Which of the following offspring genotypes could result from the fertilization of an egg that had undergone nondisjunction in meiosis II with a normal haploid sperm? (Because a nondisjunction event in meiosis II could involve the chromosome containing gene A or the chromosome containing gene a, be sure to consider both possibilities in your final answer .)

See explanation below

Explanation:

Non-disjunction occur as a result of lack of separation of homologous chromosomes during meiosis.

As a result, the gametes (the daughter cells formed) produced end up having extra or lesser chromosomes as compared to a normal gamete.

When a gamete with extra chromosome fertilizes a normal gamete, the resulting offspring will have an extra chromosome (trisomy condition).

On the other hand, when a gamete with one less chromosome than normal fertilizes a normal gamete, the resulting offspring will have one less chromosome than normal offspring (monosomy condition).

Assuming a chromosome with Aa gene undergoes non disjunction during meiosis, the resulting gametes either contain both A and a chromosome or contain no chromosome at all.

If Aa gamete is fertilized by a normal haploid sperm (a), the resulting zygote will have the genotype Aaa.

If a gamete with no chromosome at all fertilizes a normal haploid sperm, the resulting offspring will have the genotype a.