethra is a common passage for sperms and urine. Prostate gland and seminal vesicles add their secretions so that sperms are now in fluid.

(i) Name the sex hormone associated with males. (a) Testosterone (b) Progesterone (c) Oestrogen (d) None of these

(ii) Which of the following statements is incorrect ? (a) Sperms are present in a fluid (b) Fluid provides nutrition to sperms (c) Fluid makes easier transportation of sperms (d) Fluid helps to bind the sperms together

(iii) Testes are located outside the abdominal cavity in scrotum because (a) sperms formation requires higher temperature than body temperature (b) sperms formation requires lower temperature than body temperature (c) it is easier to transport sperms from the scrotum (d) None of these

(iv) Which of the following statement is incorrect? (a) Sperms and urine has a common passage from urethra. (b) Sperms have long tail that helps them to move forward. (c) Sperms contain genetic material. (d) Sperms formation requires 1–3°C higher temperature than normal body temperature.

(v) What is the nature of semen? (a) slightly acidic (b) Neutral (c) Slightly basic (d) Strongly basic

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Case Study Chapter 8 How do the Organisms Reproduce

Please refer to Chapter 8 How do the Organisms Reproduce Case Study Questions with answers provided below. We have provided Case Study Questions for Class 10 Science for all chapters as per CBSE, NCERT and KVS examination guidelines. These case based questions are expected to come in your exams this year. Please practise these case study based Class 10 Science Questions and answers to get more marks in examinations.

Case Study Questions Chapter 8 How do the Organisms Reproduce

Case/Passage – 1

When the branches of a plant growing in the field are pulled towards the ground and a part of them is covered with moistsoil (leaving the tips of the branches exposed above the ground), then after sometime new roots develop from the parts of branches buried in the soil. On cutting these branches from the parent plant, new plants are produced from the cut parts of branches which had developed roots.

Question: Name any two plants which are grown for their flowers and propagated by this method.  

Jasmine and China rose

Question: What type of branches should a plant have to be able to be propagated by this method?  

Slender branches (Thin branches)

Question: What is this method of propagation of plants known as?    

Layering 

Question: Name one plant which gets propagated by this method naturally by forming runners (soft horizontal stems running above the ground)  

LStrawberry

Question: Name any two plants which are grown for their fruits and propagated by this method.  

Lemon and Guava

Case/Passage – 2

When an insect sits on the flower of a plant then some particles, present on the top of little stalks in the flower get stick to its body hair. When this insect now sits on the flower of another similar plant, then particles attached to the hair of insect are shifted to top of a flask-shaped organ at the centre of a flower. This particle grows a long tube B from the top of flask-shaped organ through which C moves down and reaches the bottom of the flask-shaped organ. Here C fuses with the nucleus of D, present in structure E. The fusion of C and D forms a new cell F which grows and develops into a seed of the plant. 

Question: What are these particles? Name the process by which these particles are transfered from one flower to other flower of another similar plant. 

These particles are known as pollen grains; cross pollination

Question: What is C which moves down through the tube B?    

  C is male gamete.pollen grains; cross pollination

Question: What is the name of tube B?      

  Pollen-tube 

Question: What is F?      

    F is fertilised egg (zygote).

Question: Name D and E.    

      D is female gamete (ovum or egg); E is ovule

Case/Passage – 3

The male reproductive system consists of portions which produce the germ-cells and other portions that deliver the germ-cells to the site of fertilisation. The formation of germ-cells or sperms takes place in the testes. These are located outside the abdominal cavity in scrotum because sperm formation requires a lower temperature than the normal body temperature. We have discussed the role of the testes in the secretion of the hormone, testosterone, in the previous chapter. In addition to regulating the formation of sperms, testosterone brings about changes in appearance seen in boys at the time of puberty. The sperms formed are delivered through the vas deferens which unites with a tube coming from the urinary bladder. The urethra thus forms a common passage for both the sperms and urine. Along the path of the vas deferens, glands like the prostate and the seminal vesicles add their secretions so that the sperms are now in a fluid which makes their transport easier and this fluid also provides nutrition. The sperms are tiny bodies that consist of mainly genetic material and a long tail that helps them to move towards the female germ-cell. 

Question: The seminiferous tubules of the testes are lined by the germinal epithelium consisting of (a) sertoli cells (b) cells of germinal epithelium (c) cells of Leydig or interstitial cells (d) secondary spermatocytes 

Question: The seminiferous tubules of the testes are lined by the germinal epithelium consisting of (a) spermatids (b) cells of Sertoli (c) spermatogonium (d) spermatocytes   

Question: In man, Cryptorchidism is the condition when  (a) testes do not descent into the scrotum (b) there are two testes in each scrotum (c) testis degenerates in the scrotum (d) testis enlarges in the scrotum   

Question: Another name for Bulbourethral gland is (a) Meibomian gland (b) Prostate gland (c) Perineal gland (d) Cowper’s gland    

Question: Which of these is an accessory reproductive gland in male mammals (a) Inguinal gland (b) Prostate gland (c) Mushroom-shaped gland (d) Gastric gland

Case/Passage – 4

The male reproductive system consist of portions which produce the germ-cells and other portions that deliver the germ-cells to the site of fertilisation. Testes are located outside the abdominal cavity in scrotum because sperm formation requires a lower temperature than normal body temperature. It also has a role of secretion of male sex hormone which brings changes in appearance seen in boys at the time of puberty. Vas deferens unites wih a tube coming from urinary bladder. Urethra is a common passage for sperms and urine. Prostate gland and seminal vesicles add their secretions so that sperms are now in fluid.

Question. Testes are located outside the abdominal cavity in scrotum because (a) sperms formation requires higher temperature than body temperature (b) sperms formation requires lower temperature than body temperature (c) it is easier to transport sperms from the scrotum (d) None of these

Question. Which of the following statement is incorrect? (a) Sperms and urine has a common passage from urethra. (b) Sperms have long tail that helps them to move forward. (c) Sperms contain genetic material. (d) Sperms formation requires 1–3°C higher temperature than normal body temperature.

Question. What is the nature of semen? (a) slightly acidic (b) Neutral (c) Slightly basic (d) Strongly basic

Question. Name the sex hormone associated with males. (a) Testosterone (b) Progesterone (c) Oestrogen (d) None of these

Question. Which of the following statements is incorrect ? (a) Sperms are present in a fluid (b) Fluid provides nutrition to sperms (c) Fluid makes easier transportation of sperms (d) Fluid helps to bind the sperms together

Case/Passage – 5

Study the table related to sex ratio of females/1000 males in different states and answer the questions that follow:

Question. Which test is responsible for female foeticide? (a) UV-Spectroscopy (b) Ultrasound (c) MRI (d) X-Ray

Question. Which state of India has lowest sex ratio in 2013-15? (a) Punjab (b) Odisha (c) Haryana (d) Delhi

Question. Which of the following state improves sex ratio in 2013-15 from 2012-14? (a) Delhi (b) Karnataka (c) Bihar (d) Kerala

Question. Name the state which has males to female ratio to maximum extent in 2013-15. (a) Haryana (b) Kerala (c) West Bengal (d) Uttar Pradesh

Question. What is major cause of less females than males in India? (a) Male Foeticide (b) Female Foeticide (c) Natural (d) None of these

Class 10 Science How Do The Organism… Exam Questions

Question. List four categories of contraceptive methods. State in brief two advantages of adopting such preventive methods. Answer  : Four categories of contraceptive methods are:  a. Barrier method (Condoms) b. Surgical method (Vasectomy in males and Tubectomy in females) c. Withdrawal method d. Calendar method e. Hormonal method f. IUCD/Copper-T/Loop (any four) Two advantages: a. Helps in maintaining health of women. b. Helps in preventing STDs especially AIDS. c. Helps in birth control.

Question. List any two modes of asexual reproduction. Under which mode of reproduction is vegetative propagation placed and why? List two advantages of vegetative propagation. Answer :  Two modes of asexual reproduction are fission Regeneration Vegetative propagation is placed under asexual reproduction as reproduction happens from any part of a plant. It may be either leaf, shoot or root. Advantages are: a. The plants bear flowers and fruits earlier than those propagated sexually. b. Plants have lost capacity to form seeds hence they are propagated vegetatively.

Question. Study the diagram given below:  (Image 94) a. Identify the process. b. Which organism uses the above method of reproduction? c. How is the above method different from the process of fragmentation?  or In context of reproduction of species, state the main difference between fission and fragmentation. Also give one example of each. Answer : a. Binary fission. b. Amoeba. c. Binary fission occurs in unicellular organisms only. In fragmentation the body of a simple multicellular organism breaks down into many ‘fragments’. All cells undergo division and the organism develops from each fragment.

Question. a. Identify the asexual method of reproduction in each of the following organisms: (i) Rose (ii) Yeast (iii) Planaria b. What is fragmentation? Name a multicellular organism which reproduces by this method. Answer :  a. (i) Vegetative propagation by stem. (ii) Budding (iii) Regeneration b. Fragmentation is a asexual method of reproduction in which an organism simply breaks up into smaller pieces/ fragments upon maturation. These pieces or fragments grow into new individuals. Spirogyra is the multicellular organism with relatively simple body organisation which reproduces through this simple method of reproduction, i.e., fragmentation.

Question. a. Give one example each of sexually transmitted diseases in each of following cases (i) Bacterial infections (ii) Viral infections b. How can spread of these diseases be prevented? or Name one sexually transmitted disease each caused due to bacterial infection and viral infection. How can they be prevented? Answer :  a. Bacterial infections: Syphilis, Gonorrhoea. Viral infections: Warts, AIDS, Hepatitis B, Herpes. b. Spread of these diseases can be prevented by using physical barrier, avoiding sex with multiple partners.

Question. DNA content has the tendency to double itself during sexual reproduction due to combining of the genetic materials from the two parents. How the problem of DNA doubling can be solved to maintain the  consistency of the genetic material throughout the species? or “The chromosome number of the sexually reproducing parents and their offsprings is the same”. Justify the statement. Answer :  DNA doubling is always followed by cell division. Due to this special cell division, gametes form with half the content of DNA and single set of chromosomes. These gamete fuse to form zygote on fertilization. Thus the characteristic number of chromosome and the normal DNA content for a cell is regained. Thus the consistency of the genetic material throughout the species is maintained and for the same reason the chromosome number of the sexually reproducing parents and their offsprings is the same.

Question. Explain the structure of the female reproductive system of humans. Answer :  Female Reproductive System consists of ovaries, fallopian tubes, uterus and vagina. a. Ovaries are located inside the abdominal cavity, near the kidney. It performs two functions: • Produce female germ – cells/eggs. Every month one egg is produced • Secrete hormones like Estrogens which stimulate the development of secondary sexual characteristics at puberty. b. Fallopian Tubes carry the egg from ovary to the womb; egg gets fertilized in the oviducts only if it meets a sperm. c. Uterus is a elastic bag like structure. The fertilized egg, the zygote gets implanted in the fining of uterus and develops into an embiyo. d. Vagina (Birth Canal) receives the sperms as well as child is borne through it.

Question. Give the functions of the following in the process of reproduction: a. Pollen tube. b. ovary, c. Stigma. Answer :  a. Pollen tube carries male gamete from stigma to ovule. b. Ovary has ovule and forms fruit to protect and dispersal of seeds c. Stigma receives pollen during pollination.

Question. Justify the following statements: a. Variation is beneficial for the species over a period of time. b. New offsprings produced are similar to their parents but not identical. c. Binary fission is different in Amoeba and Leishmania. Answer :  a. Variations help a population in the process of natural selection and accumulation of adaptations in a population. It leads to evolution of a species. b. Offspring, especially when produced sexually, have minor differences or variations among themselves hence they may not look identical. By virtue of them being from same species they look similar. c. Binary fission in Amoeba is in any plane but in Leishmania it is in a fixed plane.

Question. a. Give the functions of: (i) Stigma (ii) Ovary b. State in brief the formation of seed in a flower. Answer :  a. (i) The sticky terminal part of the carpel is called stigma. It receives pollen. (ii) The swollen bottom part of the carpel is called ovary. It contains female germ cells which form seed after fertilization. b. After fertilization, the zygote divides several times to form an embryo within the ovule. The ovule develops a tough coat and is gradually converted into a seed.

Question. In the diagram of human male reproductive system given below: 

a. Label parts A and B. b. Name the hormone produced by organ “X’. What is the role of this hormone in human male? c. Mention the name of substances that are transported by tubes (i) C and (ii) D. Answer :  a. A – seminal vesicle, B – prostate gland. b. Testosterone: It controls gamete formation/ secondary sex organs/ accessory glands. c. C – sperms, D – sperms/semen and urine.

Question. What happens when: a. APlanaria is cut into three different pieces, b. Leaf of the Bryophyllum with notches fall on the soil. c. Testosterone is released in the male reproductive system. Answer :  a. Three new Planaria will form due to regeneration. b. New plantlets will form from these buds helping the plant to propagate vegetatively. c. The male shows masculine features and attains fertility. Sperm starts forming in testis.

Question. What is vegetative propagation? List two advantages and two disadvantages of vegetative propagation. Answer :  Method of producing new plants from vegetative parts like roots, stem and leaves is called vegetative propagation. Advantages are: a. The plants bear flowers and fruits earlier than those propagated sexually. b. Plants have lost capacity to form seeds hence they are propagated vegetatively. Disadvantages are: a. Such plants are genetically similar to parent plants and are vulnerable to infections and diseases. b. They do not have variations therefore do not adapt well to changing environment, the plant species does not evolve.

Question. List three techniques to prevent pregnancy. Which of them is not meant for males? How does the use of such techniques have an impact on health and prosperity of a family? or List any four methods of contraception used by humans. How does their use have a direct effect on the health and prosperity of a family? Answer :  Three techniques to prevent pregnancy: a. Mechanical barrier — male or female. b. Taking oral pills/i-pill/saheli – changing the hormonal balance of the body so that eggs are not released. c. Use of the loop or the Copper-T. d. Surgical method – tubectomy / vasectomy Use of hormonal preparations is not meant for males. Effect on Health and Prosperity: a. Health of women is maintained b. Parents can give more attention to children c. More resources can be made available.

Question. What is the effect of DNA copying, which is not perfectly ccurate, on the reproduction process? How does the amount of DNA remain constant though each new generation is a combination of DNA copies of two individuals? Answer :  a. DNA copying leads to more variations in the offspring. b. Sexually reproducing organisms have special lineage of cells which have only half the number of chromosomes as the parent cell. c. When such germ cells fused, a new individual is formed with the same amount of DNA as that of parent.

Question. Differentiate between the following: a. Placenta and uterus b. Unisexual and bisexual flowers c. Fertilization and germination Answer :  a. Placenta and uterus : The embryo gets nutrition from the mother’s blood with the help of a special tissue called placenta. After fertilization, embryo gets attached to the walls of uterus. b. Unisexual flowers contain either stamens or carpels. Bisexual flowers contain both stamens and carpels. c. Fertilization and germination : The fusion of male gamete with female gamete leading to the formation of zygote is known as fertilization. The growth of embryo (present in the seed) into seedling under appropriate conditions is known as germination.

Question. A part of the male reproductive system is shown below. Study the diagram and answer the questions that follow. 

a. Two part have been incorrectly labelled. Identify them. b. Give the function of urethra. c. Which hormone is released by testis? Answer : a. Testis, penis. b. Urethra serves as a common passage for both sperms and urine. c. Testosterone.

Question. List six specific characteristics of sexual reproduction. Answer : C haracteristics of sexual reproduction: a. Two parents are involved. b. Two dissimilar gametes are formed by meiosis. c. Variations are produced. d. Occurs in all the higher and some of the lower organisms. e. Fertilization / fusion of gametes leading to zygote formation.

Question. List four points of significance of reproductive health in a society. Name any two areas related to reproductive health which have improved over the past 50 years in our country. Answer :  Significance: a. Prevent STDs. b. Advantage of small family. c. Less mortality among new-borns. d. Reduces the cases of maternal mortality. Areas which have improved: a. Family Planning. b. Decrease in STD cases.

Question. Mention one function each of the following parts with respect to the female reproductive system: a. Vagina b. Ovary Answer :   a. The uterus open into vagina through the cervix. The sperms enter through the vaginal passage during sexual intercourse. b. One egg (female gamete) is produced every month by one of the ovaries.

Question. List and explain in brief three methods of contraception. or List any four methods of contraception. How are they helpful to young couples? Answer :  Four methods of contraception: a. Condoms b. Copper-T c. Diaphragm d. Oral pills  All these help in family planning as it helps in keeping gap between two children. They help in proper utilization of family resources.

Question. Write scientific name for malarial parasite. How is fission in amoeba different from that of malarial parasite? Answer :  a. Plasmodium, b. Fission in amoeba produces two daughter cells – binary fission. Fission in Plasmodium produce many daughter cells – multiple fission,

Question. a. Give the functions of the following: 1. Pollen tube 2. Ovary b. List any two changes observed in the body of a female during puberty. Answer : a. (i) Transfer of male gamete. (ii) Production of female gamete. b. (i) Growth of mammary glands. (ii) Onset of menstrual cycle.

Question. What is meant by DNA copying? Mention its importance in reproduction. Answer :  Cells use chemical reactions to build copies of their DNA. This creates two copies of the DNA in a reproducing cell. DNA copying is accompanied by the creation of an additional cellular apparatus to facilitate the DNA copies to separate with its own cellular apparatus. DNA copying gives rise to some inbuilt tendency for variation during reproduction which is the basis for evolution.

Question. a. What are sexually transmitted diseases? Name any one which is caused by bacteria and one caused by viral infection. b. Mention any two methods to avoid such diseases. Answer :  a. Diseases that spread through the sexual contact are called sexually transmitted diseases. (i) Gonorrhoea or syphilis is caused by bacteria. (ii) Warts, HTV, AIDS is caused by virus. b. (i) Use of condoms on penis.

(ii) Use covering on vagina.

Question. a. How do organisms reproduced by fission? b. Write names of any two organisms which reproduce by this method. c. Differentiate between the fission of Leishmania and Plasmodium. Answer :  a. Cell division takes place which leads to creation of new individuals. b. Bacteria, Protozoa. c. Leishmania — binary fission occurs in a definite orientation. Plasmodium — undergoes multiple fission,

Question. Give reasons: a. Wind acts as a pollinating agent. b. Variation is essential and beneficial to a species. c. Use of condoms prevents pregnancy. Answer :  a. Transfer of pollen grains from anther to stigma. b. Helps in evolution and survival. c. Prevents fertilization – Barrier method.

Question. What are secondary sexual characters in humans? Name one such character of male and female. Answer :  The characters which distinguish a male from female are called secondary sexual characters. Secondary sexual characters of male are moustache, beard, thick growth of hair on body, strong muscles and harsh voice. Secondary sexual characters of female are less hair on body, broad hips, development of breasts and soft voice.

Question. Name and explain the method by which Rhizopus reproduces. Answer :  Rhizopus reproduces by spore formation. Method: It is a method of asexual reproduction. 

Spores are produced in a structure called sporangium.

Long Answer Questions

Question. Name the type of asexual reproduction demonstrated by the following organisms: a. Amoeba b. Rhizopus c. Planaria d. Plasmodium e. Bryophyllum Answer :  a. Binary fission b. Spore formation c. Fragmentation d. Multiple fission e. Vegetative propagation

Question. Answer the following: a. How is zygote formed? b. State the function of placenta in the mother’s body. c. At what interval the egg is formed in human female ovary? d. Name two STDs caused by bacterial infection. e. Why is prenatal sex determination prohibited? Answer :  a. Zygote is formed by the fusion of male and female gamete. b. Placenta is a special tissue through which the developing embryo/foetus gets nutrition from mother’s blood. It also transports wastes of the embryo into mother’s blood. c. Ovulation releases mature ovum from ‘ the ovary. It happens once during a menstrual cycle that is for roughly 28 days. d. STDs caused by bacterial infection are Gonorrhoea and Syphilis. e. Prenatal sex determination is misused and it may be the reason for female foeticide.

Question. How does vegetative propagation occur in nature? Explain with four different examples. Answer :  There are many plants in which parts like the root, stem and leaves develop into new plants under appropriate conditions. This is called as vegetative propagation. Examples of vegetative propagation: a. Adventitious buds: In Bryophyllum, adventitious buds grow in the notches along the leaf margin, which when fall on the soil, develop into new plants. b. Cutting: A piece of stem, root, leaf or even a bulb scale is placed partly under moist soil which grows into a new plant, e.g., rose. c. Layering: A part of the stem is pulled out and buried in the soil. The layered stem grows into a new plant, e.g., Pudina. d. Grafting: In grafting, two parts from two different plants are joined together so that they can unite and grow into a new plant, e.g., sugarcane.

Question. a. (i) Write full form of DNA. (ii) State the role of DNA in the cell nucleus, (iii) What will be the after effect if the information of the DNA is changed. b. Explain the importance of DNA copying in reproduction. Answer :  a. (i) Deoxyribo Nucleic Acid. (ii) Informational source for making proteins. (iii) Proteins will be changed. b. Its only due to DNA copying that body designs are similar because DNA cell nucleus carries information for making proteins if DNA copying will not take place then body design will change.

Question. a. Identify A,B,C and D in the given diagram and write their names. 

b. What is pollination? Explain its significance.  c. Explain the process of fertilization in flowers. Name the parts of flower that develop after fertilization into (i) seed (ii) fruit Answer :  a. A – pollen grain; B – stigma; C – Pollen tube, D – Female germ cell/Egg cell. b. Pollination – Transfer of pollen grains from anther to the stigma of a flower. Significance of pollination – Process of pollination leads to fertilization as it brings the male and female gametes together for fusion. c. After a pollen falls on a suitable stigma, the pollen tube grows out of the pollen grain and travels through the style to reach the ovule in the ovary. Here the male germ cell (carried by the pollen tube) fuses with the female germ cell to form a zygote.

Question. Define the following processes: a. Fertilization b. Menstruation c. Binary fission d. Vegetative propagation e. Regeneration Answer : a. The fusion of male gamete with female gamete is known as fertilization. b. Menstruation cycle takes place every month when egg is not fertilized. It lasts for about two to eight days and during this cycle the lining of uterus slowly breaks and comes out through the vagina as blood and mucus. c. Binary fission is the splitting of nucleus into two daughter cells which can take place in any plane. It can be observed in Amoeba. d. When vegetative part of a plant like the root, stem or leaves develops into new plant under appropriate conditions, it is known as vegetative propagation. e. When body of an organism cuts into any number of pieces and each piece grows into a complete organism. This is known as regeneration. Hydra and Planaria reproduce through this process.

Question. a. Write the function of following parts in human female reproductive system: (i) Ovary (ii) Oviduct (iii) Uterus b. Describe in brief the structure and function of placenta. or Write the functions of the following in human female reproductive system: Ovary, oviduct, uterus How does the embryo get nourishment inside the mother’s body? Explain in brief. Answer :  a. Functions of Ovary, oviduct, uterus Functions of Ovary (i) Production of female hormone, oestrogen and progesterone. (ii) Production of female gamete / egg /germ cell. Functions of Oviduct: (i) Transfer of female gamete from the ovary. (ii) Site of fertilization. Functions of Uterus: (i) Implantation of Zygote/ embryo. (ii) Nourishment of developing embryo. b. Placenta is a special disc like tissue embedded in the mother’s uterine wall and connected to the foetus / embryo. Placenta provides a large surface area for glucose and oxygen/nutrients to pass from the mother’s blood to the embryo/ foetus.

Question. Differentiate between: a. Pollen tube and Style b. Fission of Amoeba and Plasmodium c. Fragmentation and regeneration d. Bud of Hydra and bud of Bryophyllum e. Vegetative propagation and spore formation. Answer :   a. Pollen tube forms and male gametes are carried by it to the ovule. Style is part of female part- carpel through which pollen tube passes. b. Amoeba shows binary fission where one cell splits into two equal halves. Plasmodium (malarial parasite) shows multiple fission where one cell divides into many daughter cells simultaneously. c. Fragmentation occurs in multi-cellular organisms with simple body organisation like Spirogyra (a filamentous alga). It involves breaking up of a filament into many fragments and each fragment growing into new individual. Regeneration is the ability to give rise to new individuals from the body parts of the parent individual, e.g., Hydra and Planaria, if their bodies get broken into many pieces, each piece is capable of regrowing into a complete individual. d. In Hydra, a bud is formed at a specific site by repeated cell division and develops into a tiny hydra. In Bryophyllum, vegetative buds arise from the notches of its leaves and develops into a new plantlet. e. Vegetative Propagation is the development of new plants from parts like root, leaf and stem under suitable conditions, e.g., Bryophyllum vegetative buds arise from the notches of its leaves. In potato, ginger, garlic etc. it occurs through stems. Spore formation: A spore is a special cell protected by thick coating. It is capable of germinating into a new plant when comes in contact with suitable and environment conditions and moist surface, e.g., in Rhizopus (bread mould), they are formed inside reproductive, bob¬like sacs called sporangia.

Question. What happens when a. Testosterone is released in the male reproductive system. b. Pollen grain falls on the stigma of flower. c. Egg fuses with the sperm cell. d. A Planaria is cut into three different pieces. e. Buds are formed on the notches of leaf of the Bryophyllum. Answer :  a. The male shows masculine features and attains fertility/ sperm starts forming in testis. b. Pollen tube forms and male gametes are carried by it to the ovule. c. Fertilization occurs and a zygote forms. d. Three new Planaria will form due to regeneration. e. New plantlets will form from these buds helping the plant to propagate vegetatively.

Question. Explain what happens when: a. Testosterone is released in males. b. Pollen grain falls on the stigma of the flower. c. Egg fuses with sperm cell. d. Planaria is cut into many pieces. e. Buds are formed on the notches of the Bryophyllum leaf. Answer :  a. (i) Formation of sperms, change in appearance. (ii) Thick hair growth on the face and voice begin to crack. b. A tube grows out of the pollen grain and travel through the style to reach the ovary. c. Zygote is formed (fertilization). d. Each piece grows into a complete organism. e. Buds may fall on the soil and develop into new plants.

Question. a. Identify the organisms A, B and the mode of asexual reproduction exhibited by them. 

b. How will an organism be benefitted if it reproduces through spores? c. Mention the two asexual methods by which hydra can reproduce. Explain briefly any one such method. Answer :  a. (i) Bryophyllum – vegetative propagation. (ii) Plasmodium – multiple fission. b. Spores are covered with thick walls that protect them until they come into contact with a moist surface. c. Budding and Regeneration. Budding : A bud develops as an outgrowth due to repeated cell division at a specific site, these buds develop into tiny individuals, mature and detach from the parent to become new individuals. Regeneration: Specialized cells divide to form large number of cells and undergo changes to become various cell types and tissues.

Question. a. Identify the organisms in figure A, B, C and D.      

b. Identify the life process commonly shown in all the figures, c. How is this life process .advantageous to the organisms? Mention any two advantages. Answer : a. (A) Hydra (B) Rhizopus (C) Bryophyllum (D) Planaria b. Asexual mode of reproduction c. (i) Only one individual is required. (ii) Progeny is identical like parents (iii) Produced in large number (Any two)

Question. a. Draw a diagram of the longitudinal section of a flower and label on it sepals, petal, ovary and stigma. b. Write the names of male and female parts of a flower. Answer :  

b. Male Part : Stamen; Female Part : Carpel/pistil

Question. a. List two reasons for the appearance of variations among the progeny formed by sexual reproduction.

b. (i) Name the part marked A in the diagram. (ii) How does “A” reaches part B? (iii) State the importance of , the part C. (iv) What happens to the part marked D after fertilization is over? Answer :  a. Sexual reproduction confers new characteristics on the offspring due to genetic recombination occurring during gamete formation in the sex organs. Moreover it involves union of two gametes coming from two parents which different genetic combination. Thus it ensures more diversity in characteristics. b. (i) Pollen (ii) Pollination (iii) Pollen tube carries male gametes to the ovule in ovary. (iv) Ovule turns into seeds.

Question. Identify the following methods and giving one example of each: a. Process in which reproduction takes place by breaking up of parent into fragments. b. Process of dividing of organisms into many cells simultaneously. c. Process of reproduction by formation of bud on parent body. d. Process of reproduction by formation of spores. e. Process used by multicellular organisms to reproduce by cutting into many pieces each piece forms a new individual. Answer :  a. Fragmentation, Spirogyra b. Multiple fission, Plasmodium c. Budding, Hydra d. Spore formation, Rhizopus e. Regeneration, Planaria.

Question. a. Draw a sectional view of human female reproductive system and label the part where: (i) Eggs develop (ii) Fertilization takes place (iii) Fertilized eggs get implanted. b. Describe in brief, the changes the uterus undergoes: (i) To receive the zygote (ii) If zygote is not formed. Answer :  a.

(i) Ovary (ii) Oviduct or fallopian tube (iii) Uterus or uterus wall b. (i) It becomes thicker due to development of blood vessels and glands in it. (ii) It gets peeled and shed off along with mucus, blood, dead ovum during menstruation

Question. List five distinguishing features between sexual and asexual types of reproductions in tabular form. Answer :  

Question. a. Name the human male reproductive organ that produces sperms and also secretes a hormone. Write the functions of the secreted hormone. b. Name the parts of the human female reproductive system where (i) Fertilization takes place, (ii) Implantation of the fertilized egg occurs.  Explain how the embryo gets nourishment inside the mother’s body. Answer : a Testis – secrete male hormone – testosterone. Functions : (i) Formation of sperms, (ii) Development of secondary sexual characters. b. (i) fallopian tube/oviduct. (ii) uterus.

Placenta is a special disc like tissue embedded in the mother’s uterine wall and connected to the foetus/embryo. Placenta provides a large surface area for glucose and oxygen/ nutrients to pass from the mother’s blood to the embryo/ foetus.

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Case Study - 1

The sexual act always has the potential to lead to pregnancy. Pregnancy will make major demands on the body and the mind of the woman, and if she is not ready for it, her health will be adversely affected. Therefore, many ways have been devised to avoid pregnancy.

Q1: What are the different methods to prevent pregnancy? Ans: Uses of contraceptive such as condoms, pills, copper -T and surgical methods. Q2: What are the surgical methods to prevent pregnancy? Ans: Tubectomy in females and vasecotomy in males. Q3: Why the female sex ratio is declining day by day? Ans: Due to female foeticides by doing illegal sex selective abortion of female foetuses. Q4: Which contraceptive methods have large side effects? Ans:  Oral pills and by changing the hormonal balance leads to high side effect. Q5: Why should one have the knowledge about sexual act and the disease causing by it? Ans:  To stay healthy and free free from sexually transmitted disease one should be aware of the disease cause by bacteria and viruses such as gonorrhoea, syphilis and HIV- AIDS.

Case Study - 2

Chromosomes in the nucleus of a cell contain information for inheritance of features from parents to next generation in the form of DNA (Deoxyribo Nucleic Acid) molecules. The DNA in the cell nucleus is the information source for making proteins. If the information is changed, different proteins will be made. Different proteins will eventually lead to altered body designs. Therefore, a basic event in reproduction is the creation of a DNA copy. Cells use chemical reactions to build copies of their DNA.

Q1: What is the importance of variation? Ans: Variation is important for the survival of species over time. Variation make the species resistant to the changing environment and hence, it make easy for their survival. Q2: Which mode of reproduction does not show much variation? Ans:  Generally, asexual reproduction show less variation which includes budding, fragmentation, fission etc. Q3: What are the different modes of reproduction of single celled organism? Ans: Fission, fragmentation, Budding  and regeneration. Q4: What are the features of sexual reproduction? Ans:  It includes both the parents to produce offsprings and DNA copy is a crucial part of it. Q5: Which mode of reproduction is better and why? Ans:  Sexual reproduction is better than asexual reproduction as the chances of survival of the species is higher in sexual reproduction.

Case Study - 3

There are many plants in which parts like the root, stem and leaves develop into new plants under appropriate conditions. Unlike in most animals, plants can indeed use such a mode for reproduction. This property of vegetative propagation is used in methods such as layering or grafting to grow many plants like sugarcane, roses, or grapes for agricultural purposes

Q1: What are the advantages of vegetative propagation? Ans:  All plants that are produced by such method are genetically similar to their parent and have all its characteristics. easy, less expensive and a fast method. Q2: Give a example of vegetative propagation through buds? Ans: Bryophyllum Q3: What is tissue culture? Ans: New plants are grown first in suitable artificial medium and then placing it in the soil to grow into mature plants. Q4: What is grafting? Ans: New plants are grown by joining a scion(upper portion of plant) to a stock of other plants in such a manner that they get united to each other. Example: Roses Q5: What are the examples of layering? Ans:  Jasmine or Grapevine.

Case Study - 4

The reproductive parts of angiosperms are located in the flower. You have already studied the different parts of a flower – sepals, petals, stamens and pistil. Stamens and pistil are the reproductive parts of a flower which contain the germ-cells.The flower may be unisexual (papaya, watermelon) when it contains either stamens or pistil or bisexual (Hibiscus, mustard) when it contains both stamens and pistil.

Q1: What is the male reproductive parts of flower? Ans:  Stamen is the male reproductive part of flower and it consist of anther and filament. Q2: What are the different part of pistil? Ans:  Stigma, style and ovary. Q3: What is pollination? Ans: The transfer of pollen grains from the stamen to the stigma of flower is called pollination. Q4: Where does fertilization occur in flower? Ans: The fertilization takes place inside the ovule. Q5: What are the two types of pollination? Ans:  Self pollination and cross pollination.

Case Study - 5

When a girl is born, the ovaries already contain thousands of immature eggs. On reaching puberty, some of these start maturing. One egg is produced every month by one of the ovaries. The egg is carried from the ovary to the womb through a thin oviduct or fallopian tube. The two oviducts unite into an elastic bag-like structure known as the uterus. The uterus opens into the vagina through the cervix.

Q1: What is fertilization? Ans:  The fusion of male gametes(sperms) and the female gametes(egg) to form zygote is called fertilization. Q2: Where does fertilization occur? Ans: Fertilization occur in the oviduct or Fallopian tube. Q3: What is placenta? Ans: It is an special tissue which provide nutrition from mother’s blood to developing embryo. Q4: What are the different parts of female reproductive system? Ans: Fallopian tube, ovary, uterus, vagina and cervix. Q5: What happens when egg is not fertilized? Ans: If the egg is not fertilized, the thick lining of uterus is not needed. So, it breaks slowly and comes out through vagina as blood and vagina, which is called as menstruation.

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How Do Organisms Reproduce Case Study Based Questions Class 10

Students who are studying in CBSE class 10 board, need to get the knowledge about the How Do Organisms Reproduce Case Study Based Questions. Case based questions are generally based on the seen passages from the chapter How Do Organisms Reproduce. Through solving the case based questions, students can understand each and every concept. 

 With the help of How Do Organisms Reproduce Case Study Based Questions, students don’t need to memorise each answer. As answers for these case studies are already available in the given passage. Questions are asked through MCQs so student’s won’t take time to mark the answers. These multiple choice questions can help students to score the weightage of How Do Organisms Reproduce. 

How Do Organisms Reproduce Case Study Based Questions with Solutions 

Selfstudys provides case studies for the Class 10 Science chapter How Do Organisms Reproduce with solutions. The Solutions can be helpful for students to refer to if there is a doubt in any of the case studies problems. The solutions from the Selfstudys website are easily accessible and free of cost to download. This accessibility can help students to download case studies from anywhere with the help of the Internet. 

How Do Organisms Reproduce Case Study Based Questions with solutions are in the form of PDF. Portable Document Format (PDF) can be downloaded through any of the devices: smart phone, laptop. Through this accessibility, students don't need to carry those case based questions everywhere. 

Features of How Do Organisms Reproduce Case Study Based Questions

Before solving questions, students should understand the basic details of How Do Organisms Reproduce. Here are the features of case based questions on How Do Organisms Reproduce are:

• These case based questions start with short or long passages. In these passages some concepts included in the chapter can be explained.
• After reading the passage, students need to answer the given questions. These questions are asked in the Multiple Choice Questions (MCQ). 
• These case based questions are a type of open book test. These case based questions can help students to score well in the particular subject. 
•  These How Do Organisms Reproduce Case Study Based Questions can also be asked in the form of CBSE Assertion and Reason .

Benefits of Solving How Do Organisms Reproduce Case Study Based Questions

According to the CBSE board, some part of the questions are asked in the board exam question papers according to the case studies. As some benefits of solving How Do Organisms Reproduce Case Study Based Questions can be obtained by the students. Those benefits are: 

• Through solving case studies students will be able to understand every concept included in the chapter How Do Organisms Reproduce
• Passages included in the case study are seen passages, so students don’t need to struggle for getting answers. As these questions and answers can be discussed by their concerned teacher. 
• Through these students can develop their observation skills. This skill can help students to study further concepts clearly. 
• Case studies covers all the concepts which are included in the How Do Organisms Reproduce

How to Download How Do Organisms Reproduce Case Based Questions? 

Students studying in CBSE class 10 board, need to solve questions based on case study. It is necessary for students to know the basic idea of How Do Organisms Reproduce Case Study Based Questions. Students can obtain the basic idea of case based questions through Selfstudys website. Easy steps to download it are:

• Open Selfstudys website. 

• Bring the arrow towards CBSE which is visible in the navigation bar. 

• A pop-up menu will appear, Select case study from the list. 

• New page will appear, select 10 from the list of classes. 

• Select Science from the subject list. 

• And in the new page, you can access the How Do Organisms Reproduce Case Study Based Questions. 

Tips to solve How Do Organisms Reproduce Case Study Questions-

Students should follow some basic tips to solve How Do Organisms Reproduce Case Study Based Questions. These tips can help students to score good marks in CBSE Class 10 Science. 

• Generally, the case based questions are in the form of Multiple Choice Questions (MCQs). 
• Students should start solving the case based questions through reading the given passage. 
• Identify the questions and give the answers according to the case given. 
• Read the passage again, so that you can easily answer the complex questions. 
• Answer according to the options given below the questions provided in the How Do Organisms Reproduce Case Study Based Questions. 

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CBSE Class 10 Biology How Do Organisms Reproduce Important Questions and Answers for 2023

Cbse class 10 biology how do organisms reproduce important questions and answers: a ll important questions from the chapter how do organisms reproduce in cbse class 10 science. the questions are of all varieties: multiple choice questions, assertion reason questions, case study questions, and all descriptive questions such as very short answer questions, short answer questions and long answer questions..

CBSE Class 10 Biology How Do Organisms Reproduce Important Questions: In this article, we will cover all important questions from the chapter How do Organisms Reproduce in CBSE Class 10 Science. The questions are of all varieties: Multiple choice questions, Assertion Reason questions, Case Study questions, and all descriptive questions such as Very Short answer Questions, Short answer questions and Long answer questions. The answers to these questions are also provided here. These important questions and answers prepared by the subject experts are provided here for candidates of CBSE Class 10 Science board exam 2022-23 to help them prepare effectively. By practising these questions along with the sample paper questions and textbook exercises, students will be able to master the topics in the chapter. 

How Do Organisms Reproduce is the third chapter in the second unit World of Living. Earlier it was the eighth chapter in the syllabus. Since the syllabus was updated during the pandemic years, it is now Chapter 7. 

Chapter 7 How do Organisms Reproduce covers the following topics:  Reproduction in animals and plants (asexual and sexual) reproductive health - need and methods of family planning. Safe sex vs HIV/AIDS. Child bearing and women’s health.

CBSE Class 10 Biology How Do Organisms Reproduce Important Questions

Multiple choice questions:.

Q.1. The two oviducts in a human female unite into an elastic bag like is known as

a. Vagina b. Uterus c. Fallopian tube d. Cervix

2. Where does fertilisation occur in human females?

a. Uterus b. Cervix c. Oviduct d. None of these

• Vegetative propagation 
• Contraception
• Increasing fertility 
• Avoiding miscarriage

4. Which is the portion on which grafting is done it provides the roots?

a. Stock b. Scion c. Both a and b d. None of these

5. When an animal is cut into pieces and each piece grows into a complex organism. What is the process?

a. Budding b. Fragmentation c. Spore formation d. Regeneration

6. Which among the following does not reproduce by spore formation:

(a) Penicillium fungus (b) Yeast fungus (c) Mucor fungus (d) Rhizopus fungus

7. What is the puberty age in human males?

a. 8-10 b. 10-12 c. 12-14 d. 14-16

8. Reason for the greater similarities among the off springs produced by asexual reproduction, is:

(i) Asexual reproduction involves only one parent

(ii) Asexual reproduction involves two parents

(iii) Asexual reproduction involves gametes

(iv) Asexual reproduction does not involve gametes

(a) (i) and (ii) 

(b) (i) and (iii)

(c) (ii) and (iv) 

(d) (i) and (iv)

9. Fruits are formed from

a. Stamen b. Stigma c. Ovary d. Ovule

10. An organism capable of reproducing by two asexual reproduction methods one similar to the reproduction in yeast and the other similar to the reproduction in Planaria is:

ASSERTION REASON QUESTIONS:

DIRECTION: Each of these questions contains an Assertion followed by Reason. Read them carefully and answer the question on the basis of following options. You have to select the one that best describes the two statements.

(a)Both A and R are true and R is the correct explanation of A.

(b)Both A and R are true but R is not the correct explanation of A.

(c)A is true but R is false.

• Assertion: Unisexual flowers have separate male and female Organs.
• Assertion: Condom is a safe contraceptive method to prevent pregnancy
• Assertion: Testes lie outside the body.
• Assertion: Spores are unicellular bodies.
• Assertion: Ovary is not an organ in the female reproductive system. 
• Assertion: Surgical methods are most effective methods of contraception.
• Assertion: Fertilisation will not occur in the absence of pollination.
• Assertion(A) : Asexual reproduction is a primitive type of reproduction.
• Assertion: Sexual reproduction involves two parents of different sexes, a male and a female
• Assertion: In internal fertilization male and female gametes fuse inside the female body
• Assertion: The size of human population is a cause for concern for many people .
• Assertion: Urethra in human male acts as urino-genital canal.
• Assertion(A) : The offspring produced by sexual reproduction is likely to adjust better in environmental fluctuation.
• Assertion : Ovary lies at the lower part of the stamen.
• Assertion: Warts is a sexually transmitted disease.

CASE STUDY BASED QUESTIONS:

1 Germination starts with the rapid intake of water by the seed through its micropyle. The first visible indication of germination is the swelling of the seed with a resultant increase in weight. It is also accompanied by the softening of the seed coat. Absorption of water causes a number of physiological changes in the seed. Germinating seeds exhibit increased respiratory activity. The embryo produces enzymes which convert the food materials stored in the cotyledons into soluble form usable by the growing embryo. Once the food is made available, cell division activity starts in the growing embryo. The growth of the embryonic tissue ruptures the seed coat.

(i) Which of the following is not connected with the germination of seed.

(a) It swells

(b) The seed coat softened

(c) It exhibits photosynthesis

(d) It exhibits respiration

(ii) Which among the following are true

(i) Radicle develops into root

(ii) Radicle develops into shoot

(iii) Plumule develops into root

(iii) Plumule develops into shoot

(c) (i) and (iv) 

(d) (ii) and (iv)

(iii) Which of the following is a part of seed.

(b) Radicle

(c) Plumule

(d) All of the above

(iv) The condition needed for the germination of the seed

(a) Moisture

(b) Temperature

(c) Both (A)and (b)

(d) None of the above

2 The growing size of the human population is a cause of concern for all people. The rate of birth and death in a given population will determine its size. Reproduction is the process by which organisms increase their population. The process of sexual maturation for reproduction is gradual and takes place while general body growth is still going on. Some degree of sexual maturation does not n ecessarily mean that the mind or body is ready for sexual acts or for having and bringing up children. Various contraceptive devices are being used by human beings to control the size of population.

1) What should be maintained for healthy society?

a) Rate of birth and death rate

b) Male and female sex ratio

c) Child sex ratio

d) None of these

2) Which contraceptive method changes the hormonal balance of the body?

b) Diaphragms

c) Oral pills

d) Both a) and b)

3) Common sign of sexual maturation in girls is

a) Low pitch voice

b) Appearance of moustache and beard

c) Development of mammary glands

d) Broadening of shoulders

4) What are common signs of sexual maturation in boys?

a) Broadening of shoulders

b) Development of mammary glands

c) Broadening of waist

DESCRIPTIVE QUESTIONS:

1) Newly formed DNA copies may not be identical at times. Give one reason.

2) Where is the zygote located in the flower after fertilization?

3) How does Plasmodium reproduce? Is this method sexual or asexual?

4) Name the part of Bryophyllum where the buds are produced for vegetative propagation.

5) Name the method by which Spirogyra reproduces under favourable conditions. Is this method sexual or asexual?

6) Name the causative agent of the disease “kala- azar” and its mode of asexual reproduction

7) In a bisexual flower in spite of the young stamens removed artificially, the flower produces fruit. Provide a suitable explanation for the above situation.

8) Define vegetative propagation.

9) Name two sex hormones.

10) What are the agents of pollination?

11) Define the terms unisexual and bisexual giving one example of each.

12) What are the limitations of the asexual mode of reproduction? Differentiate between asexual reproduction and sexual reproduction.

13) Explain how human embryo get nourished in mother body?

14) How do Plasmodium and Leishmania reproduce? Write one difference in their mode of reproduction.

15) Name the female reproductive part of a flower. Which part of a flower develops into a seed and a fruit? Where are the male germ cell and female gamete present in the flower?

16.) Name the male and female gametes in animals. What is fertilisation and where does it take place in human females?

17) Name an organism which reproduces by spore formation. List three conditions favourable for spores to germinate and grow.

18) What is the importance of variation in the survival of individuals?

19) Name and explain any three methods of contraception?

20) List the advantages of vegetative propagation

21) Explain various steps of budding in yeast.

22) Draw a human male reproductive system of a human and label the parts. Mention the function of vas deferens and ureter?

23) Define reproduction. How does it help in providing stability to the population of species?

• a) We can develop new plants from the leaves of Bryophyllum. Comment.
• b) List two advantages of vegetative propagation over other modes of reproduction.

25) Draw a diagram showing germination of pollen on the stigma of a flower. 

26) Draw a human female reproductive system of a human and label the parts.

By going through the important topics of Chapter 7 How Do Organisms Reproduce students will get a good idea of the topics from where the questions are expected and the types of questions to be asked in the CBSE Class 10 Science board exam paper. 

To get the CBSE Class 10 Science Sample Question Paper and Marking Scheme, click below:

 CBSE Class 10 Science Sample Question Paper and Marking Scheme

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Chapter 8 -How do Organisms Reproduce?

Important Questions for Class 10 Science Chapter 8 How Do Organisms Reproduce is provided here for students to help them prepare effectively for the board exam. By practising these questions, students will have a good revision. They will go through the important topics of Chapter 8 How Do Organisms Reproduce. Also, they get a good idea of the topics from where the questions are expected to be asked in the Science paper. Practising them will help in increasing the scores of students in Science subject.

Important Questions for Class 10 Science Chapter 8 How Do Organisms Reproduce- Download Free PDF

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Case Study Questions Class 10 Science How do Organisms Reproduce

Case study questions class 10 science chapter 8 how do organisms reproduce, cbse case study questions class 10 science how do organisms reproduce, case study : 1, case study : 2, case study : 3, case study: 4.

Ans: Sexual reproduction is better than asexual reproduction as the chances of survival of the species is higher in sexual reproduction.

CASE STUDY : 5

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Question 2 - Case Based Questions (MCQ) - Chapter 8 Class 10 - How do Organisms Reproduce?

Last updated at April 16, 2024 by Teachoo

Study the process depicted in the picture given below and answer any four question from (a) to (e):

(a) Which of these organisms divides by the above process?

(ii) spirogyra, (iii) leishmania, (b) how the above process is different from multiple fission., (c) which of the following statement is correct about the above type of reproduction, (i) it involves two individuals., (ii) it involves a mature parent cell., (iii) it involves union of two types of gametes..

• (iv) All of these

(d) Differentiate between fission in above organism and Leishmania.

(e) which of these are the characteristics of vegetative reproduction, i. involves two individuals, ii. daughter cells are genetically identical to the parent., iii. the cell division is only mitotic., (i) i and ii only, (ii) i, and iii only, (iii) ii and iii only.

The process depicted in the above image is binary fission.

Checking the options:

• (i) Amoeba - Reproduces through binary fission.
• (ii) Spirogyra - Reproduces through fragmentation. 
• (iii) Leishmania - Reproduces through binary fission.
• (iv) Yeast - Reproduces through budding.

Even though Amoeba and Leishmania reproduce through binary fission, Leishmania undergoes binary fission along a definite plane with respect to its flagellum whereas Amoeba undergoes binary fission along any plane.

In the process depicted above, binary fission does not occur along a definite plane. 

So, the correct answer is (i) Amoeba.

In binary fission, the parent organism splits into 2 daughter cells whereas in multiple fission, the parent organism splits into many daughter cells simultaneously.

Binary fission is an asexual mode of reproduction in which a single mature parent cell splits into 2 daughter cells.

Checking the options

• (i) It involves two individuals - This is incorrect.
• (ii) It involves a mature parent cell - This is correct.
• (iii) It involves union of two types of gametes - This is incorrect.

 So, the correct answer is (ii)It involves a mature parent cell.

Vegetative reproduction is an asexual method of reproduction in which mitotic cell division leads to the formation of new plants obtained from the parts of old plants like stem, roots and leaves.

• I. Involves two individuals   - This is incorrect.
• II. Daughter cells are genetically identical to the parent - This is correct.
• III. The cell division is only mitotic - This is correct.

So, the correct answer is (iii) II and III only.

BINARY FISSION IN AMOEBA Parent Cell Nucleus Divides Cytoplasm Divides Two Daughter Cells BINARY FISSION IN LEISHMANIA

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Class 10 Science: Case Study Chapter 8 How Do Organisms Reproduce PDF Download

In CBSE Class 10 Science Paper, Students will have to answer some questions based on  Assertion and Reason . There will be a few questions based on case studies and passage-based as well. In that, a paragraph will be given.

Here we are providing you with Class 10 Science Chapter 8 How Do Organisms Reproduce Case Study Questions, by practicing this Case Study and Passage Based Questions will help you in your Class 10th Board Exam.

Case Study Chapter 8 How Do Organisms Reproduce

Here, we have provided case-based/passage-based questions for Class 10 Science  Chapter 5 Periodic Classification of Elements

Case Study/Passage Based Questions

Question 1:

The male reproductive system consists of portions that produce the germ cells and other portions that deliver the germ cells to the site of fertilization. Testes are located outside the abdominal cavity in the scrotum because sperm formation requires a lower temperature than normal body temperature. It also has a role of secretion of male sex hormone which brings changes in appearance seen in boys at the time of puberty. Vas deferens unites with a tube coming from the urinary bladder. The urethra is a common passage for sperms and urine. The prostate gland and seminal vesicles add their secretions so that sperms are now in a fluid.

(i) Name the sex hormone associated with males. (a) Testosterone (b) Progesterone (c) Oestrogen (d) None of these

Answer: (a) Testosterone

(ii) Which of the following statements is incorrect ? (a) Sperms are present in a fluid (b) Fluid provides nutrition to sperms (c) Fluid makes easier transportation of sperms (d) Fluid helps to bind the sperms together

(iii) Testes are located outside the abdominal cavity in scrotum because (a) sperms formation requires higher temperature than body temperature (b) sperms formation requires lower temperature than body temperature (c) it is easier to transport sperms from the scrotum (d) None of these

Answer: (b) sperms formation requires lower temperature than body temperature

(iv) Which of the following statement is incorrect? (a) Sperms and urine has a common passage from urethra.

(b) Sperms have long tail that helps them to move forward. (c) Sperms contain genetic material. (d) Sperms formation requires 1–3°C higher temperature than normal body temperature.

Answer: (d) Sperms formation requires 1–3°C higher temperature than normal body temperature.

(v) What is the nature of semen? (a) slightly acidic (b) Neutral (c) Slightly basic (d) Strongly basic

Answer: (c) Slightly basic

Question 2:

Rohit collected some pond water which was dark green in color in a test tube. She took out green-colored mass from it and separated its filaments by using needles. She broke some filaments into small fragments and put them in a Petri dish containing clean water. She observed that after a few days the small fragments gave rise to complete filaments.

2.1) What do you think the mass of green filament was ?  (a) It was a mass of Spirogyra filament. (b) It was a colony of Volvox algae. (c) It was large brown algae. (d) It was a mass of fungal filaments

Answer:(a) It was a mass of Spirogyra filament. ​

2.2) Organisms that reproduces in similar ways as Spirogyra is : (a) yeast (b) hydra (c) Planaria (d) Sea anemone

Answer: (d) Sea anemone ​

2.3) The small fragment gave rise to new filament. What does it indicate  ? (a) Spirogyra reproduces asexually through budding. (b) Spirogyra reproduces asexually through spore formation. (c) Spirogyra reproduces asexually through fragmentation. (d) Spirogyra reproduces asexually through fission

Answer: (c) Spirogyra reproduces asexually through fragmentation. ​

2.4) Which among the following organisms do not reproduce by fragmentation ? (a) Riccia  (b) Selaginella (c) Aurelia (d) Marchantia

Answer: (c) Aurelia. ​

2.5) Select the correct statement from the following. (a) Only multicellular organisms can undergo fragmentation. (b) Both unicellular and multicellular organisms can undergo fragmentation. (c) Fragmentation is sexual mode of reproduction. (d) Fragmentation is found only in algae

Answer: (a) Only multicellular organisms can undergo fragmentation ​

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NCERT Solutions for Class 10 Science Chapter 8 How do Organisms Reproduce?

Chapter 8 How do Organisms Reproduce? Class 10 NCERT Solutions

Ncert solutions for class 10 science chapters:.

Where does fertilization take place in human females?

What is cross-pollination, what is ovulation, what is menopause, what is asexual reproduction, contact form.

Extra Questions for Class 10 Science Chapter 8 How Do Organisms Reproduce

Get extra questions for Class 10 Science Chapter 8 How Do Organisms Reproduce with PDF. Our subject expert prepared these solutions as per the latest NCERT textbook. These extra questions will be helpful to revise the important topics and concepts. You can easily download all the questions and answers in PDF format from our app.

How Do Organisms Reproduce Class 10 Science Extra Questions with Answers

Question 1: What is the effect of DNA copying which is not perfectly accurate on the reproduction process?

Answer: DNA copying is not perfectly accurate and the resultant errors are a source of variations in populations of organisms.

Question 2: Mention the mode of reproduction used by (a) Amoeba (b) Planaria.

Answer: Mode of reproduction used by (a) Amoeba is Binary fission. (b) Planaria is Regeneration.

Question 3: Name the information source of making proteins in the cell. State two basic events in reproduction.

Answer: The DNA in the cell nucleus is the information source of making proteins.

The two basic events in reproduction are: (i) Creation of a DNA copy, (ii) Additional cellular apparatus by the cell involved in the process.

Question 4: State the method used for growing rose plants.

Answer: Artificial methods of vegetative propagation like cutting are used to grow rose plants.

Question 5: State what type of method is used for growing jasmine plant.

Answer: Artificial methods of vegetative propagation like layering is used for growing jasmine plant.

Question 6: Name the largest cell present in the human body.

Answer: The largest cell present in the human body is ovum.

Question 7: What is ‘reproduction’? Mention the importance of DNA copying in reproduction.

Answer: Reproduction is the process of producing new individuals of the same species by existing organisms of a species, i.e. parents. The importance of DNA copying in reproduction are as follows:

(i) DNA copying is called DNA replication. In this process, one copy each of replicated DNA will be passed to daughter cells.

(ii) Variations may be introduced during DNA copying. This inbuilt tendency for variation during reproduction forms the basis of evolution.

Question 8: “Variations that confer an advantage to an individual organism only will survive in a population.” Justify.

Answer: It is because the chances of survival depend on the nature of variations and different individuals have different kinds of advantages.

For example : A bacteria that can withstand heat will survive better in a heat wave, i.e. the organisms that are fit in the competitive environment and with great variations will be able to survive and adapt. Thus, more offsprings and population with genetic variations will survive.

Question 9: Name one sexually transmitted disease each caused due to bacterial infection and viral infection. How can these be prevented?

Answer: Sexually transmitted disease caused due to (i) Bacterial infection is gonorrhoea, and (ii) Viral infection is AIDS (Acquired Immune Deficiency Syndrome). These diseases can be prevented by responsible sexual behaviour such as use of condom during intercourse, etc.

Question 10: (a) In the human body what is the role of (i) seminal vesicles, and (ii) prostate gland? (b) List two functions performed by testis in human beings.

Answer: (a) The role of seminal vesicles and the prostate gland are as follows: (i) Seminal vesicles produce seminal plasma which is in the form of fluid makes the transport of sperms smooth. (ii) Prostate gland secretes prostatic fluid that keeps the sperms alive and helps them to swim vigorously.

(b) Two functions performed by testis in human beings are as follows: (i) Formation of sperms takes place in testis. (ii) They secrete the hormone testosterone which regulates the formation of sperms and brings changes in appearance of boys at the time of puberty.

Question 11: What is regeneration? State a reason why a more complex organism cannot give rise to new individuals through this method.

Answer: Regeneration is the ability of a fully differentiated organism to give rise to new individual organisms from its body parts. More complex organisms cannot give rise to new individuals through regeneration because: (i) their body is highly complicated. (ii) there are specific organs to do specific functions. (iii) there is a labour division in the body of complex organisms. (iv) regeneration is carried out by specialised cells which are not present in complex organisms.

Question 12: What is reproduction? What are its two types? Which one of the two confers new characteristics on the offsprings and how?

Answer: Reproduction is the process of producing new individuals of the same species by existing organisms of a species, i.e., parents. Its two types are: Asexual reproduction and Sexual reproduction. Sexual reproduction confers new characteristics on the offspring due to variation in DNA copying.

Question 13: List any four reasons for vegetative propagation being practised in the growth of some type of plants.

Answer: (i) Vegetative propagation is a cheaper, easier and more rapid method of propagation in plants than growing plants from their seeds.

(ii) Better quality of plants can be maintained by this method.

(iii) It results in propagation of those plants which do not produce viable seeds or produce seeds with prolonged period of dormancy.

(iv) The plants generated from vegetative means are more uniform and genetically similar to the parent stock.

Question 14: Write differences between binary fission and multiple fission in a tabular form as observed in cells of organisms.

Question 15: List any four modes of asexual reproduction.

Answer: Four modes of asexual reproduction are—Binary fission in Amoeba, Fragmentation in Spirogyra, Regeneration in Planaria and Budding in Hydra.

Question 16: Why is DNA copying an essential part of the process of reproduction?

Answer: DNA copying is an essential part of the process of reproduction because: (i) DNA copying provides cellular apparatus in the daughter cells. (ii) DNA in daughter cells will be able to control the functioning of daughter cells. (iii) DNA copies will retain the traits.

Question 17: State one genetically different feature between sperms and eggs of humans. What is its consequence?

Answer: The sex chromosome of human male is XY. A sperm of human male carries either an X chromosome or one Y chromosome.

The sex chromosome of human female is XX and hence, the egg always carries the X chromosome.

If a sperm carrying X chromosome fertilises an egg which carries X chromosome, then the’ child born will be a girl. If a sperm carrying Y chromosome fertilises an egg which carries X chromosome, then the child born will be a boy.

Question 18: List two advantages of vegetative reproduction practised in case of an orange plant.

Answer: Two advantages of practising vegetative reproduction in orange plants are: (i) The oranges produced are similar in size and shape. (ii) Many oranges do not produce viable seeds and hence, vegetative method is good alternative.

Question 19: How does growing embryo get nutrition from the mother’s blood?

Answer: The embryo gets nutrition from the mother’s blood with the help of a special tissue called placenta. This is a disc which is embedded in the uterine wall and transfers glucose and oxygen from the mother to the embryo.

Question 20: Define the term puberty. List two changes observed in girls at the time of puberty.

Answer: The period, when the rate of general body growth begins to slow down and reproductive tissues begin to mature, is called puberty.

Two changes observed in girls at the time of puberty are: (i) The breast size begin to increase (ii) Menstruation starts.

Question 21: What is meant by asexual reproduction? List its any two different forms.

Answer: Asexual reproduction is the process of producing new organism from a single parent without the involvement of sex cells. Fission and fragmentation are two different forms of asexual reproduction.

Question 22: Name an organism which reproduces by spore formation. List three Conditions favourable for spores to germinate and grow.

Answer: Rhizopus reproduces by spore formation. Conditions favourable for spore formation are: (i) Cool place, (ii) Moist place and (iii) Dark place.

Question 23: “DNA copies generated during reproduction will be similar but may not be identical to the original.” Justify this statement.

Answer: DNA copies generated will be similar, but may not be identical to the original as some variations are so drastic that new DNA copy cannot work with the cellular apparatus it inherits. Such a newborn cell will simply die. Therefore, there could be many other variations in the DNA copies that would not lead to such a drastic outcome. Thus, the surviving cells are similar but slightly different from each other. This tendency of variation during reproduction is the basis for evolution.

Question 24: List two advantages of practising vegetative propagation in plants. Select two plants raised by this method from the list given below: Banana, Gram, Pea, Rose, Tomato, Wheat.

Answer: Advantages of vegetative propagation are:

• Plants raised by vegetative propagation can bear fruits and flowers earlier.
• Plants produced are genetically similar.

Banana and Rose can be raised by vegetative method.

Question 25: List the parts of human male reproductive system which contribute fluid to the semen. State two advantages semen offers to the sperms.

Answer: Prostate glands and seminal vesicles add fluid in the vas deferens. This makes transportation of sperms easier and also provides nutrition to the sperms.

Question 26: Name the two types of germ-cells present in human beings. How do they structurally differ from each other? Give two differences.

Answer: The two types of germ-cells present in human beings are sperm and ova. The sperm of human have either X or Y chromosome. The ova always carry X chromosome. The sperm is structurally long with a tail. The ova is round in structure.

Question 27: (i) What is fertilisation? Distinguish between external fertilisation and internal fertilisation. (ii) What is the site of fertilisation in human beings?

Answer: (i) Fertilisation is defined as the fusion of a male gamete (sperm) with a female gamete (an ovum or egg) to form a zygote during sexual reproduction.

(ii) The site of fertilisation in human beings is in the fallopian tube of female reproductive system.

Question 28: Define the terms unisexual and bisexual giving one example of each.

Answer: Unisexual is the plant whose flowers contain either stamens or carpels but not both. Example: Papaya, Watermelon.

Bisexual is the plant whose flowers contain both stamens and carpels. Example: Hibiscus, Mustard.

Question 29: Differentiate between ‘self-pollination’ and ‘cross-pollination’. Describe double fertilisation in plants.

During fertilisation in plants, the following events take place: (i) One of the male gamete fuses with the female gamete present in the embryo sac. (ii) The other male gamete fuses with the two polar nuclei in the embryo sac. The first fusion product gives rise to the zygote while the second one forms the endosperm. The process of two fusions occurring in the embryo sac is called double fertilisation.

Question 30: (a) Explain the terms: (i) Implantation (ii) Placenta (b) What is the average duration of human pregnancy?

Answer: (a) (i) Implantation: The embedding of a fertilised mammalian egg (embryo) into the inner thick wall of the uterus (womb) where it will continue its development is called implantation.

(ii) Placenta: It is a complex double-layered spongy vascular tissue in human female formed by the joint activity of maternal and foetal tissues in the wall of uterus that is meant for attachment, nourishment and waste disposal for the foetus.

(b) The average duration of human pregnancy is 40 weeks or 280 days.

Question 31: What are sexually transmitted diseases? Name four such diseases. Which one of them damages the immune system of human body?

Answer: Sexually Transmitted Diseases (STDs) are the diseases which are spread by sexual contact from an infected person to a healthy person. They are caused by various microorganisms that live in warm and moist environments of the vagina, urethra, anus and mouth.

The four sexually transmitted diseases are: (i) Gonorrhoea (ii) Syphilis (iii) Trichomoniasis (iv) AIDS (Acquired Immune Deficiency Syndrome).

AIDS damages the immune system of human body.

Question 32: Write the full form of DNA. Name the part of the cell where it is located. Explain its role in the process of reproduction of the cell.

Answer: The full form of DNA is deoxyribonucleic acid. It is the genetic material found in the chromosomes, which are present in the nucleus of a cell.

Role of DNA in the process of reproduction of the cell:

DNA plays an important role in the reproduction of a cell. The reproducing cell produces an identical copy of DNA through some cellular mechanism. Since the newly formed copy of DNA lacks an organised cellular structure, the cell gets divided to provide cell cover to the newly formed DNA. Thus, two daughter cells are formed from the single cell as a result of the copying of DNA.

Question 33: Explain vegetative propagation with the help of two examples. List two advantages of vegetative propagation.

Answer: In vegetative propagation, new plants are obtained from the parts of old plants like stems, roots and leaves, without the help of any reproductive organ.

There are two ways of vegetative propagation: (a) Natural Vegetative Propagation, and (b) Artificial Vegetative Propagation.

Natural vegetative propagation by leaves: The fleshy leaves of Bryophyllum bear adventitious buds in the notches along the leaf margin.

Grafting: In this method of reproduction, two plants of closely related varieties are joined together so that they live as one plant.

• The portion of a plant that is grafted on the other plant is called scion, and the plant in which grafting is performed is called the stock.
• This method is applied to improve variety of fruits like mango, apple, peas, citrus and guava. advantages of vegetative propagation are:

(i) Vegetative propagation is a cheaper, easier and more rapid method of propagation in plants than growing plants from their seeds. (ii) Better quality of the plants can be maintained by this method.

Question 34: List differences between pollination and fertilisation.

Question 35: What does HIV stand for? Is AIDS an infectious disease? List any four modes of spreading AIDS.

Answer: HIV stands for Human Immunodeficiency Virus. Yes, AIDS is an infectious disease.

Four modes of spreading AIDS are as follows: (i) By having sexual contact with an infected person. (ii) By the transfusion of blood from an infected person. (iii) Through infected needles used for injection. (iv) Through the placenta from the mother to child during pregnancy.

Question 36: Expand AIDS. List any four methods of prevention (control) of AIDS.

Answer: AIDS stands for Acquired Immune Deficiency Syndrome.

Four methods of prevention or control of AIDS are as follows: (i) Use condom during sex. (ii) Avoid sharing of needles. (iii) Test blood for AIDS before transfusion. (iv) Avoid sexual contact with unknown person.

Question 37: (a) List any four reasons for adopting contraceptive methods. (b) If a woman is using Copper-T, will it help in protecting her from sexually transmitted diseases? Why?

Answer: (a) Four reasons for adopting contraceptive methods are: (i) To increase the gap between, two children. (ii)To prevent unwanted pregnancy. (iii)To prevent transmission of STDs. (iv)To control population growth. (b) If a woman is using a copper-T, it will not help in protecting her from sexually transmitted diseases. Copper-T prevents only implantation in the uterus.

Question 38: Explain the following methods of contraception giving one example of each: (i) Barrier method (ii) Hormonal imbalance method (iii) Surgical method.

Answer: (i) Barrier Method: In this method, physical devices such as condoms, diaphragm and cervical caps are used. These devices prevent the entry of sperm in the female genital tract during copulation, thus acting ‘ as a barrier between them.

(ii) Hormonal Imbalance Method: In this method, specific drugs are used by females, which are of two types: oral pills and vaginal pills. Oral pills contain hormones which stop the ovaries from releasing ovum into the fallopian tube. These pills are also called oral contraceptives (OCs) which act by changing the hormonal balance of the body so that eggs are not released and fertilisation cannot occur. The use of Intrauterine Contraceptive Devices (IUCDs) prevents implantation in the uterus. This device is copper-T placed safely inside the uterus by a doctor or nurse.

(iii) Surgical Method: In this method, a small portion of vas deferens in male and the fallopian tube in ‘ female is surgically removed or tied. It is called vasectomy in males and tubectomy in females. In this case, if the vas deferens in male is blocked, sperm transfer will be prevented and if the fallopian tube in the female is blocked, the egg will not be able to reach the uterus, thus fertilisation will not take place.

Question 39: List and explain in brief three methods of contraception.

Answer: Methods of contraception are:

• Use of condom for penis or for vagina as a mechanical barrier for the sperms to reach the egg.
• Use of oral pills which change the hormonal balance so that eggs are not released.
• Surgical method where either the vas deferens of male is blocked or the fallopian tube of female is blocked.

Question 40: What is AIDS? Which microbe is responsible for AIDS infection? State one mode of transmission of this disease. Explain in brief one measure for the prevention of AIDS.

Answer: AIDS is the Acquired Immune Deficiency Syndrome. It is caused by a virus called Human Immunodeficiency Virus. AIDS is transmitted by sexual contact with an infected person. AIDS can be prevented by avoiding sexual contact with infected person or by using condom during sex.

Question 41: (a) Name the parts labelled A, B, C, D and E.

(b) Where do the following functions occur? (i) Production of an egg (ii) Fertilisation (iii) Implantation of zygote.

(c) What happens to the lining of uterus: (i) before release of a fertilised egg? (ii) if no fertilisation occurs?

Answer: (a) A – Oviduct or Fallopian tube; B – Ovary; C – Uterus; D – Cervix; E – Vagina.

(b) (i) Ovaries; (ii) Fallopian tube; (iii) Lining of the uterus.

(c) (i) The lining of uterus becomes (ii) The lining of uterus slowly breaks and comes out through the vagina as blood and mucous, if no fertilisation occurs.

Question 42: (a) Draw a diagram showing germination of pollen on stigma of a flower. (b) Label pollen grain, male germ- cells, pollen tube and female germ-cell in the above diagram. (c) How is zygote formed?

Answer: (a) and (b)

(c) Zygote is formed when male gamete, Le. sperm fuses with female gamete, i.e. ovum.

Question 43: Draw a longitudinal section of a flower and label the following parts: (i) Part that produces pollen grain. (ii) Part that transfers male gametes to the female gametes. (iii) Part that is sticky to trap the pollen grain. (iv) Part that develops into a fruit.

Question 44: (a) Explain the role of placenta in the development of human embryo.

(b) Give example of two bacterial and two viral sexually transmitted diseases. Name the most effective contraceptive which prevents spread of such diseases.

Answer: (a) Role of placenta in the development of human embryo: A special tissue develops between the uterine wall and the embryo (foetus) called placenta, where exchange of nutrients, glucose and oxygen takes place. The developing embryo will also generate waste substances which can be removed by transferring them into the mother’s blood through the placenta. The development of the child inside the mother’s blood takes approximately nine months.

(b) Sexually transmitted diseases (STDs) transmitted by bacteria are: (i) Gonorrhoea (ii) Syphilis

STDs transmitted by virus: (i) AIDS (ii) Genital warts

The most effective contraceptive which prevents the spread of these diseases is by the use of mechanical barriers such as physical devices like condoms.

Question 45: Describe in brief the role of (i) testis (ii) seminal vesicle, (iii) vas deferens, (iv) ureter and (v) prostate gland in human male reproductive system.

Answer: (i) Testis: Testes are oval shaped primary reproductive organs in men. The function of testes is to produce sperms and male sex hormone testosterone. The scrotum provides optimal temperature for the formation of sperms.

(ii) Seminal vesicle: Seminal vesicles are a pair of thin walled muscular elongated sac which secrete fluid for nourishment of sperms.

(iii) vas deferens: The sperms are carried by a long tube called vas deferens to organs called seminal vesicles where the sperms get nourishment and stored.

(iv) Ureter It is the tube that carries urine from kidney to the urinary bladder. In humans, there are two ureters, one attached to each kidney.

(v) Prostate glands: Prostate glands produce a fluid which is released in the urethra along with secretion of seminal vesicles for nourishment and transportation of sperms.

Question 46: Draw a diagram of a human female reproductive system and label the part (i) that produces egg (ii) where fusion of egg and sperm take place (iii) where zygote is implanted What happens to human egg when it is not fertilised?

If the egg is not fertilised, the thick and nourishing lining of the uterus breaks and comes out through vagina as blood and mucous.

Question 47: State in brief the changes that take place in a fertilised egg (zygote) till birth of the child in the human female reproductive system. What happens to the egg when it is not fertilised?

Answer: The egg gets fertilised in the oviduct. The fertilised egg, the zygote gets implanted in the lining of the uterus and starts dividing. The uterus prepares itself every month to receive and nurture the growing embryo. The lining thickens and is richly supplied with blood to nourish the growing embryo.

The embryo gets nutrition from the mother’s blood with the help of a special tissue called placenta. The development of the child inside the mother’s body takes approximately nine months. On completion of 9 months, the child is born as a result of rhythmic contractions of the muscles in the uterus.

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How do Organisms Reproduce Class 10 Extra Questions with Answers Science Chapter 8

In this page, you can find CBSE Class 10 Science Chapter 8 Extra Questions and Answers How do Organisms Reproduce Pdf free download, NCERT Extra Questions for Class 10 Science will make your practice complete.

Class 10 Science Chapter 8 Extra Questions and Answers How do Organisms Reproduce

Extra Questions for Class 10 Science Chapter 8 How do Organisms Reproduce with Answers Solutions

How do Organisms Reproduce Extra Questions Very Short Answer Type

Question 1. What is the effect of DNA copying which is not perfectly accurate in the reproduction process? Answer: The DNA copying which is not perfectly accurate in the reproduction process results in variations in populations for better survival of the species.

Question 2. What methods will you use for growing jasmine and rose plants? Answer: For growing jasmine plants, layering method will be used and for growing rose plants, cutting and grafting methods will be used.

Question 3. Name the part of Bryophyllum where the buds are produced for vegetative propagation. Answer: In Bryophyllum, the buds are produced in leaf notches.

Question 4. Which parts of plants can grow vegetatively? Answer: Modified stems like onion bulbs, runners of doob grass, ginger rhizomes, potato tubers, root tubers of sweet potato and dahlia, stem cutting of plants like rose and leaves of plants like Bryophyllum can be grown vegetatively.

Question 5. Can you consider cell division as a type of reproduction in a unicellular organism? Give one reason. Answer: Yes, because it results in the formation of two daughter cells, i.e., it results in the production of more individuals of the organism.

Question 6. What is the function of pollen grains in flowers? Answer: Pollen grains are the male gametes which fertilise the egg cell present in the ovule of a flower.

Question 7. Write the various methods of cross-pollination. Answer: Various methods of cross-pollination are entomophily (insect pollination), anemophily (wind pollination), hydrophily (water pollination) and zoophily (animal pollination).

Question 8. Why cannot fertilisation take place in flowers if pollination does not occur? Or Why is fertilisation not possible without pollination? Answer: In a flower, fertilisation requires both male and female gametes. If pollination does not occur, male gametes will not be available hence fertilisation cannot take place.

Question 9. Explain the role of cotyledon and plumule in germination. Answer: Cotyledon stores food and the plumule acts as future shoot.

Question 10. Is the chromosome number of zygote, embryonal cells and adult of a particular organism always constant? How is the constancy maintained in these three stages? Answer: Yes, the constancy is maintained because cells in all these three structures undergo only mitotic divisions.

Question 11. In a bisexual flower inspite of the young stamens being removed artificially, the flower produces fruit. How is it possible? Answer: This is because the pistil is intact due to which cross-pollination takes place leading to fertilisation and formation of fruit.

Question 12. What is gametogenesis? Answer: Formation of sperms in testes and ova in ovary is called gametogenesis.

Question 13. In a tobacco plant, the male gametes have twenty-four chromosomes. What is the number of chromosomes in the female gamete? What is the number of chromosomes in the zygote? Answer: Number of chromosomes in female gamete is 24 and in zygote it is 48.

Question 14. How is the sperm genetically different from the egg? Answer: Sperms contain either X or Y chromosome whereas an egg will always have an X chromosome.

Question 15. What would be the ratio of chromosome number between an egg and its zygote? How is the sperm genetically different from the egg? Answer: The ratio is 1 : 2 Sperms contain either X or Y chromosome whereas an egg will always have an X chromosome.

Question 16. List two functions performed by the testis in human beings. Answer: Functions of testis:

• To produce sperms.
• To produce male sex hormone/testosterone.

Question 17. List two functions of ovary of human female reproductive system. Answer:

• To produce female gamete.
• To secrete female hormones.

Question 18. Name the life process of an organism that helps in the growth of its population. Answer: Reproduction helps in the growth of the population.

Question 19. What happens when a mature Spirogyra filament attains considerable length? Answer: When a mature Spirogyra filament attains considerable length its filament breaks up into smaller fragments and each fragment grows into a new filament or individual.

Question 20. What will happen if all the organisms in one trophic level are destroyed? Answer: The transfer of food (energy) tapes place through various steps in the food chain known as trophic levels. In case of destruction of all organisms of one trophic level, the ecosystem will get unstable and eventually all life forms will die.

Question 21. What happens when a Planaria gets cut into two pieces? Answer: Each piece regenerates into a new Planaria.

Question 22. Name the method by which Hydra reproduces. Is this method sexual or asexual? Answer: Hydra reproduces by budding or regeneration. It is a method of asexual reproduction.

Question 23. Name the method by which Spirogyra reproduces under favourable conditions. Is this method sexual or asexual? Answer: Spirogyra reproduces by fragmentation. It is an asexual method.

Question 24. How does Planaria reproduce? Is this method sexual or asexual? Answer: Planaria reproduces by regeneration. This method is asexual.

Question 25. How does Plasmodium reproduce? Is this method sexual or asexual? Answer: Plasmodium reproduces by multiple fission. This method is an asexual means of reproduction.

Question 26. Name the male and female gametes in animals. Answer: In animals, male gametes are called sperms while female gametes are called eggs or ova.

Question 27. Why are testes placed outside the abdominal cavity in the scrotal sac? Answer: Testes are placed outside the body cavity in the scrotal sac because it requires a temperature 2°C lower than the normal body temperature for production of sperms.

Question 28. What is hymen? Answer: It is a thin fold of membrane which surrounds or partly closes the external vaginal opening.

Question 29. What is funeral of unfertilised egg? Answer: Menstruation is also called funeral of egg since it is not fertilised.

Question 30. What is gestation? Answer: The period of development of foetus in the uterus until birth is called gestation. It is of 9 months duration (i.e., 280 days or 40 weeks from the first day of the last menstrual cycle) in human beings.

Question 31. Define parturition. Answer: The birth of the fully developed foetus (childbirth) is called parturition.

Question 32. Name the causative agent of the disease ‘Kala-azar’ and its mode of asexual reproduction. Answer: The causative agent of Kala-azar is Leishmania and the mode of asexual reproduction is binary fission.

Question 33. Name the parts of a bisexual flower that are not directly involved in reproduction. Answer:

• Sepals/calyx
• Petals/Corolla

Question 34. List two unisexual flowers. Answer: Watermelon and papaya are unisexual flowers.

Question 35. What is DNA? Answer: DNA is the carrier of hereditary information from parents to the next generation.

Question 36. Write names of one male and one female sex hormone. Answer: Male sex hormone is testosterone and female sex hormone is oestrogen.

Question 37. Illustrate with example the division and fragmentation method of reproduction in living organisms. Answer: Fragmentation: It is a type of a sexual reproduction observed in multicellular organisms on maturation break up into two or more small fragments or pieces. Each fragment subsequently grows to form a completely new organism. Fission: The process of reproduction by which a unicellular organism splits into two or more than two separate daughter cells is called fission. Generally, it is of two types:

• Binary fission.
• Multiple fission.

Question 38. What is syngamy? Answer: One male gamete fuses with one female gamete or egg. This process of fusion of male and female nuclei is called syngamy.

Question 39. What are those organisms called which bear both the sex organs in the same individual? Give one example of such organism. Answer: Organisms bearing both the sex organs in the same individual are called bisexual. Example, Hydra, Mustard.

Question 40. Give an example of a unisexual and bisexual flower. Answer: Cucumber is a unisexual flower and hibiscus is a bisexual flower.

Question 41. Where is the zygote located in the flower after fertilisation? Answer: Zygote is located inside the ovule which is present in the ovary.

Question 42. Where do the following functions occur?

• Production of an egg
• Fertilisation
• Implantation of zygote
• In fallopian tube
• In uterus (uterine wall)

Question 43. What changes are observed in the uterus if fertilisation does not occur? Answer: If fertilisation does not occur, the thick and spongy lining of the uterus slowly breaks and comes out through the vagina as blood and mucus.

Question 44. Give a reason for the statement- Since the ovary releases one egg every month, the uterus also prepares itself every month by making its lining thick and spongy. Answer: The lining of uterus becomes thick for nourishing the embryo if fertilisation takes place and egg reaches the uterus.

Question 45. What is menopause? Answer: The period of permanent cessation of menstruation in females, usually occurring between the age of 45 and 50 is called as menopause.

Question 46. Name the organs producing sperms and ova respectively in humans. Answer: Testis produces sperms and ovary produces ova in humans.

Question 47. What is fertilisation? Where does it occur in a human female? Answer: Fertilisation is the fusion of sperm or male gamete and female gamete. It takes place in the oviduct or fallopian tube of human female.

How do Organisms Reproduce Extra Questions Short Answer Type

Question 1. Define the terms unisexual and bisexual giving one example of each. Answer: Unisexual: In most of the animals including humans, male and female reproductive organs are in different individuals. Such animals are called unisexual. Bisexual: In some animals like tapeworm, liver fluke, earthworm, leech, etc., the male and female reproductive organs are found in a single individual. Such organisms are called bisexual (hermaphrodite). The flower may be unisexual (e.g., papaya, watermelon) when it contains either stamens or carpels and bisexual (e.g., Hibiscus, mustard) when it contains both stamens and carpels.

Question 2. What is a clone? Why do offsprings formed by asexual reproduction exhibit remarkable similarity? Answer: Clone refers to the offspring of an organism formed by asexual method of reproduction. Since they possess exact copies of the DNA of their parent, clones exhibit remarkable similarity.

Question 3. Why does bread mould grow profusely on a moist slice of bread rather than on a dry slice of bread? Answer: Moisture is an important factor for the growth of hyphae. Moistened bread slice offers both moisture and nutrients to the bread mould, hence it grows profusely. Dry slice of bread offers nutrients but not moisture hence hyphae fail to grow.

Question 4. Explain the roles of gametes and zygote in sexual reproduction, Answer: The two fusing gametes posses characters of their parents in their DNA. Fertilisation brings characters of both parents into one zygote cell. Zygote is the first cell of the next generation. It divides to form an embryo which subsequently grows into a new individual.

• Male gamete forming part-anther/stamen
• Female gamete forming part-pistil/ovary/ovule

Question 5. Describe the structure of a pollen grain. Answer: Stamens produce pollen grains that are yellowish in colour. Pollen grain is unicellular and haploid. It has two layers, the thicker outer one is called exine, which is thin at places called germ pores and inner thin layer is called intine.

Question 6. In a germinating seed, which parts are known as future shoot and future root? Mention the function of cotyledon. Answer: In a germinating seed, plumule in known as future shoot and ridicule is known as future root. The function of cotyledon is to store food for the future plant or embryo.

Question 7. Identify the following parts of a flower:

• Part hat produces pollen grain
• Part that transfers male gametes
• Part that is sticky to trap
• Part the develops into a fruit.

Question 8. What is puberty? Answer: The period of adolescence when the reproductive organs become functional is termed as puberty. It is accompanied by development of secondary sexual characters both in males and females.

Question 10. Give two reaosns for the appearance of variations among the progeny formed by sexual reproduction. Answer:

• Sexual reproduction involves two parents with different sets of characters.
• The gene combinations are different in gametes.

Question 11. What are the benefits of using mechanical barriers during sexual act? Answer: Mechanical barriers like condom prevent the sperms from reaching the egg. Thus it is an effective method to avoid pregnancy. It also prevents transmission of infections during sexual act.

Question 12. Write one main difference between asexual and sexual mode of reproduction. Which species is likely to have comparatively better chances of survival the one reproducing asexually or the one reproducing sexually? Justify your answer. Answer: Asexual reproduction does not involve genetic fusion while sexual reproduction involves fusion of male and female gametes to form a zygote. Species reproducing sexually have better chances of survival. This is because sexual reproduction gives rise to more variations which are essential for evolution as well as for the survival of species under unfavourable conditions.

Question 13. Why is DNA copying an essential part of the process of reproduction? What are the advantages of sexual reproduction over asexual reproduction? Answer: DNA copying is essential because it makes the transmission of characters from parents to the next generation possible.

Advantages of sexual reproduction over asexual reproduction: Sexual reproduction gives rise to variations, which are essential for evolution as well as for the survival of species under unfavourable conditions.

Question 14. Trace the path of sperm during ejaculation and mention the gland and their functions associated with the male reproductive system. Answer: Sperm comes out from testis into the vas deferens and then passes through urethra before ejaculation. The secretion of seminal vesicle and prostate glands provide nutrition to the sperms and also facilitate their transport.

Question 15. What changes are observed in the uterus subsequent to implantation of young embryo? Answer: The uterine wall thickens that is richly supplied with blood. A special tissue called placenta develops which connects embryo to the uterine wall that provides nutrients and oxygen to it.

Question 16. Give two reasons for avoiding frequent pregnancies by women. Answer: Frequent pregnancies by women are avoided due to the following reasons:

• It has adverse effect on the health of women.
• It increases the rate of the population of our country.

Question 17. Reproduction is one of the most important characteristics of living beings. Give three reasons in support of the statement. Answer:

• Reproduction is important for continuation of species or perpetuation of species.
• It promotes diversity of characters or helps to show the variations which enhance the survival chances.
• It increases population of a species.

Question 18. Suggest three contraceptive methods to control the size of human population which is essential for the health and prosperity of a country. State the basic principle involved in each. Answer: The methods of contraception are:

• Barrier method or mechanical method (Condom/Diaphragm): Prevents the meeting of sperems and ova.
• Chemical method (Oral pills): Changes the hormonal balance of the female partner so that the eggs are not released.
• Surgical method: The vas deference in males is blocked (vasectomy) or the fallopian tube (oviduct) in females is blocked (tubectomy) to prevent the transfer of sperms or egg and hence no fertilisation takes place.
• IUCDs/Loop or the copper-Țis placed in the uterus to prevent pregnancy. (Any three)

Question 19. List three techniques that have been developed to prevent pregnancy. Which one of these techniques is not meant for males? How does the use of these techniques have a direct impact on the health and prosperity of a family? Answer: Three techniques to prevent pregnancy are barrier method, chemical method and surgical method. Chemical method is not meant for males: Use of these techniques helps in maintaining health of the woman. Also, parents can provide more attention and quality resources to the children.

Question 20. List four points of significance of reproductive health in a society. Name any two areas related to reproductive health which have improved over the past 50 years in our country. Answer: Significance of reproductive health in a society:

• It prevents the spread of various sexually transmitted diseases such as AIDS, syphilis, etc.
• Individuals with sound reproductive health produce better offspring which have better chances of survival.,
• Better sex education and awareness help to maintain the population and prevent a population explosion.
• Unwanted and teen pregnancies can be avoided. The reproductive health in India has improved tremendously over the past 50 years.
• Family planning
• Mortality rate.

Question 21. List four categories of contraceptive methods. State in brief two advantages of adopting such preventive methods. Answer: The categories of contraceptive methods are:

• Barrier method (Condoms)
• Surgical method
• Withdrawl method
• Calendar method
• Hormonal method
• IUCD/Copper-T/Loop

Two advantages of adopting preventive methods are:

• It helps in maintaining the health of women.
• It helps in preventing STDs especially AIDS.
• It helps in birth control.
• Parents can give more attention to children.

Question 22. Name the reproductive parts of an angiosperm. Where are these parts located? Explain in brief the structure of its female reproductive parts. Answer: In an angiosperm, the male reproductive part is androecium or stamen and the female reproductive part is the gynoecium or carpel. These parts are located in the flower. The gynoecium (carpel) has three parts:

• Stigma: It is the uppermost part which has a sticky surface to which pollen grain stick during pollination.
• Style: It is the middle elongated part which connects the stigma to the ovary.
• Ovary: It is the bottom swollen part in which female gametes are formed.

Question 23. (i) Name the following: (a) Threadlike non-reproductive structures present in Rhizopus. (b) ‘Blobs’ that develop at the tips of the non-reproductive threads in Rhizopus. (ii) Explain how these structures protect themselves and what is the function of the structures released from the ‘blobs’ in Rhizopus. Answer: (i) (a) Hyphae/mycelium, (b) Sporangia.

(ii) These structures are protected by thick walls. These structures germinate into new individuals under favourable conditions.

Question 25. What is asexual reproduction? Write the process of budding in Hydra. Answer: Asexual reproduction is the mode of reproduction used by single organisms or parents without gamete production or fusion. In the process of budding in Hydra, a bud develops as an outgrowth due to repeated cell division of reproductive cells at one specific site. These buds develop into tiny individuals, and when fully mature, detach from the parent body as new independent individuals.

Question 28. What is regeneration? Give one example of an organism that shows this process and one organism that does not. Why does regeneration not occur in the latter? Answer: Regeneration is the ability of organisms to give rise to new individual organisms from their body partrs. Planaria show this process and Amoeba does not. Regeneration does not occur iş Amoeba because regeneration is carried out by specialised cells which are not present in non-regenerating organisms like Amoeba.

Question 29. Illustrate the following: (i) Spore formation in Rhizopus. (ii) Multiple fission in Plasmodium. Answer: (i) Spore formation in Rhizopus: This is an asexual method of reproduction in bacteria and fungi. Spores are unicellular bodies formed by cell division in a parent organism. After detaching from the parent, and if conditions are suitable, they germinate directly or indirectly into a new individual.

(ii) Multiple fission in Plasmodium: It is an asexual mode of reproduction in organisms. Here, the nucleus of the organism divides repeatedly to form a number of equal-sized daughter nuclei and each daughter nuclei breaks away together with a small portion of the cytoplasm.

Question 30. Illustrate the following with the help of suitable diagrams: Leaf of Bryophyllum with buds. Answer: Leaf of Bryophyllum shows vegetative propagation in plants where a part of the body becomes detached and develops into a new supporting plant. Here, leaves of Bryophyllum pinnatum having plantlets along the leaf margins when grown in soil develops into a new plant.

Question 33. In the context of reproduction of species state the main difference between fission and fragmentation. Also give one example of each. Answer: Fission is the method of asexual reproduction in unicellular forms of life. In this process the parent organism splits to form two or more daughter cells. Example, Amoeba and Plasmodium. Fragmentation is the process found in multicellular organisms. The filament breaks up into two or more pieces upon maturation. These pieces then grow into new individuals. Example, Spirogyra.

Question 35. What are the various methods of vegetative propagation? Discuss any one method with example. Answer: The various methods of vegetative propagation are:

• tissue culture.

Layering: In layering, roots are induced on the stem of a rooted plant. When roots develop, that part of stem is detached from the parent plant and grown in the soil. Layering is of two types:

(i) Mound layering: A lower branch of a rooted plant is bent and buried into the moist soil. The tip of the branch should remain above the ground. In a few days, the buried part of the branch develops roots. It is now cut off from the parent plant and grown in the soil as a new plant. This method is used in the propagation of grapevine, strawberry, raspberry, jasmine, etc.

(ii) Air layering: This method is used in plants like crotons whose branches cannot be bent and buried in the soil. The stem is girdled, i.e., a ring of bark is removed and then it is covered with a moist moss or cotton and enclosed in a polythene bag. After a few days, roots emerge from this region and branch is cut off from the parent plant. It can now be planted in the soil as a new plant. This method is used in rose, rubber plant, guavas, pear, apple, mangoes, etc.

Question 36. Explain the term ‘Regeneration’ as used in relation to reproduction of organisms. Describe briefly how regeneration is carried out in multicellular organisms like Hydra. Answer: Regeneration is the ability of an organism to give rise to a new organism or individual from their body parts. Each part of Hydra contains specialised cells which have the ability to proliferate.

When the body of Hydra by any means is cut into number of pieces, these pieces proliferate and make large number of cells. From this mass of cells, different cells undergo changes to become various cell types and tissues finally developing into a new organism.

Question 37. Explain four advantages of vegetative propagation. Answer:

• New plants produced by vegetative propagation maintain the desirable characters of the parents. These plants are genetically identical.
• Certain plants like banana, grapes, pineapple, roses, jasmine, etc., do not form seeds. Thus, this is the only method of reproduction and continuation of such species.
• This method is cheap and can be easily employed to reproduce plants, especially fruit plants.
• Only one parent is required for reproduction.

Question 38. Describe double fertilization in plants. Answer: Soon after pollination the pollen grains start germinating and form a pollen tube. The pollen tube grows within the style till it reaches the ovary.

On reaching the ovary it enters the ovule through an opening called micropyle. In the meantime, two male gametes are formed in the pollen tube. One of the male gametes fuses with the egg, the process is called syngamy. The product formed is termed as zygote. The other male gamete fuse with the two polar nuclei, one from each end of embryo sac, to form endosperm nucleus. This process is called triple fusion.

In this process three nuclei, two polar nuclei and one male gamete is involved, so it is called triple fusion. Thus, inside each embryo sac two fusions, i.e., syngamy and triple fusion take place. This mechanism of two fusions occuring in an embryonal sac is called double fertilisation. After fertilization, the ovule develops into seed and the ovary develops into a fruit.

Question 39. State the basic requirement for sexual reproduction ? Write the importance of such reproductions in nature. Answer: Formation of male and female gametes and fusion of gametes or syngamy is the basic requirement for sexual reproduciton. Importance: Combination of DNA from two different individuals lead to increase in genetic variation in the organism. This leads to diversity in the population which helps in natural selection.

Question 40. List any four steps involved in sexual reproduction and write its two advantages. Answer: Steps involved in sexual reproduction are as follows:

• Formation of male and female gametes.
• Transfer of male gamete to female gamete.
• Fusion of gametes resulting in zygote formaton.
• Zygote grows into an embryo forming a new individual.

Its advantages are:

• It increases genetic variation.
• It plays an important role in the origin of new species.
• It promotes diversity in the offsprings.

Question 41. Mention secondary sexual characters in human male and female. Answer: Secondary sexual characters in male:

• Hair growth on face, chest, armpit (axillae). and over pubis.
• Voice becomes deep and hoarse due to growth of larynx called Adam’s apple.
• Body becomes muscular.

Secondary sexual characters in female:

• Growth of breasts and hair in axillae and over pubis.
• Pelvis region becomes broad and buttocks become heavy due to deposition of fat.
• Development of accessory sex orgAnswer:

Question 42. (a) Mention the ole of the following organs of human male reproductive system: (i) Testis; (ii) Scrotum; (iii) Vas deferens; (iv) Prostate glands. (b) What are the two roles of testosterone ? Answer: (a) (i) Testis: To produce male gametes. (ii) Scrotum: To provide optimal temperature to tęstis for the formation of sperm. (iii) Vas deferens: To deliver the sperms to the urinary bladder. (iv) Prostrate glands: To secrete the fluid which provides nutrition and medium for transport of sperms.

(b) Testosterone has following roles: (i) It regulates the formation of sperms. (ii) It brings about the changes in boys during adolescence.

Question 43. Explain how, offspring and parents of organisms reproducing sexually have the same number of chromosomes. Or How do organisms, whether reproduced asexually or sexually maintain a constant chromosome number through several generations ? Explain with the help of suitable example. Answer: During asexual reproduction organisms undergo only mitotic divisions. The DNA (in the chromosomes) of the cells involved are copied and then equally divided among the two daughter cells formed. Thus, chromosome number remains unchanged.

In sexual reproduction, organisms produce gametes through meiosis, which is called reductional division, in which the original number of chromosomes becomes half. These two gametes combine to form the zygote and the original number of chromosomes is restored.

For example, in humans, the parents (father and mother) each have 46 or, 23 pairs of chromosomes. In the gametes, the sperm has half the number of chromosomes, i.e., 23 and the egg also has 23 chromosomes. When the sperm and the egg fuse, the zygote has 46 or 23 pairs of chromosomes. .

Thus, the chromosome number remains constant.

Question 44. What are the male and female gonads in human beings ? Mention their functions. Answer: The male gonads in human beings are a pair of testes. The testis lies in a sac outside the abdominal cavity called scrotum. The function of testis.is to regulate the production of sperms and secretion of male hromone, testosterone. The female gonads in human beings are pair of ovaries located in the abdominal cavity near the kidneys. The ovaries perform dual functions of production of female hormones-oestrogen and progesterone and the production of female gamete (ovum/ova).

Question 45. Name the two types of mammalian gametes. How are these different from each other ? Name the type of reproduction they are involved in. Write the advantage of this type of reproduction. Answer: Two types of mammalian gametes are sperm and ovum or egg. . Sperms are motile and are produced by male individuals whereas ova or eggs are non-motile and produced by female individuals. They are involved in sexual reproduction. Advantage: Sexual reproduction generates more variations among organisms.

Question 46. From the internet, gather information about the chromosome numbers of five animals and five plants. Correlate the number with the size of organism and answer the following questions: (i) Do larger organisms have more number of chromosomes/cells ? (ii) Can organisms with fewer chromosomes reproduce more easily than organisms with more number of chromosomes ? (iii) More the number of chromosomes/cells greater in the DNA content. Justify. Answer:

• No, there is no relationship between size of organism and its chromosome number.
• No, process of reproduction follows a common pattern and is not dependent on the number of chromosomes.
• Yes, since the major component of chromosome is DNA, if there are more chromosomes in a cell, the quantity of DNA will also be more.

Question 47. What happens when:

• Planaria gets cut into two pieces?
• a mature Sporogyra filament attains considerable length ?
• on maturation sporangia burst?
• Each piece regenerates into a new Planaria.
• Its filaments break into smaller pieces or fragments and each fragment gives rise to a new filament.
• It releases spores which germinate into new mycelium in moist conditions.

Question 48. What happens when:

• accidently, Planaria gets cut into many pieces ?
• Bryophyllum leaf falls on the wet soil ?
• on maturation sporangia of Rhizopus bursts?
• On getting cut into many pieces, each piece regenerates into new Planaria.
• When leaf falls on the wet soil, buds are produced in leaf notches and develop into new plants.

Question 49. Mention the information source for making proteins in the cell. What is the basic event in reproduction? Answer: The DNA in the nucleus of a cell is the information source for making protiens. If the. information is changed, different protiens will be made. The basic even in reproduction is the creation of a DNA copy. Cells use chemical reactions to build copies of their DNĀ. This creats two copies of the DNA in a reproducing cell and they need to get separated from each other. DNA copying is accompanied by the creation of an additional cellular apparatus, and then the DNA copies separate, each with its own cellular apparatus.

Question 50. (i) Write the names of those parts of a flower which serve the same function as the following do in the animals: (a) Testis (b) Sperm (c) Ovary (d) Egg (ii) State the function of flowers in the flowering plants: Answer: (i) (a) Testis – anther (b) Sperm – pollen grains (c) Ovary – ovary (d) Egg – ovum

(ii) Flowers are responsible for sexual reproduction as they contain the reproductive organs of the plant.

Question 51. What are sexually transmitted diseases? List two examples of each disease caused due to: (i) bacterial infection (ii) viral infection. Which device or devices may be used to prevent the spread of such diseases? Answer: Diseases which are transmitted from an infected person to a healthy person due to unsafe sex are called sexually transmitted diseases.

Two examples: Bacterial diseases: Gonorrhoea and syphilis i Viral diseases: Warts and AIDS Preventive measures: Use of condoms or similar coverings.

Question 52. (i) Name any two sexually transmitted diseases (STDs). How do these infectious diseases spread from one person to another? Give two symptoms of STDs. (ii) Explain why fertilisation is possible if copulation takes place during the middle of menstrual cycle. Answer: (i) The two sexually transmitted diseases (STDs) are gonorrhoea and syphilis. These infectious diseases spread from one person to another by sexual contact with an infected person. Two symptoms of STDs are burning sensation at urination and urethral discharge and sores in the genitals. (ii) Since ovulation, i.e., the release of ovum occurs on the 14th day of the menstrual cycle i.e., in its middle, chances are more for the sperms to fertilise the egg or oyum during this time:

Question 53. Write the full form of IUCD, AIDS, HIV, OC. Answer:

• IUCD = Intra-Utreine-Contraceptive Device
• AIDS = Acquired Immune Deficiency Syndrome
• HIV = Human Immunodeficiency Virus
• OC = Oral Contraceptive.

Question 55. What is placenta ? Mention its role during pregnancy. or What is placenta ? Explain its function in humAnswer: Answer: Placenta is a special tissue connection between embryo and uterine wall. It acts as an endocrine gland. Role of placenta:

• It possesses villi that increase the surface area for absorption of nutrients.
• It facilitates the passage of nutrition and oxygen to embryo from mother through blood.
• Waste substances produced by embryo are removed through placenta into mother’s blood.

Question 58. What are the functions of testis in the human male reproductive system ? Why are these located outside the abdominal cavity ? Who is responsible for bringing about changes in appearance seen in boys at the time of puberty ? Answer: Functions of testis:

• Production of sperms,
• Production of male hormone/testosterone.

These are located outside the human body, as sperms needs lower temperature than the normal body temperature. Testosterone is responsible for bringing changes at the time of puberty in boys.

Question 59. What is contraception ? Name any two methods. How does the use of these methods have a direct effect on the health and prosperity of a family? State any three points. Answer: Any method which prevents conception or pregnancy is called contraception. . Barrier method, chemical method and surgical method are the different contraceptive methods. Use of these methods have direct effect on the health and prosper ty of a family because:

• Health of women (mother) is maintained.
• Parents can give more attention to their children.
• More resources may be made available for improvement of standard of living.

Question 60. What are the permanent methods of family planning ? Write short notes on any two. Answer: Surgical methods are also called permanent method of family planning. Surgical meth ods are of two types: (i) Vasectomy: Small portion of the sperm duct is cut or tied properly. Therefore the sperm transfer will be prevented. (ii) Tubectomy: Small portion of oviduct is cut or tied properly. The fallopian tube in the female gets blocked.

How do Organisms Reproduce Extra Questions Long Answer Type

Question 2. What is multiple fission? How does it occur in an organism? Explain briefly. Name one organism which exhibits this type of reproduction. Answer: Multiple fission is the process of reproduction in which many daughter individuals are formed or produced from the parent cell. In this process, the nucleus divides repeatedly to produce large number of nuclei. Each nucleus gathers a bit of cytoplasm around itself and develops a membrane around each structure. Many daughter cells develop which on liberation grow into adult organisms. Plasmodium exhibits multiple of fission.

Question 3. (i) Describe asexual reproduction in Amoeba. (ii) How does sexual reproduction in plants takes place? Answer: (i) In Amoeba, asexual reproduction occurs by fission (binary and multiple). In Amoeba, nucleus first divides into two daughter nuclei by mitosis and then body along with the cytoplasm constricts from the middle, which gradually deepens and eventually divides into two individual parts, each part has one nucleus. Thus, two daughter Amoeba develop from one. This is called binary fission.

• The male reproductive organ ‘stamen’ makes the male gametes.
• The female reproductive organ ‘carpel’ makes the female gametes.
• The male gametes fertilise the female gametes.
• The fertilised ovules grow and become seeds.
• The seeds produce new plants under favourable conditions like presence of water warmth, air, light, etc.

The other male gamete fuses with two polar nuclei one from each end of embryo sac to form Ovary endosperm nucleus. This fusion is called triple fusion. The zygote grows into an embryo and an endosperm nucleus grows into endosperm (the food storage tissue of seed).

(ii) Sperms are produced much more in number than eggs because: (a) Eggs are non-motile whereas sperms are motile and they may be misdirected while they are travelling towards eggs. (b) Sperms may not be able to survive under external environmental conditions for long. (c) To increase the probability of fertilisation of eggs.

Question 5. Give one example each of unisexual and bisexual flowers. Differentiate between the two types of pollination that occur in flowers. What happens when a pollen lands on a suitable stigma ? Write about the events that occur till the seed formation in the ovary. Answer: Unisexual Flower: papaya, watermelon Bisexual Flower: hibiscus, rose The two types of pollination are self pollination and cross pollination. Self pollination: The pollen grains are transferred from the anther to the stigma of the same flower or to the flower of the same plant. Cross pollination: The pollen grains are transferred from the anther to the stigma of a flower of a different plant.

The following events takes place:

• After pollen lands on a suitable stigma, a pollen tube grows out of pollen grain and travels through the style to reach the ovary.
• The male germ cell fuses with the female germ cell to form a zygote.
• The zygote divides several times to form an embryo within the ovule.
• The ovule develops tough coat and gradually gets converted into a seed.

Question 6. (i) State in brief the functions of the following organs in the human female reproductive system: Ovary, Fallopian tube, Uterus (ii) What is menstruation ? Why does it occur? Answer: (i) Functions of ovary are:

• Production of female gamete.
• Production of female harmone.

Functions of fallopian tube are:

• It is the site of fertilisation.
• Transfer of female gamete from ovary takes place through it.

Functions of uterus are:

• Implantation of zygote.
• Nourishment of developing embryo.

(ii) Menstruation: It is the periodic breakdown of uterine lining and its removal along with blood and mucous in (post pubertal stage of a) human female.

Uterine lining is required to nourish the embryo that is formed if fertilisation takes place. In absence of fertilisation, the lining is not required and hence it sheds in the form of mensuration.

Question 7. Write the functions of the following in human female reproductive system: Ovary, oviduct, uterus How does the embryo get nourishment inside the mother’s body ? Explain in brief. Or (i) Write the functions of the following parts in human female reproductive system: (a) Ovary (b) Oviduct (c) Uterus (ii) Describe the structure and functions of placenta. Or List two functions of ovary of human female reproductive system. Answer: Ovary:

• Production of female hormone (Oestrogen and progesterone).
• Production of female gamete or egg.
• Transfer of female gamete from the ovary
• Site of fertilisation.
• Implantation of zygote or embryo.
• The embryo inside the mother’s body gets nourishment through the placenta.

The placenta is a special disc-like tissue embedded in the mother’s uterine wall and connected to the embryo. Placenta provides a large surface area for glucose and oxygen, and nutrients to pass from the mother’s blood to the embryo.

Question 8. (i) Name the human male reproductive organ that produces sperms and also secretes a hormone. Write the functions of the secreted hormone. (ii) Name the parts of the human female reproductive system where (a) fertilisation takes place (b) implantation of the fertilised egg occurs. (iii) Explain how the embryo gets nourishment inside the mother’s body. Or (i) Name the organ that produces sperms as well as secretes a hormone in human males. Name the hormone it secretes and write its functions. (ii) Name the parts of the human female reproductive system where fertilization occurs. (iii) Explain how the developing embryo gets nourishment inside the mother’s body. Answer: (i) Testes produce sperms and secrete a hormone called testosterone. The function of testosterone is to control the development of male sex organs and secondary sexual features. (ii) (a) Oviduct or fallopian tubes (b) Uterus (iii) After implanation, a disc-like special tissue called placenta develops between the uterus wall and the embryo which helps in the exchange of nutrients, oxygen and waste products between the embryo and the mother.

Question 9. Reproduction is essentially a phenomenon that is not for survival of an individual but for the stability of a species. Justify. Answer: (a) Organisms need energy for survival which they obtain from life processes such as nutrition and respiration. (b) Reproduction needs a lot of energy. (c) Genetic material is transferred from one generation to the next as a result of reproduction through DNA copying. (d) DNA copying takes place with high constancy and considerable variations, that is, advantageous to the species for stability in the changing environment.

NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12

MCQ Questions for Class 10 Science How do Organisms Reproduce? with Answers

October 22, 2019 by Veerendra

Free PDF Download of CBSE Class 10 Science Chapter 8 How do Organisms Reproduce? Multiple Choice Questions with Answers. MCQ Questions for Class 10 Science with Answers was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 10 Science How do Organisms Reproduce? Multiple Choice Questions with Answers to know their preparation level.

Class 10 Science MCQs Chapter 8 How do Organisms Reproduce?

1. During favourable conditions, Amoeba reproduces by (a) multiple fission (b) binary fission (c) budding (d) fragmentation

2. A feature of reproduction that is common to Amoeba, Yeast and Spirogyra is that (a) they reproduce asexually (b) they are all unicellular (c) they reproduce only sexually (d) they are all multicellular

3. The ability of a cell to divide into several cells during reproduction in Plasmodium is called (a) budding (b) multiple fission (c) binary fission (d) reduction division

4. Bryophyllum can be propagated vegetatively by the (a) stem (b) leaf (c) root (d) flower

5. Vegetative propagation refers to formation of new plants from (a) stem, flowers and fruits (b) stem, leaves and flowers (c) stem, roots and flowers (d) stem, roots and leaves

6. In a potato, vegetative propagation takes place by: (a) root (b) leaf (c) stem tuber (d) grafting

7. Vegetatively propagated plants (a) do not bear roots (b) do not bear buds (c) are genetically similar (d) are genetically dissimilar

8. Spirogyra reproduce by (a) budding (b) fragmentation (c) regeneration (d) fission

9. In Rhizopus, tubular thread like structures bearing sporangia at their tips are called (a) filaments (b) hyphae (c) rhizoids (d) roots

10. Plants like banana, rose, jasmine, orange have lost the capacity to produce (a) seeds (b) buds (c) flower (d) roots

11. The flower of the Hibiscus plant is (a) bisexual (b) unisexual (c) neuter (d) very small

12. The part of the flower which is present in the centre of the flower is (a) Sepals (b) Petals (c) Carpels (d) Stamens

13. The seed that contains the future plant is called the (a) cotyledons (b) seed coat (c) germ cells (d) embryo

14. The period of pregnancy is called (a) gestation period (b) incubation period (c) ovulation (d) menstruation period

15. The process of release of eggs from the ovary is called (a) menstruation (b) reproduction (c) insemination (d) ovulation

16. The period during adolescence when the reproductive tissues begin to mature is called (a) ovyfetion (b) puberty (c) germination (d) propagation

17. In human beings, the fertilization occurs in the (a) uterus (b) ovaries (c) fallopian tubes (d) vagina

18. Along the path of the vas-deferens the secretions of which gland provide nutrition to the sperms? (a) Prostate glands (b) Seminal vesicles (c) Scrotum (d) Urinary bladder

19. The embryo in humans gets nutrition from the mother’s blood with the help of a special tissue called (a) Placenta (b) Villi (c) Uterus (d) Womb

20. Which among the following diseases is not sexually transmitted? (a) Syphyllis (b) Hepatitis (c) HIV-AIDS (d) Gonorrhea

21. Which of the following method of contraception protects from acquiring sexually trans¬mitted diseases? (a) Surgery (b) Condoms (c) Copper-T (d) Oral-pills

22. In human males, the testes lie in the scrotum, because it helps in the (a) process of mating (b) formation of sperms (c) easy transfer of gametes (d) secretion of estrogen

Fill in the Blanks

1. The process of reproduction involving only one cell or one parent is called ………….. . 2. ………….. is a duct coming from the urinary bladder which carries sperms. 3. Process of fertilization takes place in the ………….. tube in humans. 4. ………….. is the ability of an organism to replace its lost body parts. 5. ………….. is called the production of new plants from stems, roots or leaves. 6. ………….. is the term used to refer to the commencement of menstruation at puberty. 7. ………….. is the virus that causes AIDS.

1. Uniparental/ Asexual reproduction 2. Vas deferens 3. fallopian 4. Regeneration 5. Vegetative propagation 6. Menarch 7. HIV-Human Immuno Virus

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