3 free questions from this chapter (the full set has 30). Marking: +4 for correct · −1 for incorrect · 0 for unattempted.
Question 1Level 3 · AdvancedSingle correct
Consider the following statements about the duration of the cell cycle.
(i) Human cells in culture divide once in approximately every 24 hours.
(ii) Yeast can progress through the cell cycle in only about 90 minutes.
(iii) In the 24-hour cycle of a human cell, cell division proper lasts for only about an hour.
(iv) Interphase lasts more than 95 per cent of the duration of the cell cycle.
(v) The duration of the cell cycle is the same in all organisms and cell types.
How many statements are correct?
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Answer: A
(i), (ii), (iii) are NCERT figures. (iv) is consistent with them: 1 hour out of 24 hours is about 4.2 per cent, so interphase occupies more than 95 per cent, exactly as NCERT states. (v) is incorrect: NCERT says the duration of the cell cycle can vary from organism to organism and also from cell type to cell type, as the yeast (90 min) versus human (24 h) contrast itself shows. Hence 4 are correct. Trap: students often doubt (iv), thinking M phase is a large part of the cycle.
Exam pattern: NEET – statement counting on cell cycle phases and durationQuestion 2Level 2 · ExamSingle correct
Consider the following statements about the cell cycle as a whole.
(i) Cell growth, in terms of cytoplasmic increase, is a continuous process.
(ii) DNA synthesis takes place throughout interphase.
(iii) The events of the cell cycle are themselves under genetic control.
(iv) M phase starts with karyokinesis and usually ends with cytokinesis.
(v) Cytokinesis always follows karyokinesis in all organisms.
How many statements are correct?
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Answer: D
(i) Correct: NCERT says cell growth in terms of cytoplasmic increase is continuous. (ii) Incorrect: DNA synthesis occurs only during one specific stage (S phase) of the cell cycle. (iii) Correct: these events are under genetic control. (iv) Correct: M phase starts with nuclear division (karyokinesis) and usually ends with division of cytoplasm (cytokinesis). (v) Incorrect: the word 'usually' in (iv) matters; in some organisms karyokinesis is not followed by cytokinesis, giving a multinucleate condition. Hence 3 are correct.
Exam pattern: NEET – statement counting on basic features of cell cycleQuestion 3Level 3 · AdvancedSingle correct
A diploid meiocyte in G1 contains 12 pg of DNA in its nucleus. What will be the DNA content of (i) the nucleus of this cell in G2, (ii) each cell at prophase II, and (iii) each of the four cells formed at the end of meiosis II, respectively?
A24 pg, 12 pg, 6 pg
B24 pg, 6 pg, 3 pg
C12 pg, 6 pg, 3 pg
D24 pg, 24 pg, 12 pg
Show answer and solution
Answer: A
G1 diploid DNA = 2C = 12 pg, so C = 6 pg. S phase doubles DNA from 2C to 4C, so G2 = 24 pg. Meiosis I separates homologues; each cell after telophase I and cytokinesis has 2C = 12 pg, and since there is no DNA replication in interkinesis, prophase II also has 12 pg. Meiosis II separates sister chromatids, so each of the four products has C = 6 pg. Answer: 24, 12, 6. Option C ignores the S-phase doubling; option B halves at the wrong points; option D assumes the content stays 4C until after meiosis I.
Exam pattern: NEET – DNA content (C-value) at different stages of meiosis