77 exam-style questions on Cell and nuclear division — topic D2.1 of Continuity and change in the IB Biology syllabus — with answers and explanations. Samples below; the full set is free with an account.
State the phase of the cell cycle during which DNA replication occurs.
Answer: S phase
DNA is replicated during the S (synthesis) phase of interphase, producing two identical sister chromatids per chromosome before mitosis begins.
In a cell with a diploid number of 2n = 8, how many chromosomes are present in each daughter cell produced by mitosis?
Answer: 8
Mitosis is division that conserves chromosome number, so each daughter cell receives the full diploid set of 8 chromosomes.
During which stage of mitosis do the chromosomes line up along the equator of the cell?
Answer: Metaphase
In metaphase the condensed chromosomes are moved by the spindle to the equatorial plane before the sister chromatids are separated.
A cell with 2n = 6 completes meiosis. State the number of chromosomes present in each of the four resulting cells.
Answer: 3
Meiosis is a reduction division, halving the chromosome number from the diploid 6 to the haploid 3 in each gamete.
Which process during meiosis I is the main source of new combinations of alleles by the exchange of segments between homologous chromosomes?
Answer: Crossing over
Crossing over at chiasmata swaps equivalent segments between non-sister chromatids of homologues, recombining alleles that were previously linked.
The random orientation of bivalents at the metaphase plate of meiosis I generates variation. This process is best described as:
Answer: Independent assortment
Independent assortment means each homologous pair orients randomly, so maternal and paternal chromosomes are distributed to gametes in many different combinations.
That was 6 of 77 Cell and nuclear division questions.
Practise all 77 freeOutlineAO2 · 1–4 marks
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77 Cell and nuclear division questions — free with an account. Spaced repetition, streaks and full exam simulations included.
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