ICSE Solutions for Chapter 6 Seeds: Structure and Germination Class 9 Biology Selina
Progress Check
1. Mention whether the following statements are True (T) or False(F)
(i) Plumule is the future root and radicle the future shoot of the plant. T/F
(ii) Micropyle serves for the emergence of the radicle. T/F
(iii) Cotyledons in castor are a big store of food for the embryo. T/F
(iv) Maize grain has a large endosperm. T/F
(v) Tegmen is the outmost layer of the seed. T/F
Solution
(i) The statement is false. The plumule is the future shoot and the radicle is the future form of root.
(ii) The statement is true.
(iii) The statement is true.
(iv) The statement is true.
(v) The statement is false. It is a thin layer lying next to the testa.
2. Fill in the blanks by choosing the correct alternative
(i) In a dry seed the embryo is in ____ state.(active/quiescent)
(ii) Water is absorbed by the seed mainly through ____ . (entire surface/micropyle)
(iii) Very low temperature _____ the growth of embryo (inhibits/destroys)
(iv) Germination in pea is _____ . (epigeal/hypogeal)
(v) Coleoptile is a part found in the germinating (castor/maize).
(vi) Alkaline pyrogallic acid is used for absorbing _____ during experiments on germination. (oxygen/carbon dioxide)
Solution
(i) Quiescent
(ii) Micropyle
(iii) Inhibits
(iv) Hypogeal
(v) Maize
(vi) Oxygen
Review Questions
A. Multiple Choice Type
1. 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
Solution
(c) Maize grain - coleoptile
The plumule of the maize pierces through its protective sheath, the coleoptile to grow upwards. It is one of the protective sheaths.
2. 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 to much water.
(d) Do not get enough oxygen.
Solution
(d) Do not get enough oxygen
For germination of the seeds sown, oxygen is required.
B. Very Short Answer Type
1. Answer the following statements true (T) or false (F)?
(a) Some seeds have no cotyledons at all. T/F
(b) Maize grain is fruit and not a seed. T/F
(c) Seeds fallen in a flower-bed from the previous crop usually do not germinate until the next sowing season. T/F
(d) Oxygen is necessary for the germination of seeds. T/F
Solution
(a) The statement is false. Some seeds have one cotyledon (monocots) while others have two cotyledons (dicots).
(b) The statement is true.
(c) The statement is true.
(d) The statement is true.
2. Name the following:
(a) A monocotyledonous endospermic seed.
(b) A chemical used in experiments, which absorbs oxygen.
(c) Part of the plumule above the embryonic axis of the seed.
(d) A plant which shows viviparous germination.
(e) The layer of endosperm of maize, rich in protein.
(f) A seed with folded plumule leaves.
Solution
(a) Maize
(b) Pyrogallic acid
(c) Shoot
(d) Rhizopora
(e) Aleurone layer
(f) Bean
3. Fill in the blanks:
(a) In bean seeds, ____ grows faster and the seeds are brought ____ ground.
(b) ____ is a protective layer of radicle and ____ protects the rolled plumule.
(c) A seed is protected by ____ and ____.
(d) Seeds absorb water through ____ which also helps in diffusion of respiratory gases.
(e) Rice, wheat, and maize are rich in ____ food.
Solution
(a) In bean seeds, Plumule 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 Seed coat and testa.
(d) Seeds absorb water through Micropyle which also helps in diffusion of respiratory gases.
(e) Rice, wheat, and maize are rich in starch food.
4. 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.
(b) Zygote, embryo, seed, allogamy, fusion of gametes.
(c) Seed coat bursts, hypocotyl elongates, radicle grows downwards, hypocotyl forms loop above the soil, epicotyl elongates.
Solution
(a) Micropyle, 1st male gametes, egg cell, zygote, embryo.
(b) Allogamy, fusion of gametes, zygote, embryo, seed.
(c) Seed coat bursts, radicle grows downwards, hypocotyls from loop above the soil, epicotyl elongate
C. Short Answer Type
1. What is the difference between an embryo and a seed?
Solution
|
Seed |
Embryo |
|
It is a mature ovule after fertilization. |
Embryo remains within the seed in an inactive or dormant state. |
|
It contains a tiny living-plant called the embryo. |
When embryo is exposed to favourable conditions, when it germinates. |
2. Give any two examples each of endospermic (albuminous) seed, and non-endospermic (exalbuminous) seeds.
Solution
Endosperrnic (albuminous) seeds: E.g. Castor, Maize, Poppy Non-endospermic (exalbuminous) seeds:
Example: Bean, Gram, Pea
3. Germinated grams are considered highly nutritive. What is the reason for this belief?
Solution
Germinated grams are considered highly nutritive because the cotyledon of the seed absorbs food from the endosperm, making it nutritive. It is rich in starch and its outermost layer is rich in protein.
4. Why do we not use the terms maize fruit and maize seed? What do we say instead?
Solution
Maize grain is actually a fruit in which the fruit wall and the seed coat are fused together to form a protective layer. Therefore, we do not use the terms maize fruit and maize seed. Instead, we call such fruits as grains.
D. Long Answer Type
1. What are the functions of the following in a seed?
(a) Seed coat
(b) Micropyle
(c) Cotyledons
(d) Radicle
(e) Plumule
Solution
(a) Seed coat: It protects the delicate inner parts of the seed from injury and the attack of bacteria, fungi and insects.
(b) Micropyle: During germination, micropyle allows water to enter the seed through its pore.
(c) Cotyledons: They contain food for the embryo.
(d) Radide: It forms the future root.
(e) Plumule: It forms the future shoot.
2. Suggest an experiment to prove that a suitable temperature is necessary for germination.
Solution
Aim: To prove that a suitable temperature is necessary for germination.
Apparatus: Two beakers, wet cotton wool, refrigerator.
Procedure:
(i) Take two beakers and label them as A and B.
(ii) Place some gram seeds on wet cotton wool in each of the beakers.
(iii) Keep beaker A at ordinary room temperature and beaker B in the refrigerator.
(iv) In 1-2 days, the seeds in beaker A will germinate, showing the importance of a suitable temperature for germination. Seeds in beaker B may not show the signs of germination or may germinate after several days, though not to the extent as the seeds in beaker A.
Inference: Seeds require a suitable temperature for germination.
3. Sometimes the potatoes kept in a basket during the rainy season start giving out small shoots. Would you call it germination? Give reason in support of your answer.
Solution
Yes, we call it germination because all the changes leading to the formation of a seedling collectively constitute germination. During germination, either the epicotyl or the hypocotyl elongates.
4. Give two differences in each of the following pairs:
(a) Epigeal germination and hypogeal germination
(b) Coleorhiza and coleoptile.
(c) Bean seed and maize grain.
Solution
(a) Difference between Epigeal germination and hypogeal germination
|
Epigeal germination |
Hypogeal germination |
|
Cotyledons are pushed above the ground. |
Cotyledons remain underground. |
|
Hypocotyl elongates. |
Epicotyl elongates |
(b) Difference between Coleorhiza and coleoptile
|
Coleorhiza |
Coleoptile |
|
Protective sheath of radicle. |
Protective sheath of plumule. |
|
Present towards the pointed end of embryonic region. |
Present towards the upper broader side of the embryonic region. |
(c) Difference between Bean seed and maize grain
|
Bean seed |
Maize grain |
|
Two cotyledons |
One cotyledon |
|
No endosperm |
Large endosperm present |
5. Differentiate between germination and vivipary.
Solution
|
Germination |
Vivipary |
|
When the embryo in the seed becomes activated and begins to grow into a new plant, then it is known as germination. |
Vivipary is known as the germination of seed within the fruit, while it is still attached to the parent plant |
6. Justify the statement that the maize grain is a ‘one seeded fruit’.
Solution
A fruit is the enlarged ripened ovary in which the ovarian wall forms the fruit wall and encloses the seed. The fruit protects the seed and helps in seed dispersal.
The maize grain is regarded as a ‘one seeded fruit' because the fruit wall and the seed coat are fused to form a protective layer. Such a fruit is called grain.
7. What is the role played by the hypocotyl in epigeal germination?
Solution
Germination of a seed which takes place above the ground is called epigeal germination. In epigeal germination, the hypocotyl grows forming a loop above the soil. It then straightens pushing the cotyledons above the ground.
8. With regard to germination in bean seed, answer the following questions:
(a) State the function of the ‘Micropyle’.
(b) Name the part of the seed that grows into the seedling.
(c) Name the part of the seed that provides nutrition for the growing seedling.
(d) Draw a neat labeled diagram of a mature bean seed.
Solution
(a) The 'micropyle' serves two important functions:
(i) Allows absorption of water and makes It available to the embryo for germination.
(ii) Enables diffusion of respiratory gases for the growing embryo.
(b) The embryo of the seed grows into the seedling.
(c) The cotyledons of the seed provide nutrition for the growing seedling or the embryo.
(d) Structure of embryo
