Outbreeding Devices — Unsolved Practice Set
Chapter: Sexual Reproduction in Flowering Plants | Topic: Outbreeding Devices
OUTBREEDING DEVICES — UNSOLVED PRACTICE SET
Topic: Outbreeding Devices
Multiple Choice Questions
Q1. The genetic mechanism that prevents self-pollen (or pollen from genetically similar plants) from fertilising the same flower is called:
- Dichogamy
- Herkogamy
- Self-incompatibility
- Monoecy
Q2. When the anthers and stigma of a bisexual flower mature at different times to prevent self-pollination, it is termed:
- Herkogamy
- Dichogamy
- Xenogamy
- Cleistogamy
Q3. Papaya, which bears male and female flowers on different plants, is an example of a:
- Monoecious plant
- Dioecious plant
- Hermaphrodite plant
- Cleistogamous plant
Q4. In protandrous flowers:
- Stigma matures before anthers
- Anthers mature before stigma
- Both mature simultaneously
- Neither matures
Q5. Herkogamy prevents self-pollination by:
- Producing anthers before stigma
- Physically separating anthers and stigma within a flower
- Delaying flowering
- Making flowers unisexual
Short Answer Questions
Q6. Why does continued self-pollination over many generations reduce the vigour and fertility of a plant?
Q7. Differentiate between monoecious and dioecious plants, giving one example of each.
Q8. What is self-incompatibility? How does it prevent zygote formation even after self-pollen lands on the stigma?
Q9. Give one example each of protandry and protogyny in flowering plants.
Long Answer Questions
Q10. Discuss any three outbreeding devices evolved by flowering plants to discourage self-pollination and encourage cross-pollination.
Q11. Explain why unisexuality (dioecy) is considered the most effective outbreeding device, and mention one drawback that dioecious plants face compared to bisexual plants.
APPLICATION / ANALYSIS
Q12. A plant breeder wants to develop a new hybrid variety by cross-pollinating two closely related bisexual varieties, but finds that self-pollination keeps occurring within each flower before he can intervene. Suggest which outbreeding device, if naturally present, would have made his job easier, and explain why.
Q13. In a bisexual flower where the anthers and stigma mature at exactly the same time and are positioned very close together, predict which type of pollination is most likely to dominate. Name one other phenomenon that could still prevent seed set from self-pollen even in this situation.