NEET BIOLOGY

Detailed explanation-1: -Several genes are linked to a single chromosome, and chromosomes are the ‘particles’ separated during meiosis, not the individual alleles suggested by Mendel. Therefore, Hunt predicted not all alleles should independently assorted as predicted by Mendel. Different genes on the same chromosome should be linked.

Detailed explanation-2: -Therefore, Morgan correctly proposed that the strength of linkage between two genes depends upon the distance between the genes on the chromosome. This proposition became the basis for construction of the earliest maps of the human genome.

Detailed explanation-3: -To understand further, he performed a cross between a heterozygous red-eyed female with a white-eyed male. This gave a ratio of 1:1:1:1 in the progeny(1 white eyed female, 1 red eyed female, 1 white eyed male and 1 red eyed male). This made Morgan think about the linkage between the traits and sex chromosomes.

Detailed explanation-4: -Morgan discovered a mutation that affected fly eye color. He observed that the mutation was inherited differently by male and female flies. Based on the inheritance pattern, Morgan concluded that the eye color gene must be located on the X chromosome.

Detailed explanation-5: -When cells divide during meiosis, homologous chromosomes are randomly distributed to daughter cells, and different chromosomes segregate independently of each other. This called is called independent assortment. It results in gametes that have unique combinations of chromosomes.