critical thinking questions on seed germination

1. Where/how to store seeds for flowers and vegetables ?

Seeds retain their viability when stored at cool temperatures, lower humidity and reduced light exposure. Begin by harvesting high-quality seeds from healthy produce. Next, be sure to thoroughly dry the seeds, then seal them in an airtight container . A jar or zippered plastic bag works well. Next, place the sealed container in the refrigerator or freeze them for storage. Be sure to label the seeds to avoid mix-ups in the spring. It's advisable to use seeds as soon as possible for the quickest germination rate.

2. How long do seeds stay fresh ?

How long seeds stay fresh depends upon the type of seed and how the seeds were stored. Seeds stored in a cool, dry, dark location will remain fresher for a longer period of time. On average, most types of vegetable seeds will be viable for 2 to 3 years. Lettuce seed is particularly long-lived and can last for up to 5 years. On the other hand, parsnips rarely germinate after 1 year. To determine freshness, conduct a germination test on the seeds by placing 10 seeds on a moist paper towel. Seal the paper towel in a plastic bag or container. Wait ten days and count the number of seeds which sprouted.

3. Why are some of my seedlings tall and flopping over ?

Legginess in seedlings is a symptom of inadequate exposure to light. This condition causes seedlings to grow tall and narrow stems which can't support the weight of the leaves. Most vegetable plants require 6 to 8 hours of direct sunlight per day. When sowing outdoors, plant vegetable seeds in a sunny location. Artificial lighting is often necessary when starting seedlings indoors. Florescent tubes were a popular choice in the past, but have since been phased out. These are being replaced with LED bulbs. Most indoor seedlings require 16 hours of artificial light per day to prevent legginess.

4. Can you still plant frozen seeds ?

Yes! In northern climates, seeds from native plants frequently lay in frozen ground before germinating as soil temperatures rise in the spring. In fact, seeds of some species require a cold period, or stratification , before germination can proceed. Additionally, seed banks freeze their seeds in order to preserve and extend their freshness. To freeze seeds, be sure they are thoroughly dry as moisture can cause the seed to crack as it freezes. Place the seeds in an airtight container and avoid exposing frozen seeds to bursts of warm, humid air. Keep the frozen seeds at a constant temperature until they are thawed for planting.

5. What seeds should be soaked and why ?

Soaking seeds is a gardening trick to speed up germination rates. Larger seeds, those with a tough seed coat or ones which are traditionally slow to germinate, will benefit the most from soaking. Soaking seed is also useful whenever faster germination is desirable. To soak seeds, place them in a bowl of warm water. Large seeds, such as peas and beans, require an overnight soak of 8 to 10 hours. Smaller or thin-walled seeds can benefit from soaking for as little as 1 to 2 hours.

6. Do all seeds need to be covered in order to germinate ?

Covering seedlings is not necessary but it helps retain moisture levels which is essential for completion of the germination process. If seeds dry out at critical times, they may fail to sprout. If a cover is not used, it's advisable to regularly check the seeds and mist with water to maintain a moist medium. Some seeds also require light to germinate, so any cover should be 100% transparent. Many seed starting trays come with clear covers, but these often get lost or damaged over the years. Plastic wrap can be used a substitute to cover seed cells. To prevent fungal disease and rotting, be sure to remove any covering once the seeds have sprouted.

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7. What does it mean when it says to "sow thinly" ?

Instructions to " sow thinly " often accompanies packets containing very small seeds. The challenge with sowing small seeds is getting them spaced far enough apart to prevent overcrowding once the seeds germinate. Trying to thin overcrowded seedlings can result in root damage and lost plants. To thinly sow seeds, space small seeds 3/16 to Â½ inch (5 to 10 mm.) apart. Using a seed syringe or mixing the seeds with fine sand can make this task easier.

8. What are the brown discs used for growing seeds ?

Seed-starting discs are used for germinating seeds, growing seedlings and in hydroponic gardening. Coir discs are manufactured using the husk or shell of coconuts and are considered eco-friendlier than those made with peat. To use seed-starting discs, soak them in warm water until they are fully expanded. The top of the disc contains an indent or small hole in the material covering the discs. Use this hole to insert the seeds. Keep the discs moist and warm while the seeds germinate. Once seedlings have 2 to 3 sets of true leaves, the disc and seedling can be planted into a pot, transplanted directly into the garden or placed into the growing chamber of a hydroponic system.

9. What is the best type of clay for making seed balls ?

Credited as being a "whole habitat in a tiny clay ball," seed balls are an easy way to distribute seeds in hard-to-sow areas. They contain seeds, humus and clay. Making seed balls is fairly easy (and a fun project with kids): Mix the clay and humus with enough water to give the consistency of modeling clay. Knead in the seeds and roll the mixture into 1-inch (2.5 cm.) balls. For the best results, use pottery clay. Look for it at your local craft or art supply store.

10. How many seeds do you put in each hole or pot ?

The generic answer is 2 to 3 seeds per hole. This ensures each pot will sprout a seedling. Once the seedlings have developed true leaves, choose the strongest plant in each pot and cull any "extra" seedlings by cutting them off at ground level. This eliminates competition and gives the stronger plants room to grow. However, different species have different seed germination rates. When planting large numbers of the same seed, conduct a germination test and adjust the number of seeds per hole to better reflect the germination rate.

We all have questions now and then, whether long-time gardeners or those just starting out. So if you have a gardening question, get a gardening answer . We're always here to help.

Laura Miller has been gardening all her life. Holding a degree in Biology, Nutrition, and Agriculture, Laura's area of expertise is vegetables, herbs, and all things edible. She lives in Ohio.

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Critical Thinking Questions

Shallow roots do not anchor the plant to the ground and can be easily uprooted. Once the plant is no longer in the ground, the roots are unable to grow back.
Plants with shallow roots do not anchor the plant to the ground; meristems can be easily damaged and cannot grow back when not in the ground.
Shallow roots do not anchor the plant to the ground and can be easily uprooted. Once the plant is no longer in the ground, roots take a long time to grow back.
Shallow roots anchor the plant to the ground strongly but can be easily uprooted, and they grow back very slowly.
dermal tissue
meristematic tissue
vascular tissue
ground tissue

How do the locations and the functions of the three types of meristematic tissues compare?

Apical meristems found in the tip of stems and roots promote growth by elongation; lateral meristems found at nodes and bases of leaf blades promote increase in length; and intercalary meristems found in the vascular and cork cambia promote increase in girth.
Apical meristems found at nodes and bases of leaf blades promote growth by elongation; lateral meristems found in the vascular and cork cambia promote increase in girth; and intercalary meristems found in the tip of stems and roots promote increase in length.
Apical meristems found in the tip of stems and roots promote growth by elongation; lateral meristems found in the vascular and cork cambia promote increase in girth; and intercalary meristems found at nodes and bases of leaf blades promote increase in length.
Apical meristems found in the tip of stems and roots promote growth by elongation; lateral meristems found in the vascular and cork cambia promote increase in length; and intercalary meristems found at nodes and bases of leaf blades promote increase in length.

In an experiment on transport in plants, seedlings are exposed to radiolabeled minerals. In a second experiment, plants are provided with CO 2 that is labeled with 14 C. At the end of each experiment, tissue slices are analyzed for the presence of radiolabeled minerals and radioactive sucrose. Which plant tissue would show the presence of labeled minerals and which would show the presence of radioactive sucrose?

Phloem tissue would show the presence of labeled minerals, and xylem tissue would show the presence of radioactive sucrose.
Xylem tissue would show the presence of labeled minerals, and phloem tissue would show the presence of radioactive sucrose.
Parenchyma would show the presence of labeled minerals, and sclerenchyma would show the presence of radioactive sucrose.
Sclerenchyma would show the presence of labeled minerals, and parenchyma would show the presence of radioactive sucrose.
Simple tissue is made of cells that have different shapes, so the specimen will show oval, polygonal, and other shapes.
Simple tissue is made of cells that have intercellular spaces, so the specimen will contain spaces.
Simple tissue is made of cells that are elongated and tapered, so the specimen will show elongated cells.
Simple tissue is made of cells that are morphologically similar, so the specimen will appear uniform.
It anchors the plant, so that it is not easily uprooted by predators or wind. It is a sink for proteins that is protected from herbivores by being underground.
It anchors the plant, so that it is not easily uprooted by predators or wind. It is a source of starches that is protected from herbivores by being underground.
It anchors the plant, so that it cannot be uprooted by predators or wind. It is a sink for starches that is protected from herbivores by being underground.
It anchors the plant, so that it is not easily uprooted by predators or wind. It is a sink for starches that is protected from herbivores by being underground.
In monocots, the vascular bundles form a distinct ring. In dicots, the vascular bundles are scattered in the ground tissue.
In monocots, the vascular tissue forms a characteristic X shape in the center. In dicots, the phloem and xylem cells are scattered in the pith.
In monocots, the vascular bundles are scattered in the ground tissue. In dicots the vascular bundles form a distinct ring.
In monocot roots, the pith is absent or very small. In dicots, the pith is large and well developed.

What are the functions of stomata and guard cells, and what would happen to a plant if these cells did not function correctly?

Guard cells allow carbon dioxide to enter and exit the plant. Stomata regulate the opening and closing of guard cells. If the cells didn’t function, photosynthesis and transpiration would cease, which would interfere with the necessary continuous flow of water upward from roots to leaves.
Stomata allow oxygen to enter and exit the plant. Guard cells regulate the opening and closing of stomata. If the cells didn’t function, photosynthesis would continue but transpiration would cease, which would interfere with the necessary continuous flow of water upward from roots to leaves.
Guard cells allow carbon dioxide to enter and exit the plant. Stomata regulate the opening and closing of guard cells. Transpiration and in turn, photosynthesis would not occur, which is necessary to maintain a continuous flow of water upwards from the roots to the leaves.
Stomata allow gases to enter and exit the plant. Guard cells regulate the opening and closing of stomata. Photosynthesis and, in turn, transpiration, would not occur, which is necessary to maintain a continuous flow of water upwards from the roots to the leaves.
Cork will not be produced and the plant will not increase in girth.
Excess cork will be produced and annual rings will not be formed.
Cork will not be produced and the plant will not be able to exchange gases.
Excess cork will be produced and the plant will not increase in girth.
Annual rings can also indicate the height of the tree.
Annual rings can also indicate the climatic conditions that prevailed during each growing season.
Annual rings can also indicate in which season the tree was sown.
Annual rings can also give an estimation of how long a particular tree is going to live.

Modified stems give an advantage to plants. What advantage do rhizomes, stolons, and runners provide? What advantages do corms, tubers, and bulbs provide?

Rhizomes, stolons, and runners give rise to new plants that are the clones of the parents and they store food. Corms, tubers, and bulbs can also produce new plants.
Rhizomes, stolons, and runners give rise to new plants that are the different from the parents. Corms, tubers, and bulbs can also produce new plants as well as store food.
Rhizomes, stolons, and runners give rise to new plants that are the clones of the parents. Corms, tubers, and bulbs can also produce new plants as well as store food.
Rhizomes, stolons, and runners give rise to new plants that are similar to the parents but show genetic variability. Corms, tubers, and bulbs can also produce new plants as well as store food.
The vascular bundles join to form growth rings.
The vascular bundles divide into primary xylem and primary phloem.
The vascular bundles divide into secondary xylem and primary phloem.
The vascular bundles die out.

Which description correctly compares a tap root system with a fibrous root system?

A tap root system, such as that of carrots, has a single main root that grows down. A fibrous root system, such as that of wheat, forms a dense network of roots that is closer to the soil surface. Fibrous root systems are found in monocots, and tap root systems are found in dicots.
A fibrous root system, such as that of a carrot, has a single main root that grows down. A taproot system, such as that of wheat, forms a dense network of roots that is closer to the soil surface. Fibrous root systems are found in monocots, and tap root systems are found in dicots.
A taproot system, such as that of rice, has a single main root that grows down. A fibrous root system, such as that of a carrot, forms a dense network of roots that is closer to the soil surface. Fibrous root systems are found in monocots, and tap root systems are found in dicots.
A taproot system, such as that of a carrot, has a single main root that grows down. A fibrous root system, such as that of wheat, forms a dense network of roots that is closer to the soil surface. Taproot systems are found in monocots, and fibrous root systems are found in dicots.
It provides protection and helps in absorption.
It increases the surface area of root for absorption of water and minerals.
It protects meristem against injury and provides lubrication for the growing root to dig through soil.
It protects the meristem against injury and helps in absorption.
Water and minerals must follow entirely a path between cells, where selectivity occurs.
Water and minerals must follow entirely a path between cells, where no selectivity occurs.
Water and minerals must cross the endodermis.
Water and minerals must cross the tracheids of the xylem.
Food reserves are more nutritious underground. The soil conditions make these food reserves abundant.
Food reserves underground are hidden from potential predators. The soil conditions make these food reserves abundant.
Food reserves are more nutritious underground. The soil conditions such as moisture and temperature are less variable.
Food reserves underground are hidden from potential predators. Soil conditions such as moisture and temperature are less variable.

Some desert plants have taproots that extend up to 20–30 feet underground. Others have fibrous root systems that cover wide areas. What are the advantages of a deep taproot and the advantages of a fibrous root system in a desert?

A deep taproot can reach the deeper soil regions that stay moist after several rainfalls. A shallow fibrous system provides additional support to anchor the plant in the desert.
A deep taproot provides additional support to anchor the plant in the desert. A shallow fibrous system increases the amount of water that can be absorbed after a light rainfall when the soil dries quickly in the desert.
A deep taproot increases the amount of water that can be absorbed after a light rainfall when the soil dries quickly in the desert. A shallow fibrous system can reach the deeper soil regions that stay moist after several rainfalls.
A deep taproot can reach the deeper soil regions that stay moist after several rainfalls. A shallow fibrous system increases the amount of water that can be absorbed after a light rainfall when the soil dries quickly in the desert.

Samples of leaves from monocots and dicots are piled on the table in a laboratory and students are sorting the leaves. What information will help them know which leaves to identify as monocots?

Cork cambium cells are usually absent from monocots, whereas they are present on the upper epidermis of dicot leaves.
Monocots have leaves with parallel venation, and dicot leaves have reticulate, net-like venation.
Bilateral symmetry is observed in monocot leaves, whereas isobilateral symmetry is observed in dicot leaves.
Monocots have leaves with reticulate, net-like venation, and dicot leaves have parallel venation.
Compound leaves produce certain types of chemical compounds that are harmful to herbivores.
It is more efficient for large herbivores to eat large, simple leaves.
Compound leaves are thicker than simple leaves.
It is more efficient for large herbivores to eat the small leaflets of compound leaves.

Stomata are usually found in higher numbers on the abaxial or bottom surface of a leaf. What is the advantage of such an arrangement?

Presence of stomata on the abaxial or bottom surface ensures that no, or very little, water is lost due to guttation.
The abaxial or bottom surface receives more sunlight, and water evaporates faster by transpiration.
Herbivores do not prefer to eat leaves with stomata on the abaxial or bottom surface.
The adaxial or upper surface receives more sunlight, and water evaporates faster by transpiration.
Conifers such as spruce, fir, and pine have oval-shaped leaves with sunken stomata, helping to reduce water loss.
Succulents such as aloes and agaves have waxy cuticles with sunken stomata, helping to reduce water loss.
Conifers such as spruce, orchids, and pine have needle-shaped leaves with sunken stomata, helping to reduce water loss.
Conifers such as spruce, fir, and pine have needle-shaped leaves with sunken stomata, helping to reduce water loss.

How is a leaf different from a leaflet?

A leaf petiole attaches directly to the stem at a bud node, whereas a leaflet petiole is attached to the main petiole or the midrib, not the stem.
A leaf has reticulate venation, whereas leaflets show parallel venation.
A leaf petiole attaches to the main petiole or the midrib, not the stem, whereas a leaflet petiole attaches directly to the stem at a bud node.
A leaf has parallel venation, whereas leaflets show reticulate venation.

Scientists on a new project to restore a damaged salt marsh are investigating several plants that could be introduced. Plant X is considered a possible candidate. Before the decision is made, the following data are examined. Assume that the contribution of gravity and matric potential are negligible and can be ignored. Recall that the overall water potential for a system is represented by the equation Ψsystem = Ψtotal = Ψs + Ψp + Ψg + Ψm;

overall Ψ of the soil is -2.1MPa, the solute potential of the plant’s cell contents is -0.12MPa, and the pressure potential (Ψp) of the plant’s cells and -2.3 MPa

Is Plant X a good candidate for introduction to the salt marsh?

Yes, because the overall water potential of the plant is less negative than the water potential of the soil.
No, because the overall water potential of the plant is less negative than the water potential of the soil.
Yes, because the overall water potential of the plant is more negative than the water potential of the soil.
No, because the overall water potential of the plant is more negative than the water potential of the soil.

When organisms transitioned to land, they developed different mechanisms to provide water to their cells and tissues. How are plant adaptations to land different from mammalian adaptations to land with respect to the mechanisms by which they obtained water for their cells?

Programmed cell death or apoptosis occurs in plant development in tissues such as xylem. It also is an important process in animal development. How do you suppose apoptosis contributes to the development of hands in humans?

The paint clogged the stomata. Without photosynthesis, the plant could not pull water from the soil.
The paint clogged the stomata. Without transpiration, the plant could not pull water from the soil.
The paint clogged the hydathodes. Without transpiration, the plant could not pull water from the soil.
The paint clogged the stomata. Without guttation, the plant could not pull water from the soil.
Movement of water up the xylem and movement of solutes up and down the phloem
Movement of water up the phloem and movement of solutes up and down the xylem.
Movement of water up and down the xylem and movement of solutes up the phloem
Movement of solutes up the xylem and movement of water up and down the phloem

During a severe drought, the soil becomes dry and its water potential decreases. Many plants will wilt in such an environment. Consider that the overall water potential for a system is represented by the equation Ψsystem = Ψtotal = Ψs+ Ψp + Ψg + Ψm. What is one reason that plants are unable to draw water from the soil?

The water potential of the soil becomes lower than the water potential of the plants.
The water potential of the soil becomes lower than the solute potential of the plants.
The water potential of the soil becomes higher than the water potential of the plants.
The solute potential of the soil becomes lower than the water potential of the plants.

A botanist compares the number of stomata between two plants. One plant, a eucalyptus, has stomata equally distributed on both sides of the leaf. The other plant has most of its stomata on the underside of the leaf. What does the positioning of the stomata indicate about which leaf surfaces on the two plants receive light in their natural environment?

The first plant receives light only on the upper surface of the leaves, whereas the leaves of the second plant are equally exposed to sunlight.
The first plant receives light only on the lower surface, whereas the second plant receives light only on the upper surface.
The first plant receives light only on the upper surface, whereas the second plant receives light only on the lower surface.
The first plant has leaves that are equally exposed to sunlight, whereas the second plant receives light only on the upper surface.

In the Northern Hemisphere, owners and managers of plant nurseries have to plan lighting schedules for a long-day plant that will flower in February. What lighting periods and color will be most effective?

long periods of illumination with light enriched in the red range of the spectrum
short periods of illumination with light enriched in the red range of the spectrum
long periods of illumination with light enriched in the far-red range of the spectrum
short periods of illumination with light enriched in the far-red range of the spectrum
Without gravitropism, both roots and seedlings would grow upward.
Without gravitropism, roots would grow in all directions and seedlings would grow upward.
Without gravitropism, roots would grow upward but seedlings would not grow upward toward the surface.
Without gravitropism, roots would grow in all directions but seedlings would not grow upward toward the surface.
Refrigeration slows chemical reactions, including fruit ripening. Ventilation adds the ethylene gas that speeds up fruit maturation.
Refrigeration slows chemical reactions, including fruit maturation. Ventilation removes the ethylene gas that reduces fruit ripening.
Refrigeration slows chemical reactions, including fruit maturation. Ventilation removes the ethylene gas that speeds up fruit ripening.
Refrigeration removes the ethylene gas that speeds up fruit ripening. Ventilation slows chemical reactions, including fruit maturation.
Hair-like appendages on the surface of the leaves respond to repeated contact.
Hair-like appendages on the surface of the leaves respond to a single contact.
Hair-like appendages on the surface of the leaves respond to chemical stimulus from the insect.
Hair-like appendages on the surface of the leaves respond to the electrical stimulus from the insect.

Stomata close in response to bacterial infection. This response is a defense mechanism because it ________, and the hormone involved is ________.

restricts the entry of O 2 ; gibberellin
restricts the entry of CO 2 ; abscisic acid
prevents further entry of pathogens; auxin
prevents further entry of pathogens; abscisic acid
A seedling growing in the shade of a mature plant will not have enough light to promote meristematic growth. A seed with large storage will be able to sustain growth until its seedling can reach enough light for photosynthesis.
A seedling growing in the shade of a mature plant will not have enough light to promote photosynthesis. Small seeds with limited reserve will be able to sustain growth until seedlings can reach enough light for photosynthesis.
A seedling growing in the shade of a mature plant will not have enough light to promote photosynthesis. A seed with large storage will be able to sustain growth until its seedling can reach enough light for photosynthesis.
A seedling growing in the shade of a mature plant will not have enough light to promote respiration. Small seeds with limited reserve will be able to sustain growth until their seedlings can reach enough light for photosynthesis.

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