Question

Assured seed set is possible even in absence of pollinators when flower is
A. Xenogamous
B. Chasogaous
C. Geitonogamous
D. Cleistogamous

Answer 1

Hint: Pollen grains come in contact with the stigma to affect pollination in the flowers buds during the anthers dehisce. Cleistogamous flowers are invariably autogamous on the stigma there no chances of the cross pollen taking place. In the absence of pollinators, cleistogamous flowers produce assured seed sets.

Complete answer:
Flowers in which the pollen are transferred from the anther to the stigma in the xenogamous flowers on the different plants. Xenogamous flowers are dependent on the external agencies for pollination and a type of cross pollinated. In which self-pollination and cross pollination occurred on the stigma and anthers known as the type of chasmogamous flowers. Chasmogamous flowers depend upon the cross pollination of the external agencies.
And in which pollen is transferred from the anther to stigma of the same plant but different flowers called a geitonogamous type of flowers. And need external agencies for the cross pollination process. In which flowers never open and only self-pollination occurred within the unopened flowers known as the name cleistogamous. Cleistogamous flowers known as in which bisexual flowers do not open at all. But stigma and anthers lie close to each other and on the flower buds, pollen grains come into contact with the stigma part in which pollination takes place. And the type of cleistogamous flowers do not depend upon the external agencies for pollination. And in the absence of pollinators seed set in the cleistogamous but not dependent upon the pollinators.

Therefore the correct option is (D).

Note: Closed flowers where the gynoecium and androecium is not exposed to the other flowers are the type of cleistogamous flowers. And pollen pistil interaction between the same flowers an assured seed set is produced without the help of pollinators according to the process occurred in the cleistogamous flowers.