Question

Q. Why is meiosis needed in species that reproduce sexually?
Q. What are the various adaptations found in plants for cross pollination ? Describe any two of them.

Answer 1

Dear Student,

17. Meiosis is necessary in order to maintain ploidy level with variations from generation to generation.
The normal chromosome number is restored in a diploid cell when two haploid gametes fuse during fertilization, and hence meiosis is necessary for sexually reproducing organisms. If meiosis does not occur during gamete formation, the number would be doubled every time during fertilization.

18. Adaptation found in plants for cross pollination are:
1. Dichogamy- Maturation of anthers and stigmas at different times, if anthers mature earlier this is called protandry. If stigma matures first, this is called protogyny. This way cross-pollination is favoured.
2. Self-sterility - In this adaptation, a flower cannot be pollinated by the pollen grains of the same flower or from any flower of the same plant, so cross-pollination is the only option.

Regards