Chapter 177 of 2363 min read
Flower structure, microsporogenesis and megasporogenesis
Why this is asked: Microsporogenesis and megasporogenesis are not symmetric: meiosis in the microspore mother cell gives four functional pollen grains, but meiosis in the megaspore mother cell gives four megaspores of which normally only one — usually the chalazal one — survives to form the embryo sac.
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- •Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Cells of the tapetum possess dense cytoplasm and generally have more than one nucleus. Reason (R): The presence of more than one nucleus in the tapetum increases the efficiency of nourishing the developing microspore mother cells. In the light of the above statements, choose the most appropriate answer from the options given below:
- •How many meiotic and mitotic divisions need to occur for the development of a mature female gametophyte from the megaspore mother cell in an angiosperm plant?
- •Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): A typical unfertilised angiosperm embryo sac at maturity is 8-nucleate and 7-celled. Reason (R): The egg apparatus has 2 polar nuclei. In the light of the above statements, choose the correct answer from the options given below:
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