How many reduction divisions are necessary for the formation of 200 grains of wheat?

Solution

For the formation of 100 grains of wheat-100 pollen grains and 100 megaspores are required. Each - microspore mother cell produces 4 microspores (pollen grains) as aresult of reductiondivision. Hence for the formation of 100 pollen grains, ¹⁰⁰/₄= 25 PMC are needed and each will undergo one reduction division. Each megaspore mother cell will produce 4 megaspores in which one become functional and other three degenerate. Thus each MMC produces one megaspore. So 100 MMC are required to produce 100 megaspores. Total number of reduction divisions to produce 100 grains is 100 + 25= 125.

Prophase is longer in

The microtubules from opposite poles of the spindle get attached to the kine to chores of sister chromatids in

Meiosis and mitosis differ from each other because in meiosis

Solution

Four nuclei formed are not similar to parent ones because they are haploid in nature. Homologous chromosome pairs are exchange parts because in crossing over exchange of chromatid arms takes place and number of chromosomes gets halved.

Most cells divide if they receive the proper signal at a checkpoint in the _____ phase of the cell cycle.

Solution

If at G₁cells are given the signal to divide, they are unlikely to be stopped at subsequent checkpoints.

During the first metaphase of meiosis the centromeres

During cell division,sometimes there will be failure of separation of sister chromatids. This event is called

Four chromatids and two centromeres which are homologous occurs in

In meiosis, the centromere divides during

Solution

In meiosis II division is equational division; thus centromere divides and chromatid move towards the pole during anaphase-II.

At what phase of meiosis are there two cells, each with sister chromatids alignedat the spindle equator?

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