Question

a parent cell has 5 homologous pairs of chromosomes.
during meiosis i a non - disjunction event involving one chromosome
occurs.
what is the resulting number of chromosomes in each of the 4 gametes
produced at the end of meiosis?
select one:
○ a. 5,5,5,5
○ b. 6,6,4,4
○ c. 5,5,4,4
○ d. 6,5,5,4
clear my choice

Explanation:

Step1: Determine normal chromosome count

Parent cell has 5 homologous pairs (10 total). Normal meiosis I splits homologs: each daughter cell gets 5 chromosomes. Normal meiosis II splits sister chromatids, so gametes have 5 each.

Step2: Effect of meiosis I nondisjunction

Nondisjunction in meiosis I: one pair of homologs fails to separate. So two daughter cells from meiosis I get 6 and 4 chromosomes (instead of 5 each).

Step3: Meiosis II outcome

Each meiosis I daughter cell divides in meiosis II (sister chromatids separate normally). The 6-chromosome cell produces two gametes with 6 each; the 4-chromosome cell produces two gametes with 4 each.

Answer:

b. 6,6,4,4