Which of the following observations helped Darwin shape his concept of descent with modification?
1 answer:
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Answer:
b: 8;8
Explanation:
Mitotic or meiotic cell division constitute the m phase of the cell cycle. At the end of the m phase, the new cells enter the interphase stage of the cell cycle. The interphase is further sub-divided into;
- <em>the
phase,</em>
- <em>the
phase,</em>
- <em>the S phase; and</em>
- <em>the
phase</em>.
The phase is essentially a resting phase. Cells that do not need to divide except when necessary move into this phase after exiting the m phase.
Actively dividing cells enter the phase after exiting the m phase. Cell development and growth takes place. From there, the cells enter the S phase where DNA replication/synthesis takes place. The cells then enter the
phase where proteins are synthesized in preparation for division or m phase.
At the S phase, the amount of DNA a cell carries is doubled but the chromosome number remains the same. For example, if a cell enters the S phase with 2 g of DNA containing 10 chromosomes, at the end of S phase, the amount of DNA would have come 4 g while the number of chromosomes will remain 10.
Hence, if the average amount of DNA in the assayed cells immediately after mitosis is 4 picograms, the amount would be 8 picograms at the end of S phase and will still remains 8 picograms at the end of phase.
The correct option is b.