Which of the following is the main reason why meiosis is important for sexually reproducing organisms?
- A.It repairs damaged tissues
- B.It keeps the chromosome number constant across generations and creates genetic variation
- C.It allows cells to grow larger
- D.It produces identical copies of the parent cell
Correct answer
Explanation
The correct answer is B. If gametes carried the full chromosome number, fertilisation would double it in every generation. Meiosis halves the number when gametes are formed, so that the union of two gametes restores the original diploid number and keeps it constant from one generation to the next. At the same time, crossing over in pachytene and the independent assortment of maternal and paternal chromosomes in metaphase I shuffle the genes, so no two gametes are alike and the offspring differ from both parents and from each other. A describes a function of mitosis. C is wrong because growth in size is a feature of interphase, not of meiosis. D is wrong because identical copies are exactly what meiosis avoids producing; that is the result of mitosis.
Read the full article: Cell Division: Mitosis and Meiosis Explained for Exams
Practice Questions
View allIn which phase of the cell cycle does DNA replication take place?
- A.G1 phase
- B.S phase
- C.G2 phase
- D.M phase
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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.
Read the full explanation →Mitosis 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.
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