Pollen–Pistil Interaction — Unsolved Practice Set
Chapter: Sexual Reproduction in Flowering Plants | Topic: Pollen Pistil Interaction
POLLEN–PISTIL INTERACTION — UNSOLVED PRACTICE SET
Topic: Pollen Pistil Interaction
Multiple Choice Questions
Q1. Pollen–pistil interaction begins with:
- Fertilisation
- Recognition of pollen by the stigma
- Formation of the pollen tube in the ovary
- Fusion of gametes
Q2. The entry of the pollen tube into the ovule through the micropyle is called:
- Chalazogamy
- Mesogamy
- Porogamy
- Xenogamy
Q3. Which structure secretes chemicals that help guide the pollen tube towards the embryo sac?
- Antipodals
- Synergids
- Nucellus
- Integuments
Q4. If pollen grains landing on the stigma are recognised as incompatible, the pistil may:
- Assist immediate fertilisation
- Prevent pollen germination or pollen tube growth
- Speed up ovule formation
- Have no effect at all
Q5. The pollen tube usually carries how many male gametes at the time it enters the embryo sac?
- One
- Two
- Three
- Four
Short Answer Questions
Q6. What role does the stigma surface play in ensuring that only compatible pollen germinates?
Q7. Name the three pathways by which a pollen tube may enter the ovule, and identify the most common one.
Q8. Why is the growth of the pollen tube considered a directed/guided process rather than random growth?
Q9. What happens to one of the two synergids just before the pollen tube discharges its contents into the embryo sac?
Long Answer Questions
Q10. Describe, step by step, the journey of a pollen grain from landing on the stigma to the discharge of male gametes into the embryo sac.
Q11. Explain how a pistil is able to distinguish between compatible and incompatible pollen, and discuss the biological significance of this recognition system.
APPLICATION / ANALYSIS
Q12. In a controlled pollination experiment, pollen from a flower is placed on its own stigma, but no pollen tube growth is observed even after several hours. Suggest a possible explanation involving pollen–pistil interaction, and name the phenomenon likely responsible.
Q13. A plant breeder tries to cross two different but related plant species and finds that pollen tube growth stops midway through the style. Based on your understanding of pollen–pistil interaction, explain what this indicates about the compatibility between the two species.