Identify the features developed by flowering plants to discourage self-pollination:
(A) Self incompatibility
(B) Synchronized pollen release and stigma receptivity
(C) Different positions of anther and stigma in a flower
(D) Producing bisexual flowers
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A) and (C) only
(A) Self incompatibility — A device against selfing. It is a genetic mechanism that stops pollen from fertilising ovules of the same flower or plant.
(B) Synchronized pollen release and stigma receptivity — Not a device against selfing. Selfing is prevented when pollen is released and the stigma becomes receptive at different times; synchronised timing favours self-pollination.
(C) Different positions of anther and stigma in a flower — A device against selfing. When the anther and stigma are placed apart, pollen cannot reach the stigma of the same flower.
(D) Producing bisexual flowers — Not a device against selfing. Bisexual flowers make self-pollination easier. Producing unisexual flowers is the device.
NCERT Extract:
Pollination – “… Flowering plants have developed many devices to discourage self-pollination and to encourage cross-pollination. In some species, pollen release and stigma receptivity are not synchronised. Either the pollen is released before the stigma becomes receptive or stigma becomes receptive much before the release of pollen. In some other species, the anther and stigma are placed at different positions so that the pollen cannot come in contact with the stigma of the same flower. Both these devices prevent autogamy. The third device to prevent inbreeding is self-incompatibility. This is a genetic mechanism and prevents self-pollen (from the same flower or other flowers of the same plant) from fertilising the ovules by inhibiting pollen germination or pollen tube growth in the pistil. Another device to prevent self-pollination is the production of unisexual flowers.”