Multiple Choice Type
Which one of the following plant parts is correctly matched with one of its stated characteristic?
- Mango seed → aleurone layer
- Bean seed → endosperm
- Maize grain → coleoptile ✓
- Wheat grain → exalbuminous
Seeds sown very deep in the soil fail to germinate because they
- cannot exert enough force to push the soil upward.
- do not get enough sunlight.
- get too much water.
- do not get enough oxygen ✓
Very Short Answer Type
Are the following statements true (T) or false (F)?
- Some seeds have no cotyledons at all
- Maize grain is fruit and not a seed
- Seeds fallen in a flower-bed from the previous crop usually do not germinate until the next sowing season
- Oxygen is necessary for the germination of seeds.
Name the following:
- A monocotyledonous endospermic seed.
- A chemical used in experiments which absorbs oxygen.
- Part of the plumule above the embryonic axis of the seed.
- A plant which shows viviparous germination.
- The layer of endosperm of maize rich in protein.
- A seed with folded plumule leaves.
- Pyrogallic acid
- Aleurone layer
Fill in the blanks:
- In bean seeds, __________ grows faster and the seeds are brought __________ ground.
- __________ is a protective layer of radicle and __________ protects the rolled plumule.
- A seed is protected by __________ and __________.
- Seeds absorb water through __________ which also helps in diffusion of respiratory gases.
- Rice, wheat and maize are rich in __________ food.
- plumule, above
- Coleorhiza, coleoptile
- seed coat, testa
Arrange the following set of terms in order, so as to be in logical sequence. Rewrite the correct order.
- Embryo, 1st male gamete, zygote, egg cell, micropyle.
- Zygote, embryo, seed, allogamy, fusion of gametes.
- Seed coat bursts, hypocotyls elongates, radicle grows downward, hypocotyls forms loop above the soil, epicotyls elongates.
- Micropyle, 1st male gamete, egg cell, zygote, embryo.
- Allogamy, fusion of gametes, zygote, embryo, seed.
- Seed coat bursts, radicle grows downward, hypocotyls form loop above the soil, epicotyls elongate.
Short Answer Type
What is the difference between an embryo and a seed?
|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, then it germinates.|
Give any two examples each of endospermic (albuminous) seeds, and non-endospermic (exalbuminous) seeds.
- Endospermic (albuminous) seeds — Castor, Maize, Poppy.
- Non-endospermic (exalbuminous) seeds — Bean, Gram, Pea.
Germinated grams are considered highly nutritive. What is the reason for this belief?
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.
Why do we not use the terms maize fruit and maize seed? What do we say instead?
A fruit is a fertilised ovary and a seed is a fertilized matured ovule which contains an embryo or a growing plant. 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.
Long Answer Type
What are the functions of the following in a seed?
- Seed coat
Seed coat — A seed coat protects the internal parts of a seed. The seed coat has two layers. The outer layer is thick and known as the testa . The inner layer is thin and known as tegmen.
A thick seed coat protects the seed from sunlight and water. It also protects the delicate inner parts of the seed from injury and the attack of bacteria, fungi and insects.
Micropyle — It is a tiny pore situated close to the hilum. It marks the opening through which the pollen tube had entered the ovule.
Micropyle serves two functions:
- During germination, micropyle allows water to enter the seed through its pore.
- It provides for the diffusion of respiratory gases for the growing embryo.
Cotyledons — They contain food for the embryo.
Radicle — It forms the future root.
Plumule — It forms the future shoot.
Suggest an experiment to prove that a suitable temperature is necessary for germination.
Aim — To prove that a suitable temperature is necessary for germination.
Apparatus — Two beakers, wet cotton wool, refrigerator
(1) Take two beakers and label them as A and B.
(2) Place some gram seeds on wet cotton wool in each of the beakers.
(3) Keep beaker A at ordinary room temperature and beaker B in the refrigerator.
(4) 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.
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.
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.
Give two differences in each of the following pairs:
- Epigeal germination and hypogeal germination
- Coleorhiza and coleoptile
- Bean seed and maize grain
- Epigeal germination and Hypogeal germination
|Epigeal germination||Hypogeal germination|
|Germination of a plant that takes place above the ground.||Germination of a plant that takes place below the ground.|
|Cotyledons emerge out of the soil.||Cotyledons remain inside the soil.|
|Hypocotyl elongates||Epicotyl elongates|
- Coleorhiza and 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|
- Bean seed and Maize grain
|Bean seed||Maize grain|
|Two cotyledons||One cotyledon|
|No endosperm||Large endosperm present|
Differentiate between germination and 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.|
Justify the statement that the maize grain is a 'one seeded fruit'.
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.
What is the role played by the hypocotyl in epigeal germination?
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.
With regard to germination in bean seed, answer the following questions:
- State the function of the 'micropyle'.
- Name the part of the seed that grows into the seedling.
- Name the part of the seed that provides nutrition for the growing seedling.
- Draw a neat labelled diagram of a mature bean seed.
- The 'micropyle' serves two important functions:
- Allows absorption of water and makes it available to the embryo for germination.
- Enables diffusion of respiratory gases for the growing embryo
- The embryo of the seed grows into the seedling.
- The cotyledons of the seed provide nutrition for the growing seedling or the embryo.
- Below is the diagram of a mature bean seed: