Question

Read the following statements, and choose the correct option.
A. Transfer of pollen grains from anther to stigma of same flower.
B. Transfer of pollen grain from anther to stigma of anther flower of same plant.
C. Transfer of pollen grain from anther to stigma of flower of different plant.

• A. A–Autogany; B–Geitonogamy; C–Xenogamy
• B. A–Homogamy; B–Autogamy; C–Allogamy
• C. A–Allogamy; B–Geitonogamy; C–Allogamy
• D. A–Autogamy; B–Xenogamy; C–Geitonogamy

Answer 1

Answer: (A)

Transfer of pollen grains shed from the anther to the stigma of a pistil is termed as pollination. Flowering plants have an array of adaptations to achieve pollination.
Different types of pollination are -
1. Autogamy- In this type of pollination, pollen is transferred from the anther to the stigma of the same flower.
Flowers which open and expose the anther and stigma or the Chasmogamous flowers, complete autogamy is rare.
Autogamy in these flowers requires synchronisation in release of pollen and receptivity of stigma, and also the anther and stigma of these flower should be close to each other so that self-pollination became easy.
Some plants such as Viola, Oxalis and Commelina produce two types of flower- the normal Chasmogamous flowers which expose their anther and stigma; and Cleistogamous flowers which do not open at all.
In such flowers, anther lies close to stigma. When the anther dehisce in the flower bud, pollen grains come in contact with the stigma to effect pollination.
In Cleistogamous flowers production of seed is sure even if pollinators are absent.
2. Geitonogamy- (Geiton means neighbour) Transfer of pollen grains from the anther to stigma of another flower of same plant. It is functionally cross-pollination, but genetically self-pollination.
3. Xenogamy- Transfer of pollen grains from anther to stigma of another flower on a different plant of same species.
It is the only type of pollination in which genetically different pollen grains are brought upto stigma, so it helps in genetic recombination of traits.