SCIENCE
CELL BIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Increases sharply during the period just before
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Is at constant level during the life of the cell
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Continues to increase during mitosis
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Increases immediately after mitosis is completed
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Detailed explanation-1: -During S phase, replication increases the DNA content of the cell from 2n to 4n, so cells in S have DNA contents ranging from 2n to 4n. DNA content then remains at 4n for cells in G2 and M, decreasing to 2n after cytokinesis.
Detailed explanation-2: -False. As a cell’s size increases, the amount of DNA stays the same. The information used to build the molecules needed for cell growth is in the DNA. If a cell grows too large, an “information crisis” would occur.
Detailed explanation-3: -Before the cell undergoes mitosis, the cell must make two copies of its DNA so that each daughter cell has a complete copy of the genetic material. At the onset of mitosis the nuclear envelope dissolves, and each chromosome lines up with its copy.
Detailed explanation-4: -During interphase, the cell grows and makes a copy of its DNA. During the mitotic (M) phase, the cell separates its DNA into two sets and divides its cytoplasm, forming two new cells.