Question

A dioecious flowering plant prevents both :

• A. Autogamy and geitonogamy
• B. Geitonogamy and xenogamy
• C. Clesitogamy and xenogamy
• D. Autogamy and xenogamy

Answer 1

The Correct Option is A

To determine which types of pollination dioecious plants prevent, let's first understand the concepts:

• Autogamy: This is a type of self-pollination where the pollen from a flower's anther pollinates the same flower's stigma.
• Geitonogamy: This involves the transfer of pollen from the anther of one flower to the stigma of another flower on the same plant. Although geitonogamy involves two different flowers, it is still considered a form of self-pollination because both flowers are from the same plant.
• Xenogamy: This is cross-pollination where pollen is transferred between flowers of different plants, promoting genetic diversity.
• Cleistogamy: This is a type of self-pollination that occurs within a closed flower, ensuring self-pollination.

In dioecious plants, each plant is either male or female, meaning they contain only one sex of flowers. This separation naturally prevents:

1. Autogamy: No self-pollination can occur within the same flower because dioecious plants do not have both male and female reproductive organs in the same flower.
2. Geitonogamy: As the flowers of only one sex are present on each plant, pollen cannot transfer between flowers on the same plant to fertilize them, preventing geitonogamy.

Given these explanations, the correct option is:

Autogamy and geitonogamy