SCIENCE
BOTANY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Amount of DNA doubles in each cell
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amount of DNA remains same in each cell
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Chromosomes number is increased
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amount of DNA is reduced to half in each cell.
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Detailed explanation-1: -During S phase (synthesis phase), DNA undergoes replication and makes a copy of itself. Hence, the content of DNA doubles during S phase. Each chromosome after DNA replication will have two chromatids and there is no change in the chromosome number. Hence, the chromosome number remains constant during S phase.
Detailed explanation-2: -During S phase, DNA synthesis or replication takes place. In this time the amount of DNA per cell doubles. However, there is no increase in the chromosome number and the chromosome number remains same. Hence, the amount of DNA and number of chromosomes after S phase will be 4C and 2n respectively.
Detailed explanation-3: -A cell cycle is divided into G1, S, G2 and M phases. G1 or first growth is followed by S phase or synthesis phase. DNA replication occurs in S phase and DNA amount doubles up, i.e., a cell with 2C DNA in G1 phase will now have 4C DNA.
Detailed explanation-4: -In S phase, the cell synthesizes a complete copy of the DNA in its nucleus. It also duplicates a microtubule-organizing structure called the centrosome. The centrosomes help separate DNA during M phase.