What role does nondisjunction play in the formation of a fertile allopolyploid hybrid?

• A. It ensures that only parental chromosomes are inherited, maintaining species integrity.
• B. It prevents the fusion of gametes from different species.
• C. It leads to the loss of chromosomes, resulting in sterile hybrids.
• D. It causes chromosome doubling, allowing homologous chromosomes from different species to pair during meiosis.

Answer: (D)

Verified step by step guidance

1. Understand that nondisjunction is the failure of chromosome pairs to separate properly during cell division, which can lead to changes in chromosome number.
2. Recognize that in the context of allopolyploid hybrids, nondisjunction can cause chromosome doubling, meaning the hybrid ends up with two complete sets of chromosomes from each parent species.
3. Know that this chromosome doubling is crucial because it allows homologous chromosomes from each species to find a pairing partner during meiosis, which is necessary for fertility.
4. Realize that without nondisjunction and the resulting chromosome doubling, the hybrid would have unpaired chromosomes during meiosis, leading to sterility due to improper segregation.
5. Conclude that nondisjunction facilitates the formation of fertile allopolyploid hybrids by enabling proper chromosome pairing and segregation during meiosis.