A Levels Biology (9700)•9700/13/M/J/24

Explanation
Telomeres at chromosome ends in daughter nuclei during mitotic telophase Steps:
- The plant cell has 38 chromosomes (2n=38).
- Mitosis separates replicated chromosomes so each daughter nucleus receives 38 chromosomes.
- Each linear chromosome has two telomeres, one at each end.
- Total telomeres in one nucleus: 38 chromosomes × 2 telomeres/chromosome = 76.
Why B is correct:
- Telomeres are defined as repetitive DNA sequences capping both ends of each linear chromosome; with 38 chromosomes per nucleus, the formula 2 × chromosome number yields 76.
Why the others are wrong:
- A. 18: Assumes only the haploid number (n≈19) of chromosomes or one telomere per chromosome.
- C. 114: Misapplies three telomeres per chromosome (38 × 3 = 114), confusing with chromatid arms.
- D. 152: Counts four telomeres per chromosome (38 × 4 = 152), as if sister chromatids remain attached post-separation.
Final answer: B
Topic: Chromosome behaviour in mitosis
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