Principles of Inheritance and Variation Test - 14

In birds male contain a pair of Z chromosome as sex chromosome besides autosomes while female contain one Z and one W chromosome.

Linkage is the physical association of two genes present on same chromosome. Genes located close to each other have high linkage percentage.

Male heterogamety is present in mammals in which male gametes are of two types half containing X-chromosome and half containing Y-chromosome. This condition is called male heterogamety.

Alfred Sturtevant used the frequency of recombination between genes on same chromosome as measure of the distance between genes and mapped their position. This technique is used in genetic mapping.

In our society, female are blamed for producing female children due to false notation. Although, male sperm decide the sex of the baby during fertilization.

In birds, female has been designed to be the Z and W chromosomes. In these organism female have one Z and one W chromosome and male have a pair of Z chromosome.

Two genes p and q showing 1.3% of recombination while other two genes x and y show 37.2 percent of recombination. p and q genes are present close to each other as they show less recombination percentage.

In human beings, 23 pairs of chromosomes are present in diploid cells.
Twenty two pairs of chromosomes are equal in male and female but a pair sex chromosome is different in them. Male contain XY and female contain XX sex chromosome.

In some insects, XO type of sex determination is found in which some sperms bears X-chromosome where as some do not. Numbers of male and female chromosomes are not equal. An egg fertilized by sperms having X-chromosome becomes female.