Selina Concise Class 9 Biology Solution Chapter No. 6- ‘Seed-Structure and Germination’ For ICSE Board Students
Seed-Structure and Germination
A)
1) Answer : c) Maize grain ____________ coleoptile.
In maize grain, the coleorhiza and coleoptile are the two protective sheaths which is seen as membranous covering.
2) Answer: d) Do not get enough oxygen
The deep seeds do not germinate because they get water but small amount of oxygen. If the deep seed does not get enough oxygen, they stops germinating.
B)
1)
- a) False
- b) True
- c) True
- d) True
2)
a) Answer: Maize, grasses
b) Answer: Pyrogallic acid
c) Answer: Shoot
d) Answer: Rhizophora
e)
Answer: Aleurone layer
f) Answer: Bean
3)
a) In bean seeds, plumule grows faster and the seeds are brought above
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) Seed absorb water though micropyle which also helps in diffusion of respiratory gases.
e) Rice, wheat, and maize are rich in starch
4)
a) Micropyle, 1st male gamete, egg cell, zygote, embryo.
b) Allogamy, fusion of gametes, zygote, embryo, seed.
c) Seed coat bursts, radicle grows downward, hypocotyls form loop above the soil, epicotyls elongate.
C)
1)
Seed |
Embryo |
Seed contains an embryo that later develops into new plant. | If embryo is exposed to favorable condition it will germinate and it is inactive within seed. |
2) Answer:
Endospermic (albuminous) seeds- Cereals, poppy, custard apple
Non-endospermic (exalbuminous) seeds- Mustard, Mango, Pea, Gram
3) Answer:
The endosperm provides food to the cotyledon of seed and it is nutritive. Its layer is rich in protein and starch. Because of this reason, the germinated gram are considered highly nutritive.
4) Answer:
The maize is basically a single seeded fruit where fruit wall and the seed coat both are fused together. The fusion forms a protective layer that’s why we do not call it a fruit. We call that fruit as grain.
D)
1) a) Seed coat: The delicate inner parts of the seed from injury and from attack of fungi, bacteria and insects is protected by seed coat.
b) Micropyle: It allows entry of water to seed through its pore during germination.
c) Cotyledon: It contains food for the embryo and protect it.
d) Radicle: It forms root.
e) Plumule: It form shoot.
2) Answer:
To prove that a suitable temperature is necessary for germination the following experiment is suggested:
For the experiment we need two beakers, wet cotton wool and refrigerator. Give name ‘A’ to a beaker and ‘B’ for another beaker.
Place wet cotton wool in each beaker and add some gram seed in it. For the proper experiment you need to keep ‘A’ beaker at ordinary room temperature and another ‘B’ beaker in the refrigerator. If you check both the beaker after 1-2 days, you will see beaker A will germinate with respect to aim of the experiment and beaker B will not show germination or can germinate after several days.
Hence, seeds require a suitable temperature for germination.
3. Answer:
The epicotyl and hypocotyl elongates during germination process. All the changes of potato leads to the formation of seedling or germination. Yes, we can say it is germination due to these changes of small shoots.
4)
a)
Epigeal germination |
Hypogeal germination |
Cotyledons in epigeal germination are pushed above ground. | Cotyledons of hypogeal germination remain underground. |
During germination, hypocotyl elongates. | During germination, epicotyl elongates. |
b)
Coleorhiza |
Coleoptile |
It is a protective sheath of radicle. | It is a protective sheath of plumule. |
It is present towards pointed end of embryonic region. | It is present towards upper broader side of embryonic region. |
c)
Bean seed |
Maize seed |
Have two cotyledons | Have one cotyledon |
Don’t have endosperm | Have large endosperm |
5) Answer:
In the germination, the embryo which is inactive within seed becomes activated. It begins to grow in a new plant and then it is known for germination. In the vivipary, when the germination of seed occurs within fruit then it is called as vivipary. But it is attached to parent plant.
6) Answer:
The ovarian wall of the fruit forms fruit wall that encloses the seeds. The fruit is enlarged ripened ovary and it protects seeds. The Maize grain is single-seeded fruit with fruit wall and seed coat fused. So, it is called as grain not a fruit.
7) Answer:
Seed germination that takes place or occurs above the ground is called as epigeal germination. The cotyledons are pushed above ground when hypocotyl elongates. And hypocotyl forms a loop above the soil.
8) Answer:
a) Function of micropyle: 1) The seeds absorb water by the micropyle and it makes it available to the germination of embryo. 2) Micropyle provides for the diffusion of respiratory gases for growing embryo.
b) The embryo part of the seed grows into the seedling.
c) The cotyledon part of the seed provide nutrition for the growing seedling.
d)
Solution:-