Question

Which of the following statements is not true of two genes that show 50% recombination frequency?
A. The genes may be on different chromosomes.
B. The genes are tightly linked.
C. The genes show independent assortment.
D. If the genes are present on the same chromosome, they undergo more than one crossover in every meiosis.

Answer 1

Hint: Recombinant frequency is a frequency that has a single chromosomal crossover that will occur during meiosis between the two genes. The actual gap between the genes is a reasonable approximation.

Complete answer: The way of preparing new gene arrangements is recombination, either by crossing over or by a separate division of homologous chromosome pairs. Crossover is the genetic material exchange mechanism between two non-sister chromatids with homologous chromosomes that generate new genetic material (recombination) combinations. The crossover frequency is directly proportional to the difference between the two genes. Therefore, the greater the degree of recombination, the larger the distance between the two genes.
Therefore, choice A for these genes is also right. The higher level of recombination indicates that these genes are present far apart, even on the other hand.
-The likelihood of linkage is reduced with an increased distance, and that of independent gene assortment is increased. Therefore, genes that have a recombination level of 50 percent cannot be closely related. For these genes, choice B is not valid.
-The distantly located genes display independent assortment; for these genes, therefore, choice C is right.
-The genes present in synteny on the same chromosomes; due to demonstrable distance between the two, they may undergo multiple crossovers per meiosis. Hence, D is also correct.
Hence, the correct answer is option B- The genes are tightly linked.

Note: The British geneticist William Bateson carried out the observation of the recombination and linkage frequency. Reginald Punnett and, in 1905, Edith Rebecca Saunders. Centered on Mendel's law of inheritance in the pea farm, they carried out their experiment. Thomas Hunt Morgan performed a thorough analysis of the linkage and the genetic linkage unit is known as Centimorgan (cM) in his honour.