Question

Which of the following is true of a disease that is caused by a single gene found on the X chromosome of the sex chromosomes in humans?

1. Males inherit these diseases more often than females because they have only one X chromosome in the pair of sex chromosomes.

2. Males and females inherit these diseases at an equal rate, gender does not influence the DNA.

3. Females inherit these diseases twice as often as males, because they have two X chromosomes in the pair of sex chromosomes.

4. All of the choices are correct.

Answer 1

Answer :correct option is (1).

Disease that is caused by a single gene found on the X chromosome of the sex chromosomes in humans is known as X-linked disorder.Males inherit these diseases more often than females because they have only one X chromosome in the pair of sex chromosomes. X linked disorders can be recessive or dominant. In Recessive X-linked disorder female can be diseased only when both x chromosome have mutation. In case of one x chromosome having mutation will result  the female as disease carrier. While in male there is  only one x chromosome in sex chromosome. If x chromosome in male have mutation then male will be diseased.

In x linked dominant disorders both male and female would be diseased if mutation in anyone of  x chromosome occur but symptoms of disease is worse in male.

So correct option is (1).

Option 2 &3 are not correct according to given explanation. Males and females does not inherit these diseases at an equal rate, gender does influence the DNA.