Outbreeding devices and pollen-pistil interaction — NEET & JEE Questions

Question 1 · difficulty L1 · recall

What is self-incompatibility in flowering plants?

• A. A genetic mechanism that prevents self-pollen from effecting fertilisation
• B. A failure to produce pollen grains
• C. A lack of ovules in the ovary
• D. A type of vegetative propagation

Question 2 · difficulty L2 · understanding

How does dichogamy promote outbreeding?

• A. The flower produces no pollen
• B. Anthers and stigma become functionally mature at different times
• C. The ovary develops before pollination
• D. The plant produces only one flower

Question 3 · difficulty L2 · understanding

How can herkogamy reduce self-pollination?

• A. By destroying pollen after germination
• B. By preventing meiosis
• C. By spatially separating anthers and stigma
• D. By eliminating the stigma

Question 4 · difficulty L2 · understanding

In papaya, male and female flowers are borne on different plants. This condition, which prevents both autogamy and geitonogamy, is called

• A. dioecy
• B. monoecy
• C. self-incompatibility
• D. cleistogamy

Question 5 · difficulty L3 · application

A pollen grain lands on a compatible stigma and begins to germinate. Which event normally follows?

• A. The stigma develops into a seed
• B. The ovary immediately becomes a fruit
• C. The pollen grain undergoes meiosis
• D. The pollen tube grows through the style toward the ovule

Question 6 · difficulty L3 · application

A bisexual flower has functional pollen and ovules, but its anthers and stigma are positioned so that self-pollen rarely contacts the stigma. Which interpretation is most appropriate?

• A. The flower must be male sterile
• B. The flower uses a structural outbreeding device without being unisexual
• C. The plant cannot reproduce sexually
• D. Self-incompatibility is the only possible mechanism

Question 7 · difficulty L3 · application

In a bisexual flower the anthers dehisce two days before the stigma of the same flower becomes receptive. What is this an example of, and what does it achieve?

• A. Self-incompatibility; it prevents pollen germination
• B. An outbreeding device based on non-synchronised pollen release and stigma receptivity; it discourages autogamy
• C. Dioecy; it prevents geitonogamy
• D. Cleistogamy; it ensures self-pollination

Question 8 · difficulty L3 · application

Pollen from a plant is dusted onto the stigma of the same plant but fails to germinate, whereas the same pollen germinates on a stigma of a different plant of the species. Which device is operating?

• A. Dioecy
• B. Positional separation of anther and stigma
• C. Self-incompatibility, a genetic mechanism that inhibits self-pollen from germinating or growing a pollen tube in the pistil
• D. Emasculation

Question 9 · difficulty L4 · analysis

Pollen from plant X germinates well on the stigma of plant Y, but pollen-tube growth is later arrested in the style because of recognition between pollen and pistil. What does this show?

• A. Pollen-pistil interaction can determine compatibility after pollen lands
• B. Any pollen that germinates must complete fertilisation
• C. The style has no role in reproductive recognition
• D. Pollen compatibility depends only on wind direction

Question 10 · difficulty L4 · application

A breeder wants to cross two varieties of a species with bisexual flowers, and a second species with unisexual flowers. Which pair of procedures is correct?

• A. Bisexual: bagging alone; unisexual: emasculate and bag
• B. Both: emasculate after anther dehiscence, then bag
• C. Both: no bagging needed if the stigma is receptive
• D. Bisexual: emasculate (remove anthers before dehiscence) and bag; unisexual female flowers: bagging alone, since there are no anthers to remove