Seeds || Living Beings

Seeds || Germination of seeds || Pollination || Living beings || Dispersion of seeds

1) What is seed? Write its type.
Ans: A seed is a fertilized ovule. Flowering plants produce seeds. Seeds of different plants vary in shapes and sizes. On the basis of cotyledon structure, there are two types of seeds. They are;
 a) Monocotyledonous seeds

 b) Dicotyledonous Seeds

2. Define monocotyledonous and dicotyledonous seeds.
Ans: 

Monosotyledonous seed: The seed which contain single cotyledon, are called monocotyledonous seeds. These seeds contain very small embryo. They contain large endosperm. For example: maize, wheat, rice, etc.
Dicotyledonous Seeds: The seed which contain two cotyledonous are called dicotyledonous seeds. These seeds have very large embryo. They contain large plumule. For example: Pea, Bean, Gram, etc.

3. Differentiate between monocotyledonous and dicotyledonous seeds. 

Ans: The differences between monocotyledonous and dicotyledonous seeds are:

Monocotyledonous Seed	Dicotyledonous Seed
Contain single cotyledon.	Contains two cotyledon.
Endosperm is present.	Endosperm is absent.
We can not see hylum and micropyle with our naked eyes.	We can see hylum and micropyle with our naked eyes.
Embryo is smalle.	Embryo is large.
Plumule is very small.	Plumule is very large.
Single grain act as a seed.	Seeds are present inside the fruit.
For example: Maize, Rice, Wheat, etc.	For example: Pea, Bean, Gram, etc.

4. Write any three functions of a seed.

Ans: The following are the functions of a seed;

i)                    All seeds develop into new plants under suitable environment condition.

ii)                   Seeds store food either in endosperm (maize) or cotyledons (pea). Stored food is used by embryo for its germination.

iii)                 A seed coat protects the embryo during adverse condition.

5. What is meant by dispersal of seeds? How do the seeds of plants dispersed?
Ans: The distribution of seeds from one place to another place by different methods is called dispersal of seeds. Because of seed dispersal plants of same varities are found in different places. When the dispersed seeds get suitable condition germinate into new plant.
The agents of seed dispersal are listed below: 

a) Dispersal by wind: Very small seeds, seeds with fiber, winged seeds, and hairy seeds are dispersed by wind. Such seeds are carried by wind away from the parent plants. Sometimes the seeds are carried 100 km away. For example: Cotton, poppy, maple, simal (bombax), dandelim, etc.
b) Dispersal by water: Water is the common agent of seed dispersal. The seeds of aquatic plants and seeds of shore plants are dispersed by water. For example: Walnut, Coconut, Water Lily, etc.
c) Dispersal by mechanical methods: The fruits of some plants dry up and burst. The bursting of fruits causes the seed dispersal. The seeds dispersed near the parent plant. For example: Pea, Balsam, Ben, Ladys finger, etc.
d) Dispersal by Animals: Different animals help in seed dispersal of different plants. Some undigested seeds are dispersed through the faces. For example: guava, tomato, etc. Some seeds have hooks and spines. Such seeds are attached to the clothes and hair (fur) of the animals and dispersed into the another place. For example: xanthium, speargrass, tigers’ claw.

6. Define germination of seed and explain about it.

Ans: The process of growing an embryo of a seed into new baby plant is called germination. 

The seeds of some plant germinate immediately after dehiscence in the soil but seeds of some plants do not germinate immediately. They need some resting period. When the seeds get suitable condition, germinate into new plant. Seeds of some plant can live without germination for many years, if they do not get favourable condition, proper amount of water, enough oxygen and good temperature are the conditions of seed germination.

7. What do you mean by zygote?

Ans: Zygote is a diploid structure formed due to fusion of two haploid male and female gametes produced by male and female organism. Diploid chromosomes are present in zygote.

8. Define pollination. List the types of pollination.

Ans: The process of transfer of pollen grains from the anther to the stigma of flower is called pollination. 

There are two types of pollination. They are; 

a) Self-pollination 

b) Cross-pollination

9. Define self-pollination and cross-pollination with example.

Ans: 

Self-pollination is the process of transfer of pollen grains from the anther to the stigma of a same flower. For example: flower of pea, cotton, etc. 

Cross-pollination is the process of transfer of pollen grains from the anther of a flower of one plant to stigma of a flower of other plants of same species.

10. Differentiate between self-pollination and cross-pollination. 
Ans: The following are the difference between self pollination and cross pollination:

Self-pollination	Cross-pollination
It is the transfer of pollen grain that takes place from anther to stigma of same flower or another flower of same plant.	It is the transfer of pollen grains that takes place from anther of flower of one plant to stigma of a flower of another plants.
External agents are not required for self pollination.	External agents like wind, water, insects, etc are required for cross pollination.
Variation is not seen.	Variation occurs.
Self pollination specially occurs in bisexual flowers.	It is common in both unisexual and bisexual flowers.