Question

Both, autogamy and geitonogamy are prevented in

• A. Papaya
• B. Cucumber
• C. Castor
• D. Maize

Answer 1

The Correct Option is A

To understand why both autogamy and geitonogamy are prevented in papaya, let's break down the definitions of these terms and examine how papaya's reproductive structure prevents them.

Definitions:

• Autogamy: It is a form of self-pollination where the pollen from a flower pollinates the same flower or another flower on the same plant.
• Geitonogamy: It involves the transfer of pollen to different flowers on the same plant, essentially a form of self-pollination at the intraplant level.

Papaya, scientifically known as Carica papaya, is dioecious. This means that individual plants are either male or female. Here’s how this characteristic prevents both autogamy and geitonogamy:

1. Dioecious Nature: In dioecious plants like papaya, male and female flowers exist on separate plants. This separation of sexes onto different plants prevents both autogamy and geitonogamy because a single plant cannot have both male (pollen-producing) and female (ovule-receiving) components.
2. Need for Cross-Pollination: As male and female flowers are on different plants, pollination requires the transfer of pollen from a male plant to a female plant, thus ensuring cross-pollination.

Explanation of Other Options:

• Cucumber: Though predominantly monoecious (having both male and female flowers on the same plant), self-pollination can occur within the same plant.
• Castor: This plant is monoecious, where both male and female flowers are on the same plant, allowing the possibility of geitonogamy.
• Maize: Also monoecious and predominantly wind-pollinated, maize may undergo geitonogamy.

In conclusion, papaya is the correct answer because its dioecious nature inherently prohibits both autogamy and geitonogamy, necessitating cross-pollination for reproduction.