Answer 1.
Importance of heredity:
Self-Pollination | Cross-Pollination |
Transfer pollen grains from the anther to the stigma of the same flower. | Transfer pollen grains from the anther to the stigma of a different flower. |
This process can take place in the same flower or a different flower of the same plant. | This process can take place between two flowers present on different plants. |
It occurs in the flowers which are genetically identical. | It occurs between flowers which are genetically different. |
Few species that exhibit self-pollination – Paphiopedilum parishii, Arabidopsis thaliana | Few species that exhibit cross-pollination – apples, daffodils, pumpkins and grasses |
Causes homogenous conditions in progenies. | Causes heterozygous condition in progenies. |
Self-pollination increases genetic uniformity and decreases genetic variation. | Cross-pollination decreases genetic uniformity and increases genetic variation. |
Causes inbreeding. | Causes outbreeding. |
Reduces the gene pool. | Maintains the gene pool. |
Produces limited amounts of pollen grains. | Produces large amounts of pollen grains. |
In self-pollination, both the stigma and anther simultaneously mature | In cross-pollination, both the stigma and anther mature at different times. |
Transfers a limited number of pollens. | Transfers large numbers of pollen. |
This process is carried out even when the flowers are closed. | For cross-pollination to happen, the flower should be open. |
No need for pollinators to transfer pollen grains. | Require pollinators to transfer pollen grains. |
Pollen grains are transferred directly to a flower’s stigma. | Pollen grains are carried via wind, insects, animals, water, etc. |