III.ANSWER THE FOLLOWING IN BRIEF:
(1X4=4)
1. Write the events involved in the sexual reproduction of a flowering plant.
a. Discuss the first event and write the types.
b. Mention the advantages and the disadvantages of that event. briefly
Answers
Answer:
The sexual reproduction in flowering plants involves-
a) Pollination
b) Fertilization
a) Pollination: Transfer of pollen grains from the anther to the stigma of a flower is called pollination. Pollen grains are transferred by agents like air, water, insects etc.
Types of pollination
Self-pollination (Autogamy): When the pollen grains are transferred from the anther of a flower to the stigma of the same flower or another flower of the same plant it is known as self-pollination.
Cross-pollination (Allogamy): When the pollen grains are transferred to the stigma of another flower of a different plant it of the same species it is known as cross-pollination.
b) Advantages self-pollination
1. Self-pollination is certain in bisexual flowers.
2. Flowers need not depend on agents.
3. No wastage of pollen grains.
Disadvantages of Self-pollination
1. Seeds are less in number.
2. Seeds produce weak plants due to minute endosperm.
Advantages of cross-pollination
1. It leads to the production of new varieties.
2. More viable seeds are produced.
Disadvantages of cross-pollination
1. Plants have to depend on agents for pollination.
2. Wastage of Pollen grains occurs.