Question

Complete linkage is found in
(A) Birds
(B) Snakes
(C) Female drosophila
(D) Male drosophila

Answer 1

Hint: Complete linkage is found in organisms that are also known as small fruit flies. In fruit fly also it is present only in one sex which has rounded genitalia at the tip of their abdomen.

Complete step by step answer:
- The arrangement of genes or the sequences of the DNA on the same chromosomes together and close is called linkage.
- Complete linkage is found in Male drosophila. Male drosophila is generally smaller than the female drosophila.

- If there is a complete linkage present, the chances of crossing over reduce to a minimum or do not take place just because of the arrangement or position of alleles.
So, the correct answer is ‘Male drosophila '.

Additional Information: Complete linkage is defined as the state within which two loci are so close that alleles of those loci are virtually not possible to be separated during crossing over. In the case of male Drosophila, there's the complete absence of recombinant types because of the absence of crossover. This suggests that every one of the genes that start out on one chromosome, will find themselves thereon on the same chromosome in their original configuration. When there is the absence of recombination, only parental phenotypes are expected. The chances of two genes to get separated during crossing over depends on the physical location of the two genes. If genes are closer than there is less chance of separation after crossing over. The genome of D. melanogaster contains four pairs of chromosomes which are, X/Y pair, and three autosomes labeled 2, 3, and 4. The fourth chromosome is so tiny, it's often ignored, apart from its important eyeless gene.

Note: Both male and feminine D. melanogaster fly act polygamously which means having multiple sexual partners at a similar time. In both males and females, polygamy leads to a decrease in evening activity compared to virgin flies, more so in males than females.