Autogamy refers to pollination achieved within the same flower. Which condition is essential for autogamy to be successful?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Pollen release and stigma receptivity must be synchronized.
Explanation: Autogamy requires synchrony in pollen release and stigma receptivity and also, the anthers and the stigma should lie close to each other.
Which of the following plants produce both chasmogamous (open) and cleistogamous (closed) flowers?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: D
Answer: All of the above
Explanation: Plants such as Viola (common pansy), Oxalis, and Commelina produce two types of flowers: chasmogamous and cleistogamous.
What is a significant advantage of cleistogamy for a plant?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: It produces assured seed-set even in the absence of pollinators.
Explanation: Cleistogamous flowers are invariably autogamous as there is no chance of cross-pollen landing on the stigma. They produce assured seed-set even in the absence of pollinators.
Geitonogamy is genetically similar to autogamy because:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: The pollen grains come from the same plant.
Explanation: Geitonogamy is functionally cross-pollination involving a pollinating agent, but genetically it is similar to autogamy since the pollen grains come from the same plant.
Which type of pollination guarantees the introduction of genetically different types of pollen grains to the stigma?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: Xenogamy
Explanation: Xenogamy involves the transfer of pollen grains from the anther to the stigma of a different plant. This is the only type of pollination which brings genetically different types of pollen grains to the stigma.
Wind-pollinated flowers are characterized by which of the following features?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: Light, non-sticky pollen and well-exposed stamens.
Explanation: Wind pollination requires that pollen grains are light and non-sticky. Flowers often possess well-exposed stamens and large feathery stigma.
In the context of wind pollination, what do the "tassels" or "ears" of a corn cob represent?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: The stigma and style waving in the wind.
Explanation: The ears (tassels) of the corn cob are nothing but the stigma and style which wave in the wind to trap pollen grains.
Pollination by water is rare in flowering plants. Which set of plants represents examples of water-pollinated species?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Vallisneria, Hydrilla, Zostera
Explanation: Some examples of water pollinated plants are Vallisneria and Hydrilla (fresh water) and Zostera (marine seagrass). Water hyacinth and Water lily are insect/wind pollinated.
How does pollination occur in Vallisneria?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Female flowers reach the surface by long stalks; pollen is released on the surface.
Explanation: In Vallisneria, the female flower reaches the surface of water by the long stalk and the male flowers or pollen grains are released on to the surface of water.
In seagrasses like Zostera, how is pollination achieved?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Female flowers remain submerged and pollen is released inside the water.
Explanation: In seagrasses, female flowers remain submerged in water and the pollen grains are released inside the water. Pollen grains are long, ribbon-like and carried passively.