Question

A gametocyte goes through the process of meiosis and results in fertilized eggs that are normal diploid, trisomic and monosomic in the gametes that were produced. It's possible that this has occurred due to:

a) An incorrect separation of homologous chromosomes in meiosis I

b) An incorrect separation of homologous chromosomes in meiosis II

c) An incorrect separation of sister chromatids in meiosis I

d) An incorrect separation of sister chromatids in meiosis II.

Answer 1

d) an incorrect separation of sister chromatids in meiosis II

incorrect separation occurs due to non-disjunction i.e, failure of chromosome pairs to separate properly during meiosis resulting in aneuploidy (an imbalance caused due to abnormal number of chromosomes in a cell).non-disjunction mostly occurs during the anaphase when the chromosomes fail to segregate on the spindle fibres and are directed to the opposite poles.

for a) When an incorrect separation of homologous chromosomes in meiosis I occurs it results in trisomic and monosomic gametes only.No diploid gametes are formed in this case.

b) and c) donot occur

d) When an incorrect separation of sister chromatids in meiosis II occurs it results in diploid(normal),trisomic and monosomic gametes.