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Question
About 8% of the human male population suffers from colour blindness, whereas only about 0.4% of the human female population suffers from this disease. Write an explanation to show how it is possible.
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Solution
Colour blindness is a sex-linked disorder and is caused by a recessive gene located on the X chromosome. The Y chromosome of male does not carry any gene for colour vision and the defect appears in the presence of a single recessive gene (XcY). As a result, colour blindness is more common in males (8%) as compared to females (0.4%).
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Read the following and answer from given below:
Turner's syndrome is an example of monosomy. It is formed by the union of an allosome-free egg and a normal 'X' containing sperm or a normal egg and an allosome-free sperm. The individual has 2n = 45 chromosomes (44 + X0) instead of 46. Such individuals are sterile females who have rudimentary ovaries, underdeveloped breasts, small uterus, short stature, webbed neck, and abnormal intelligence. They may not menstruate or ovulate. This disorder can be treated by giving female sex hormones to women from the age of puberty to make them develop breasts and have menstruation. This makes them feel more normal.
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| Column I | Column II | ||
| i. | Thalassemia | a. | X monosomy |
| ii. | Turner’s syndrome | b. | Extra X chromosomes in male |
| iii. | Klinefelter’s syndrome | c. | 21st Trisomy |
| iv. | Down’s syndrome | d. | Mendelian disorder |
