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Question
Female gametophyte of a typical dicot at the time of fertilization is
Female gametophyte of a typical dicot at the time of fertilization is
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Solution
The correct option is B 7 celled
In dicots, at the time of fertilization the female gametophyte develops from a single megaspore. This megaspore undergoes three successive mitotic divisions to form eight nucleated embryo sac. Two nuclei are formed in the first mitotic division in the megaspore. The two nuclei move to opposite poles. These nuclei divide and re-divide at their ends to form eight nucleated stage. Each end has four nuclei. Three nuclei differentiate into two synergids and one egg cell at the micropylar end. At the chalazal end, three nuclei differentiate as antipodal cells. The remaining two cells, one of the micropylar end and other at the chalazal end migrate towards the center and fuse. Hence, female gametophyte of angiosperm is 7 celled and 8 nucleated structure. Thus, the correct answer is option B.
In dicots, at the time of fertilization the female gametophyte develops from a single megaspore. This megaspore undergoes three successive mitotic divisions to form eight nucleated embryo sac. Two nuclei are formed in the first mitotic division in the megaspore. The two nuclei move to opposite poles. These nuclei divide and re-divide at their ends to form eight nucleated stage. Each end has four nuclei. Three nuclei differentiate into two synergids and one egg cell at the micropylar end. At the chalazal end, three nuclei differentiate as antipodal cells. The remaining two cells, one of the micropylar end and other at the chalazal end migrate towards the center and fuse. Hence, female gametophyte of angiosperm is 7 celled and 8 nucleated structure.
Thus, the correct answer is option B.
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