Which plant species, introduced into India as a contaminant, has become ubiquitous and is a common cause of pollen allergy?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Parthenium hysterophorus
Explanation: Parthenium or carrot grass that came into India as a contaminant with imported wheat has become ubiquitous in occurrence and causes pollen allergy.
To maintain pollen viability for crop breeding programs, pollen grains can be stored in liquid nitrogen at which temperature?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: -196 degrees C
Explanation: It is possible to store pollen grains of a large number of species for years in liquid nitrogen (-196 C). Such stored pollen can be used as pollen banks.
Which of the following represents a multicarpellary apocarpous gynoecium?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: Michelia
Explanation: The pistils may be fused together (syncarpous) (Figure 1.7b - Papaver) or may be free (apocarpous) (Figure 1.7c - Michelia).
The process of formation of megaspores from the megaspore mother cell is termed:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Megasporogenesis
Explanation: The process of formation of megaspores from the megaspore mother cell is called megasporogenesis.
In the majority of flowering plants, the embryo sac develops from a single functional megaspore. This type of development is called:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: Monosporic development
Explanation: Only the functional megaspore develops into the female gametophyte (embryo sac). This method of embryo sac formation from a single megaspore is termed monosporic development.
Which cellular structure at the micropylar tip of synergids plays an important role in guiding the pollen tubes?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: Filiform apparatus
Explanation: The synergids have special cellular thickenings at the micropylar tip called filiform apparatus, which play an important role in guiding the pollen tubes into the synergid.
Which of the following plants produces both chasmogamous (open) and cleistogamous (closed) flowers?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: A
Answer: Viola (Common pansy)
Explanation: Some plants such as Viola (common pansy), Oxalis, and Commelina produce two types of flowers – chasmogamous flowers and cleistogamous flowers.
Geitonogamy involves the transfer of pollen grains to the stigma of:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Another flower of the same plant
Explanation: Geitonogamy – Transfer of pollen grains from the anther to the stigma of another flower of the same plant.
In corn cobs, the "tassels" or "ears" waving in the wind represent which part of the flower?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: Stigma and Style
Explanation: The ears you see are nothing but the stigma and style which wave in the wind to trap pollen grains.
Pollination by water is rare in flowering plants and is limited to approximately how many genera?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: 30
Explanation: Pollination by water is quite rare in flowering plants and is limited to about 30 genera, mostly monocotyledons.