Question

In beetles, the gene for color and the gene for pattern are located on the same chromosome and exhibit recombination. The lined pattern allele (l) is recessive to the solid unpatterned allele (L), and the aqua color allele (b) is recessive to the blue color allele (B). Geneticists cross a homozygous lined aqua beetle with a homozygous solid blue beetle. Then, they carry out a testcross using the F1 progeny. The parental chromosomes for the testcross are given. Identify all possible gametic haplotypes each parent can form.

Answer 1

Answer and Explanation: First cross is between homozygous: LLBB x llbb.

Homozygous individuals produce one type of gamete:

• For homozygous dominant is LB
• For homozygous recessive is lb

So, F1 progeny will have genotype : LlBb

Second cross is between the F1 progeny in a testcross. A testcross is a genetic cross between a homozygous recessive individual and a suspective heterozygous genotype to determine the latter.

So, second cross is: LlBb x llbb

As said before, homozygous will produce only one type of gamete: lb

For heterozygous individuals, and one that exhibits recombination, will produce 4 types of gametes:

• LB : parental
• lb : parental
• Lb : recombinant
• lB : recombinant

Answer 2

Answer:

b) is recessive to the blue color allele

Explanation: