In which phase of the cell cycle does DNA replication take place?
- A.G1 phase
- B.S phase
- C.G2 phase
- D.M phase
Correct answer
Explanation
The correct answer is B, the S phase, also called the synthesis phase, which lies in the middle of interphase. During this phase the DNA of the cell is copied so that the amount of DNA in the nucleus doubles, while the number of chromosomes remains unchanged because each chromosome now simply consists of two identical sister chromatids joined at the centromere. In animal cells the centriole also duplicates during this phase. A, the G1 phase is the growth phase that follows the previous division, in which the cell makes RNA and proteins and grows in size but no DNA is copied. C, the G2 phase comes after replication is complete and is used to make the proteins and organelles needed for division. D, the M phase is the division itself, consisting of karyokinesis and cytokinesis, and no DNA synthesis occurs in it.
Read the full article: Cell Division: Mitosis and Meiosis Explained for Exams
Practice Questions
View allMitosis is called the equational division because
- A.it produces four daughter cells
- B.the chromosome number of the daughter cells is the same as that of the parent cell
- C.it halves the chromosome number
- D.it occurs only in reproductive cells
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In mitosis each centromere splits in anaphase and one chromatid of every chromosome goes to each pole, so the two daughter cells receive exactly the same number of chromosomes as the parent cell had, and exactly the same genetic information.
Read the full explanation →At which stage of mitosis do the chromosomes line up at the equator of the cell?
- A.Prophase
- B.Metaphase
- C.Anaphase
- D.Telophase
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In this stage the condensed chromosomes, each consisting of two sister chromatids, are moved by the spindle fibres until their centromeres lie in one plane across the middle of the cell, known as the metaphase plate or equatorial plate.
Read the full explanation →The splitting of the centromere and the movement of sister chromatids to opposite poles occurs in
- A.prophase
- B.metaphase
- C.anaphase
- D.telophase
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Once the chromosomes are aligned on the metaphase plate and every kinetochore is attached to a spindle fibre, the centromere holding the two sister chromatids together splits.
Read the full explanation →Cytokinesis in a plant cell differs from that in an animal cell because
- A.a cleavage furrow forms in the plant cell
- B.a cell plate forms in the plant cell
- C.the plant cell does not divide its cytoplasm
- D.the plant cell divides its nucleus twice
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An animal cell divides its cytoplasm by a cleavage furrow, in which the plasma membrane is pulled inward around the middle until the cell is pinched into two.
Read the full explanation →How many daughter cells are produced at the end of meiosis in one parent cell, and of what kind?
- A.Two diploid cells
- B.Two haploid cells
- C.Four haploid cells
- D.Four diploid cells
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Meiosis begins with a single round of DNA replication and is then followed by two successive nuclear divisions. Meiosis I is the reduction division, in which homologous chromosomes separate and the two cells formed already carry half the parental chromosome number.
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