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Unit-4 Cell Cycle

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41
A. increases the number of cells
B. halves the number of cells
C. produces gametes
D. reduces chromosome number
Answer: Growth occurs by the mitotic division of somatic cells, which increases the number of cells in the body.
42
A. Meiosis
B. Mitosis
C. Fertilization
D. Apoptosis
Answer: Damaged tissues are repaired as surrounding cells divide by mitosis and replace the lost cells.
43
A. Hydra by budding
B. Flowering plants by seeds
C. Humans by fertilization
D. Birds by laying eggs
Answer: In Hydra, new individuals are produced by budding, which involves mitotic divisions of cells.
44
A. Different from the parent
B. Identical to the parent and to each other
C. Haploid
D. Half the size of the parent
Answer: Mitosis produces two genetically identical daughter cells, also called clones.
45
A. Skin cells
B. Nerve cells
C. Liver cells
D. Blood cells
Answer: Mature nerve cells (neurons) enter the G0 phase and generally do not divide.
46
A. Somatic (body) cells
B. Only gametes
C. Only germ cells
D. Only zygotes
Answer: Mitosis occurs in somatic cells, while meiosis occurs in reproductive cells.
47
A. undergo meiosis to form new cells
B. divide by mitosis to replace dead cells
C. undergo apoptosis
D. fuse to form gametes
Answer: Skin cells near the wound divide rapidly by mitosis, producing new cells that replace the damaged ones.
48
A. Apoptosis
B. Cancer
C. Fertilization
D. Gamete formation
Answer: When cell division is not properly controlled, cells divide excessively, forming tumors and leading to cancer.
49
A. halves the chromosomes
B. produces diploid daughter cells
C. reduces the chromosome number to n
D. involves two divisions
Answer: Since mitosis produces two diploid daughter cells, the chromosome number remains constant generation after generation.
50
A. Replication points
B. Checkpoints
C. Centromeres
D. Synapses
Answer: Checkpoints (such as G1/S and G2/M) monitor the cell cycle and ensure the cell divides only under proper conditions.
51
A. Equational division
B. Reductional division
C. Somatic division
D. Regenerative division
Answer: Meiosis is called reductional division because it halves the chromosome number.
52
A. Somatic cells
B. Reproductive organs (gonads)
C. Muscle cells
D. Nerve cells
Answer: Meiosis occurs in the reproductive organs where gametes are formed.
53
A. One
B. Two
C. Three
D. Four
Answer: Meiosis consists of two successive divisions: meiosis I and meiosis II.
54
A. 2
B. 4
C. 8
D. 16
Answer: One parent cell undergoing meiosis produces four haploid daughter cells.
55
A. Condensation of chromosomes
B. Synapsis and crossing over
C. Formation of spindle fibers
D. Division of the centromere
Answer: Synapsis (pairing of homologous chromosomes) and crossing over occur only in prophase I of meiosis.
56
A. Diploid
B. Haploid
C. Polyploid
D. Triploid
Answer: Meiosis halves the chromosome number, so the four daughter cells are haploid (n).
57
A. Meiosis II
B. Meiosis I
C. Interphase
D. Cytokinesis
Answer: In meiosis I, homologous chromosomes separate, reducing the chromosome number from 2n to n.
58
A. Somatic cells
B. Gametes
C. Skin cells
D. Muscle cells
Answer: Meiosis produces haploid gametes such as sperm and egg cells.
59
A. Anaphase I
B. Prophase I
C. Telophase II
D. Metaphase II
Answer: Prophase I is the longest phase of meiosis because synapsis and crossing over take place during it.
60
A. remain the same
B. double in every generation
C. become half
D. become zero
Answer: Without meiotic halving, the fusion of two gametes would double the chromosome number each generation.
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