The cells of the ovary of a wheat flower have 42 chromosomes. A macrospore is formed in the ovule by meiosis, and then its nucleus is mitotically divided, and then this process is repeated for the daughter nuclei two more times synchronously. How many chromosomes will there be in the macrospore nucleus before and after mitosis? How many nuclei are formed after three mitotic divisions?
In somatic cells of the ovary there are 42 chromosomes (2n). Spores are formed by meiosis, during which the number of chromosomes is halved. This means that in the nucleus of the macrospore after meiosis there are 21 chromosomes (1n). During mitosis, changes in the number of chromosomes in cells do not occur, that is, 21 chromosomes remain in the nuclei. And since the cell has divided mitosis three times, then 23 = 8 nuclei are formed.
Answer: 21; 21; eight.
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