Module: | Pre-fertilization: Micro/Megasporogenesis
Q14: Consider the following statements regarding outbreeding devices in angiosperms:
1. Dichogamy is an outbreeding device where pollen release and stigma receptivity are not synchronized.
2. Self-incompatibility is a physiological mechanism that prevents self-pollen from fertilizing the ovules.
3. The production of unisexual flowers on the same plant (monoecious plants) prevents both autogamy and geitonogamy.
Which of the above statements is/are correct?
2. Self-incompatibility is a physiological mechanism that prevents self-pollen from fertilizing the ovules.
3. The production of unisexual flowers on the same plant (monoecious plants) prevents both autogamy and geitonogamy.
Which of the above statements is/are correct?
✅ Correct Answer: A
The correct option is A. Only Statement 1 is correct.
Continuous self-pollination leads to inbreeding depression, so plants have evolved outbreeding devices.
Dichogamy is a structural timing mechanism where either the pollen is shed before the stigma is receptive (protandry) or vice versa (protogyny), preventing autogamy.
Statement 2 is incorrect because self-incompatibility is strictly defined as a genetic mechanism, not merely physiological; it involves multi-allelic recognition systems that block pollen tube growth of self-pollen.
Statement 3 is incorrect because while monoecious plants (like castor and maize) produce separate male and female flowers on the same plant, this structural arrangement prevents autogamy but cannot prevent geitonogamy, since pollen can still travel between different flowers on the exact same genetic individual.
Continuous self-pollination leads to inbreeding depression, so plants have evolved outbreeding devices.
Dichogamy is a structural timing mechanism where either the pollen is shed before the stigma is receptive (protandry) or vice versa (protogyny), preventing autogamy.
Statement 2 is incorrect because self-incompatibility is strictly defined as a genetic mechanism, not merely physiological; it involves multi-allelic recognition systems that block pollen tube growth of self-pollen.
Statement 3 is incorrect because while monoecious plants (like castor and maize) produce separate male and female flowers on the same plant, this structural arrangement prevents autogamy but cannot prevent geitonogamy, since pollen can still travel between different flowers on the exact same genetic individual.