Photo AI
In fruit flies, males have the sex chromosomes XY and the females have XX - AQA - A-Level Biology - Question 4 - 2021 - Paper 2
Question 4
In fruit flies, males have the sex chromosomes XY and the females have XX. In fruit flies, a gene for eye colour is carried on the X chromosome. The allele for red e... show full transcript
Worked Solution & Example Answer:In fruit flies, males have the sex chromosomes XY and the females have XX - AQA - A-Level Biology - Question 4 - 2021 - Paper 2
Step 1
Explain why males are more likely to have white eyes.
Answer
Males have only one X chromosome; thus, they have only one allele for the eye color trait. If that allele is 'r' for white eyes, they will exhibit white eyes since there is no dominant allele to mask its effect. On the other hand, females have two X chromosomes and can be heterozygous for this trait (having one red and one white allele). This means that if a female has even one 'R' allele, she will display red eyes. Therefore, because males have only one allele, they are more likely to express recessive traits like white eyes.