Question

Which one is the wrong statement in a cross
$\frac { b+ }{ a+ } \times \frac { ab }{ ab }$
(A)The progeny obtained with genotype $\frac { ab }{ ab }$ is a parental type
(B)The progeny with $\frac { ++ }{ ab }$ is recombination type
(C)The distance of two genes can be calculated from the percentage of progeny with genotype $\frac { ab }{ ab }$
(D)Percentage of parental type of progenies can be calculated from the percentage of progeny with $\frac { ab }{ ab }$

Answer 1

Hint: It is the exchange of genetic material during sexual reproduction between two homologous chromosomes' non-sister chromatids that results in recombinant chromosomes. It generally happens while the coordinating region on coordinating chromosomes break then reconnect to the contrary chromosome.

Complete answer:
In the given problem, one parent is having genotype $\frac { b+ }{ a+ }$ and another parent is having a genotype $\frac { ab }{ ab }$. The gametes obtained from the first parent will be ab, ++, +b, and a+. The gametes obtained from the second parent will be ab. When a cross is made between these parents, the progeny will have genotype $\frac { ab }{ ab }$, $\frac { b+ }{ a+ }$, $\frac { a+ }{ ab }$, and $\frac { ab }{ +b }$. The parental type progeny obtained with genotype ab/ab and +b/a+ are. Progeny obtained with genotypes $\frac { a+ }{ ab }$ and $\frac { ab }{ +b }$ are recombination types.

Additional information:
There are two well known and overlapping hypotheses that clarify the origin of the traverse, coming from the various speculations on the starting point of meiosis. The main hypothesis settles upon the idea that meiosis developed as another technique for DNA repair, and in this manner, crossing-over might be novel gratitude to supplanting potentially damaged areas of DNA. The second hypothesis comes from the possibility that meiosis advanced from the bacterial change, with the capacity of spreading variety.

So the correct answer is ‘The progeny with $\frac { ++ }{ ab }$ is recombination type’.

Note: Recombination brings about another course of action of maternal and paternal alleles on a similar chromosome. Although equivalent genes appear within the same order, some alleles are different. In this way, it's theoretically possible to possess any combination of parental alleles in an offspring, and therefore the incontrovertible fact that two alleles appear together in one offspring does not have any influence on the statistical probability that another offspring will have an equivalent combination.