Question

Part A

1.A two-point test cross is performed between two loci in an area of the genome known to have very low levels of recombination. How will this affect distances on genetic maps made in this region of the genome?

Underestimate the distances

It could under- or overestimate the distance

Overestimate the distances

It will not affect the estimation of distances

2.You perform a testcross with an individual that is known to be heterozygous but their allele arrangement is unknown. You get the following progeny:

aa bb	56
aa Bb	20
Aa bb	18
Ab Bb	62

What is the allele arrangement in the heterozygous parent?

Trans configuration; Ab/aB

Trans configuration; AB/ab

Cis configuration; AB/ab

Cis configuration; Ab/aB

Answer 1

1. A two point test cross was developed by Mendel. Here, a phenotypically dominant individual is crossed with a phenotypically recessive individual to determine the frequency of recombination. If there are very low levels of recombination, it means that the genes are more or less parental and the genes on two loci lie close to each other. Hence, it could lead to underestimation of the distances. Distances made in this region of the genome are considerably reduced.

Hence, the first option is the correct answer.