Question

Which of the following will not decrease inbreeding depression?

• A. Cross-pollination.
• B. Producing unisexual flowers.
• C. Unsynchronised pollen release and stigma receptivity.
• D. Anther and stigma growing up to same height in a bisexual flower.

Answer 1

The correct option is D Anther and stigma growing up to same height in a bisexual flower.

Continued self-pollination causes inbreeding depression. Inbreeding depression is the reduction in the biological fitness of the individuals of a population.

When anther and stigma grow up to same height in a bisexual flower, then there is high chance of pollen coming in contact with the stigma of the same flower resulting in self-pollination. This will certainly increase inbreeding depression.

To prevent self-pollination and promote cross-pollination, flowering plants have developed certain devices. These are called outbreeding devices which will decrease inbreeding depression.

Some of the outbreeding devices include:

i) The anthers and stigma in certain bisexual flowers are placed at different positions. This will prevent the pollen from coming in contact with the stigma of the same flower and thus prevents self-pollination.

ii) Producing unisexual flowers will also prevent self- pollination.

iii) In some species, pollen release and stigma receptivity is unsynchronised. Either the pollen is released before the stigma becomes receptive or stigma becomes receptive before the pollen is released and thus prevents self-pollination.