Question

a human cell in g1 has 46 chromosomes. how many chromosomes does it have after s phase?
23
92
46
question 2
the majority of the bodys cell types undergo:
meiosis
mitosis
question 3
a cell that has undergone s phase:
has duplicated its chromosomes
has doubled the number of chromosomes

Explanation:

• Question 1: During the S - phase of the cell cycle, DNA replication occurs. However, the number of chromosomes does not double. Each chromosome consists of one chromatid in G1, and after S - phase, each chromosome consists of two sister chromatids attached at the centromere. But the count of chromosomes (based on the number of centromeres) remains the same. A human cell in G1 has 46 chromosomes, and after S - phase, it still has 46 chromosomes.
• Question 2: Mitosis is the process by which somatic (body) cells divide. It results in two daughter cells that are genetically identical to the parent cell. Meiosis is a specialized form of cell division that occurs in germ cells (to produce gametes) and results in cells with half the number of chromosomes. Since most body cells are somatic cells, the majority of the body's cell types undergo mitosis.
• Question 3: In the S - phase, DNA replication takes place. Each chromosome (which was a single - stranded DNA molecule in G1) is replicated. So, each chromosome now has two sister chromatids (duplicated chromosome). But the number of chromosomes (based on centromere count) does not double. For example, if there were \(n\) chromosomes in G1, after S - phase, there are still \(n\) chromosomes, but each chromosome has two chromatids.

Answer:

• Question 1: 46
• Question 2: mitosis
• Question 3: has duplicated its chromosomes