PATHOLOGY

PATHOLOGY MCQ

GENETICS AND DISEASE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
In fruit flies, the allele for white eyes (W) is dominant to the allele for red eyes (w). Two heterozygous fruit flies are crossed, resulting in many offspring. Which of the following would best describe the population of offspring?
A
All of the offspring population is white-eyed.
B
The majority of the offspring population is red-eyed
C
The majority of the offspring population is white-eyed.
D
About half of the offspring population is red-eyed, and the other half of the population is white-eyed.
Explanation: 

Detailed explanation-1: -Example 1: In fruit flies, the gene for red eyes is dominant over the gene for white eyes. The trait is sex-linked on the X chromosome. Cross a homozygous, red-eyed female with a white-eyed male.

Detailed explanation-2: -In Drosophila, white eye colour is recessive X-linked trait while red eye colour is dominant.

Detailed explanation-3: -So the correct option is ‘3:1’.

Detailed explanation-4: -The only way an offspring can have white eyes, is if it inherited a recessive allele from both parents. The gene for eye color in fruit flies is actually sex-linked on the X-chromosome. The Punnet square below represents a cross between a heterozygous red-eyed female and a white-eyed male.

There is 1 question to complete.