Question

Assume that investigators crossed a strain of flies carrying the dominant eye mutation Lobe on the second

chromosome with a strain homozygous for the second chromosome recessive mutations smooth abdomen and
straw body. The F1 Lobe females were then backcrossed with homozygous smooth abdomen, straw body males, and
the following phenotypes were observed:
smooth abdomen, straw body 820
Lobe 780
smooth abdomen, Lobe 42
straw body 58
smooth abdomen 148
Lobe, straw body 152
What is the coefficient of coincidence?
A) 0.75 B) zero C) 0.25 D) 0.33 E) 0.5

Answer 1

The coefficient of coincidence measures recombination frequency and is calculated by dividing the observed number of double crossovers by the expected number. In this case, the coefficient of coincidence is approximately 0.20. The correct answer is c).

Step-by-step explanation:

The coefficient of coincidence is a measure of recombination frequency between two genes. It is calculated by dividing the observed number of double crossovers (DCOs) by the expected number of DCOs. In this case, the observed number of DCOs is 42 and the expected number is 58 + 148 = 206. Therefore, the coefficient of coincidence is 42/206 = 0.204. This is approximately equal to 0.20, which is option C) 0.25.