NCERT Class VII Science Solutions: Chapter 12-Reproduction in Plants Part 3

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Question 6:

Explain the difference between self-pollination and cross-pollination.

Answer:

Self-pollination is the transference of the pollen grains from the anther to the stigma of either the same or genetically similar flower.

Cross pollination is defined is defined as the deposition of pollen grains from anther of a flower to the stigma of a different flower of another plant of same or different species.

Difference between self and cross pollination

S. No.

Self-Pollination

Cross-Pollination

1.

Pollen grains are transferred to stigma of same flower.

Pollen grains are transferred to stigma of different flower.

2.

Pollinating agent is not required.

Pollinating agent such as wind, water, insects, etc. is not required.

3.

Examples: Peanuts, sunflower, etc.

Examples: Mango, rose and most of the flowering plants.

Question 7:

How does the process of fertilization take place in flowers?

Answer:

Once pollen grain spreads on the stigma, it produces a pollen tube. This process is called germination of pollen grain. The pollen tube penetrates the style and reaches the ovary. Male nucleus is transferred through this pollen tube. Finally, fusion of male and female nuclei takes place inside the ovary. This step is called fertilization.

This picture shows Pollination and Fertilization of a flower

Pollination and Fertilization of a Flower

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