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501 questions in this collection · Page 32 of 51
Question 311 of 501
📘 CLASS XII
Sexual Reproduction In Flowering Plants
Which plant species, introduced into India as a contaminant, has become ubiquitous and is a common cause of pollen allergy?
Parthenium or carrot grass that came into India as a contaminant with imported wheat has become ubiquitous in occurrence and causes pollen allergy.
Question 312 of 501
📘 CLASS XII
Sexual Reproduction In Flowering Plants
To maintain pollen viability for crop breeding programs, pollen grains can be stored in liquid nitrogen at which temperature?
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.
Question 313 of 501
📘 CLASS XII
Sexual Reproduction In Flowering Plants
Which of the following represents a multicarpellary apocarpous gynoecium?
The pistils may be fused together (syncarpous) (Figure 1.7b - Papaver) or may be free (apocarpous) (Figure 1.7c - Michelia).
Question 314 of 501
📘 CLASS XII
Sexual Reproduction In Flowering Plants
The process of formation of megaspores from the megaspore mother cell is termed:
The process of formation of megaspores from the megaspore mother cell is called megasporogenesis.
Question 315 of 501
📘 CLASS XII
Sexual Reproduction In Flowering Plants
In the majority of flowering plants, the embryo sac develops from a single functional megaspore. This type of development is called:
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.
Question 316 of 501
📘 CLASS XII
Sexual Reproduction In Flowering Plants
Which cellular structure at the micropylar tip of synergids plays an important role in guiding the pollen tubes?
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.
Question 317 of 501
📘 CLASS XII
Sexual Reproduction In Flowering Plants
Which of the following plants produces both chasmogamous (open) and cleistogamous (closed) flowers?
Some plants such as Viola (common pansy), Oxalis, and Commelina produce two types of flowers – chasmogamous flowers and cleistogamous flowers.
Question 318 of 501
📘 CLASS XII
Sexual Reproduction In Flowering Plants
Geitonogamy involves the transfer of pollen grains to the stigma of:
Geitonogamy – Transfer of pollen grains from the anther to the stigma of another flower of the same plant.
Question 319 of 501
📘 CLASS XII
Sexual Reproduction In Flowering Plants
In corn cobs, the "tassels" or "ears" waving in the wind represent which part of the flower?
The ears you see are nothing but the stigma and style which wave in the wind to trap pollen grains.
Question 320 of 501
📘 CLASS XII
Sexual Reproduction In Flowering Plants
Pollination by water is rare in flowering plants and is limited to approximately how many genera?
Pollination by water is quite rare in flowering plants and is limited to about 30 genera, mostly monocotyledons.