Question

Which of the following is true regarding female Drosophila?

• A. It shows very low recombination
• B. It shows very high recombination
• C. It shows no recombination at all
• D. Only parental combinations are observed

Answer 1

The correct option is A It shows very low recombination

Recombination refers to the appearance of new allelic combinations in the gametes when the homologous chromosomes in the parents undergo crossing over to exchange genetic material between the segments of non-sister chromatids of homologous chromosomes.
In the case of female Drosophila, it shows recombination although it is very low. Complete absence of recombination is usually not seen in female Drosophila, although it can be seen in male Drosophila.
Without crossing over, there is no recombination. Crossing over generally takes place between homologous chromosomes. But in male Drosophila, the X and Y chromosomes are morphologically different and far from being homologous. So, this pair might not undergo crossing over and hence recombination won’t be seen.
Female Drosophila doesn’t show very high recombination. The recombinant types are usually less than 25% of the total.
Further in female Drosophila, apart from parental combinations, recombinant allelic formation is also seen.