Seeds — Structure and Germination - Questions & Answers

1. Mention whether the following statements are True (T) or False (F)

(i) Plumule is the future root and radicle is the future shoot of the plant.
Answer: False

(ii) Micropyle serves for the emergence of the radicle.
Answer: False

(iii) Cotyledons in castor are a big store of food for the embryo.
Answer: False

(iv) Maize grain has a large endosperm.
Answer: True

(v) Tegmen is the outermost layer of the seed.
Answer: False

1. Fill in the blanks by choosing the correct alternative

(i) In a dry seed, the embryo is in quiescent state. (active/quiescent)

(ii) Water is absorbed by the seed mainly through micropyle. (entire surface/micropyle)

(iii) Very low temperature inhibits the growth of embryo. (inhibits/destroys)

(iv) Germination in pea is hypogeal. (epigeal/hypogeal)

(v) Coleoptile is a part found in the germinating maize. (castor/maize)

(vi) Alkaline pyrogallic acid is used for absorbing oxygen during experiments on germination. (oxygen/carbon dioxide)

1. Choose the correct answer from the options given below :

(i) Which one of the following plant parts is correctly matched with one of its stated characteristic ?
(a) Mango seed ....... aleurone layer
(b) Bean seed ........ endosperm
(c) Maize grain ........ coleoptile
(d) Wheat grain ........ exalbuminous
Answer: (c) Maize grain ........ coleoptile

(ii) Seeds sown very deep in the soil fail to germinate because they :
(a) cannot exert enough force to push the soil upward.
(b) do not get enough sunlight.
(c) get too much water.
(d) do not get enough oxygen.
Answer: (d) do not get enough oxygen.

(iii) Fruit is a ripened :
(a) Ovary
(b) Embryo
(c) Ovule
(d) Zygote
Answer: (a) Ovary

(iv) Which of the following is the largest seed ?
(a) Watermelon
(b) Pumpkin
(c) Double coconut
(d) Mango
Answer: (c) Double coconut

(v) The distinct whitish oval scar on the concave side of the seed is termed as :
(a) Scutellum
(b) Micropyle
(c) Hilum
(d) Germpore
Answer: (c) Hilum

(vi) The single cotyledon of a maize grain is called :
(a) Hypocotyl
(b) Scutellum
(c) Coleorhiza
(d) Embryo
Answer: (b) Scutellum

(vii) The outermost hard brownish layer of the seed coat is :
(a) Testa
(b) Tegmen
(c) Epicotyl
(d) Aleurone layer
Answer: (a) Testa

(viii) The part of an embryo which develops into root is :
(a) Coleorhiza
(b) Plumule
(c) Coleoptile
(d) Radicle
Answer: (d) Radicle

(ix) Which of the following statement holds true for a maize grain ?
(a) The maize grain is a ripened ovary containing a single seed.
(b) The fruit wall and seed coat are fused together.
(c) The outermost layer of the endosperm is rich in protein.
(d) All of the above.
Answer: (d) All of the above.

(x) Seema observed different kinds of seeds which can be categorised on the basis of certain features like cotyledons, endosperm, etc. She recorded her observations as follows :
P - Seeds are dicotyledonous and exalbuminous.
Q - Seeds are monocotyledonous and albuminous.
R - Cotyledons are rich in protein.
S - Stored food material is rich in starch.
Which of her above observations match with bean seeds ?
(a) R and Q
(b) Q and S
(c) S and P
(d) P and R
Answer: (d) P and R

(xi) Seeds germinate in two ways. The type in which the cotyledons remain underground is called (P) ....................... germination. During this type of germination, the (Q) ....................... elongates faster.
(a) P — Epigeal Q — Hypocotyl
(b) P — Epigeal Q — Epicotyl
(c) P — Hypogeal Q — Epicotyl
(d) P — Hypogeal Q — Hypocotyl
Answer: (c) P — Hypogeal Q — Epicotyl

1. Correct the following false statements by changing the first/last word only.

(a) Plumule develops into the root system.
Answer: Radicle develops into the root system.

(b) Testa is the thin inner layer of the seed coat.
Answer: Tegmen is the thin inner layer of the seed coat.

(c) Endothelium separates the endosperm and embryonic region in the maize grain.
Answer: Epithelium separates the endosperm and embryonic region in the maize grain.

(d) Hypocotyl elongates faster in hypogeal germination.
Answer: Epicotyl elongates faster in hypogeal germination.

(e) Germination is the period of rest in a seed.
Answer: Dormancy is the period of rest in a seed.

2. Name the following :

(a) A monocotyledonous endospermic seed.
Answer: Maize grain

(b) A chemical used in experiments, which absorbs oxygen.
Answer: Alkaline pyrogallic acid

(c) Part of the plumule above the embryonic axis of the seed.
Answer: Epicotyl

(d) A plant which shows viviparous germination.
Answer: Rhizophora (or Sonneratia)

(e) The layer of endosperm of maize, rich in protein.
Answer: Aleurone layer

(f) A seed with folded plumule leaves.
Answer: Bean seed

3. Give two examples of each of the following :

(a) Monocot albuminous seed.
Answer: Maize, wheat

(b) Dicot albuminous seed.
Answer: Poppy, custard apple

(c) Monocot non-endospermic seed.
Answer: Vallisneria, orchids

(d) Dicot non-endospermic seed.
Answer: Gram, pea

(e) Viviparous plant.
Answer: Rhizophora, Sonneratia

4. Given below is the longitudinal section of a maize grain. Match the structures marked (a) to (e) with their correct functions/characteristics.
(Note: Using labels (a) to (f) corresponding to the diagram and functions list)
1. Develops into the root system.
2. Single cotyledon.
3. Later forms the shoot.
4. Rich in protein.
5. Rich in starch.
6. Separates the endosperm and the embryonic part.

Answer:
(a) Radicle — 1. Develops into the root system.
(b) Plumule — 3. Later forms the shoot.
(c) Scutellum — 2. Single cotyledon.
(d) Aleurone layer — 4. Rich in protein.
(e) Endosperm — 5. Rich in starch.
(f) Epithelium — 6. Separates the endosperm and the embryonic part.

5. Fill in the blanks :

(a) In bean seeds, hypocotyl grows faster and the seeds are brought above ground.

(b) Coleorhiza is a protective layer of radicle and coleoptile protects the rolled plumule.

(c) A seed is protected by testa and tegmen.

(d) Seeds absorb water through micropyle which also helps in diffusion of respiratory gases.

(e) Rice, wheat, and maize are rich in starch food.

6. Arrange the following set of terms in order, so as to be in logical sequence. Rewrite the correct order.

(a) Embryo, 1st male gamete, zygote, egg cell, micropyle.
Answer: Micropyle, 1st male gamete, egg cell, zygote, embryo.

(b) Zygote, embryo, seed, allogamy, fusion of gametes.
Answer: Allogamy, fusion of gametes, zygote, embryo, seed.

(c) Tegmen, Embryonic axis, Cotyledons, Testa (arrange with respect to their position in a seed from outer to inner).
Answer: Testa, Tegmen, Cotyledons, Embryonic axis.

7. Match the terms given in column A with those of column B.

Column A — Column B
(a) Coleoptile — (i) Root system
(b) Coleorhiza — (ii) Cotyledon
(c) Radicle — (iii) Radicle
(d) Plumule — (iv) Plumule
(e) Scutellum — (v) Shoot system

Answer:
(a) Coleoptile — (iv) Plumule
(b) Coleorhiza — (iii) Radicle
(c) Radicle — (i) Root system
(d) Plumule — (v) Shoot system
(e) Scutellum — (ii) Cotyledon

8. Name the following :

(a) Two types of seeds on the basis of the number of cotyledons.
Answer: Monocotyledonous seeds and Dicotyledonous seeds.

(b) Two types of seeds on the basis of endosperm.
Answer: Albuminous (endospermic) seeds and Exalbuminous (non-endospermic) seeds.

(c) Three necessary conditions for the germination of seeds.
Answer: Water, suitable temperature, and oxygen (air).

(d) Two main types of germination.
Answer: Hypogeal germination and Epigeal germination.

(e) Two layers of the seed coat.
Answer: Testa (outer layer) and Tegmen (inner layer).

1. Define the following terms :

(a) Seed
Answer: A seed is a ripened ovule which contains an embryo that develops into a new plant.

(b) Fruits
Answer: A fruit is the enlarged ripened ovary of a flower, which encloses the seeds and helps in seed dispersal.

(c) Grain
Answer: A grain is actually a single-seeded fruit in which the fruit wall and the seed coat are completely fused together to form a protective layer.

(d) Dormancy
Answer: Dormancy is a period of physiological rest in a dry seed where the embryo remains inactive but alive.

(e) Germination
Answer: Germination is the process of formation of a seedling developed from the dormant embryo when placed under proper environmental conditions.

2. What is the difference between an embryo and a seed?
Answer: A seed is a ripened ovule consisting of a seed coat, stored food, and an embryo. The embryo, on the other hand, is the tiny living plant inside the seed (developed from the fused sperm nucleus and egg nucleus), comprising the radicle, plumule, and cotyledons, which will grow into a new plant.

3. Germinated grams are considered highly nutritive. What is the reason for this belief ? (LS)
Answer: During germination, the inactive embryo awakens, and enzymes convert complex stored food in the cotyledons into a diffusible, easily digestible form. The process also synthesizes vitamins and increases the availability of proteins and essential nutrients, making germinated grams highly nutritive.

4. Why do we not use the terms maize fruit and maize seed ? What do we say instead?
Answer: We do not use these terms because in maize, the ovary wall (fruit wall) and the seed coat are fused completely together to form a single inseparable protective layer. Therefore, it is a single-seeded fruit, and we refer to it as a "maize grain".

1. Distinguish between the following pairs :

(a) Monocotyledonous and Dicotyledonous seeds
Answer: Monocotyledonous seeds contain a single cotyledon (e.g., maize), whereas dicotyledonous seeds contain two cotyledons (e.g., bean).

(b) Epicotyl and Hypocotyl
Answer: Epicotyl is the region of the embryonic axis located above the point of attachment of the cotyledons and the plumule. Hypocotyl is the region of the embryonic axis located below the cotyledons.

(c) Epigeal and Hypogeal germination
Answer: In epigeal germination, the hypocotyl elongates faster, pushing the cotyledons above the ground. In hypogeal germination, the epicotyl elongates faster, leaving the cotyledons underground.

(d) Radicle and Plumule
Answer: The radicle is the part of the embryo that grows downwards to form the future root system. The plumule is the part that grows upwards to form the future shoot system (leaves and stem).

(e) Albuminous and Exalbuminous seeds
Answer: Albuminous (endospermic) seeds store their food inside a persistent endosperm, leaving the cotyledons thin and membranous. Exalbuminous (non-endospermic) seeds store their food directly in thick and fleshy cotyledons, and lack an endosperm at maturity.

2. What are the functions of the following in a seed?
(a) Seed coat
Answer: It protects the delicate inner parts of the embryo from mechanical injury and attacks by bacteria, fungi, and insects.
(b) Micropyle
Answer: It absorbs water when the seed is soaked, making it available for germination. It also allows for the diffusion of respiratory gases for the growing embryo.
(c) Cotyledons
Answer: They contain and provide stored food for the developing embryo and protect it.
(d) Radicle
Answer: It is the embryonic root which develops and grows downwards into the soil to form the root system.
(e) Plumule
Answer: It is the embryonic shoot which grows upwards above the soil to form the shoot system and first foliage leaves.

3. Suggest an experiment to prove that a suitable temperature is necessary for germination.
Answer: Take two beakers and name them A and B. Place some green gram seeds on wet cotton wool in each beaker. Keep beaker A in an ordinary room (which provides a suitable optimum temperature) and beaker B inside a refrigerator (very low temperature). After a day or two, the seeds in beaker A will germinate properly, while those in beaker B will not show signs of germination. This proves that a suitably warm temperature is necessary for germination.

4. Sometimes the potatoes kept in a basket during the late rainy season start giving out small shoots. Would you call it germination ? Give reason in support of your answer. (LS)
Answer: No, it cannot be called germination. Germination specifically refers to the development of a seedling from the dormant embryo contained within a seed. A potato is a modified underground stem (tuber), and the small shoots emerging from its "eyes" (buds) represent sprouting or vegetative propagation, not seed germination.

5. Give two differences in each of the following pairs :
(a) Coleorhiza and coleoptile.
Answer: 1. Coleorhiza is a protective sheath covering the radicle, whereas coleoptile is a protective sheath covering the plumule. 2. Coleorhiza is located at the lower pointed end of the embryonic region, while coleoptile is at the upper broader side.
(b) Bean seed and maize grain.
Answer: 1. Bean seed is a dicotyledonous exalbuminous seed, whereas maize grain is a monocotyledonous albuminous seed. 2. In bean seed, the seed coat is separate from the fruit wall (pod), whereas in maize grain, the seed coat and fruit wall are completely fused.
(c) Germination and vivipary.
Answer: 1. Normal germination occurs when a seed falls to the ground and finds suitable conditions (soil, water, temp). Vivipary is a special mode where the seed germinates inside the fruit while it is still firmly attached to the parent plant. 2. Germination is seen in typical plants like pea and maize, while vivipary is seen in marshy mangrove plants like Rhizophora.

6. Justify the statement that the maize grain is a 'one seeded fruit'.
Answer: The maize grain develops from a single ripened ovary. In this structure, the fruit wall (pericarp) and the seed coat (testa) are completely fused together forming a single inseparable protective layer enclosing a single seed. Therefore, technically and botanically, the maize grain is considered a single-seeded fruit.

7. What is the role played by the hypocotyl in epigeal germination ?
Answer: In epigeal germination, the hypocotyl elongates much faster than the epicotyl. As it grows, it forms an arch or loop above the soil, and then straightens up. By doing so, it physically pushes and pulls the cotyledons upwards above the ground, where they become the first green leaves.

8. Draw a neat and labelled diagram of :
(a) A twig of viviparous plant showing its germination.
(b) A seedling growing in soil.
Answer: (Please refer to Figure 6.8 and Figures 6.5 / 6.6 in your textbook to draw the required diagrams.)

9. Draw a neat and labelled diagram of the 'Experimental set-up of three-bean seed experiment' and mention the necessity of each condition for the germination of seeds.
Answer: (Please refer to Figure 6.4 in your textbook for the diagram.)
Necessity of each condition demonstrated:
1. The middle seed receives both oxygen (from the air) and water, so it germinates perfectly, proving both are necessary.
2. The top seed receives oxygen but no water, causing it to fail to germinate, proving water is necessary.
3. The bottom seed receives water but very little oxygen (only air dissolved in water), causing it to stop germinating after a small radicle emergence, proving oxygen is necessary.

1. The figure shown below represents the internal structure of a certain seed. Study the figure and answer the following questions.

(a) Identify the seed and mention whether it is mono or dicotyledonous.
Answer: It is a bean seed. It is dicotyledonous.

(b) Label the guidelines 1 to 4.
Answer: 1 - Plumule, 2 - Cotyledon, 3 - Seed Coat (Testa), 4 - Radicle.

(c) Write an important role of part 2.
Answer: Part 2 (Cotyledon) stores food material to provide nourishment for the developing embryo and also protects it.

(d) Mention the food component found in part 4.
Answer: Part 4 is the radicle, which does not act as a storage organ for food. The main food components (proteins and starch) are found in part 2 (the cotyledon). The radicle utilizes these nutrients for its rapid cell division and growth into the root system.

(e) What kind of germination takes place in the above mentioned seed ?
Answer: Epigeal germination.

2. Kiara visited a forest with marshy land. She observed that in some of the plants, the seeds germinate inside the fruit while still being attached to the parent plant. A part of the plant and a seedling are shown below in the diagram, answer the questions that follow. (SI)

(a) What kind of germination is shown above in the figure ?
Answer: Viviparous germination (Vivipary).

(b) Give two examples of the plants which germinate by this kind of germination.
Answer: Rhizophora and Sonneratia.

(c) Mention the part shown in the figure as 'A'.
Answer: Hypocotyl.

3. With regard to germination in bean seed, answer the following questions :

(a) State the function of the 'Micropyle'.
Answer: When soaked in water, the seed absorbs water mainly through the micropyle, making it available to the embryo for germination. It also allows for the diffusion of respiratory gases.

(b) Name the part of the seed that grows into the seedling.
Answer: The embryo (specifically the radicle and plumule).

(c) Name the part of the seed that provides nutrition for the growing seedling.
Answer: The Cotyledons.

(d) Draw a neat labelled diagram of a mature bean seed.
Answer: (Please refer to Figure 6.1 in your textbook to draw the diagram.)

(Choose the answer based on the codes given below.)
(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.
(d) A is false but R is true.

(i) Assertion (A) : Fruit is the enlarged ripened ovule which protects the seeds.
Reason (R) : Fruits develop from the ovary of the pistil after the process of pollination and fertilization. Ovarian wall forms the pericarp.
Answer: (d) A is false but R is true.

(ii) Assertion (A) : Dicotyledonous seeds are always exalbuminous (non-endospermic).
Reason (R) : All dicotyledonous seeds contain two cotyledons which store food material for the developing embryo.
Answer: (d) A is false but R is true.

(iii) Assertion (A) : Micropyle is the opening through which the pollen tube enters the ovule.
Reason (R) : Micropyle helps in the diffusion of respiratory gases for the growing embryo.
Answer: (b) Both A and R are true but R is not the correct explanation of A.

(iv) Assertion (A) : The single cotyledon of maize grain is termed as scutellum which does not store any food material for the developing embryo.
Reason (R) : Food material for the developing embryo is stored in the endosperm of the maize grain.
Answer: (a) Both A and R are true and R is the correct explanation of A.

(v) Assertion (A) : Epicotyl of the embryonic axis elongates faster in hypogeal germination.
Reason (R) : Epicotyl of the embryonic axis elongates faster in epigeal germination and the cotyledons remain underground.
Answer: (c) A is true but R is false.

1. Vinita has gone to her grandparents' home situated in a 'coastal village'. While visiting, she noticed that several fruits have fallen on the muddy shore. Unlike the seeds she had seen in other plants, these fruits already had long, green shoots emerging from them. Vinita observed that the already-sprouted seedlings easily anchored themselves in the soft mud, preventing them from being washed away by the tides. (SI)

(a) Mention the special mode of seed germination seen by Vinita in some plants of the coastal area.
Answer: Viviparous germination (Vivipary).

(b) What specific term is used to describe such plants in which the seed germinates inside the fruit itself?
Answer: Viviparous plants (Mangrove plants).

(c) Give two examples of the plants described above in (b).
Answer: Rhizophora and Sonneratia.

(d) Which part of the embryo appears much elongated during the above mentioned germination in (a) ?
Answer: Hypocotyl.

(e) How are these seeds adversely affected if they fall directly on to the marshy land ?
Answer: If they drop directly as normal un-germinated seeds, they would suffocate and fail to germinate because the marshy mud lacks proper oxygen supply required for respiration and germination.