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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%).
RELATED QUESTIONS
Identify ‘a’, ‘b’, ‘c’, ‘d’, ‘e’ and ‘f’ in the table given below:
| S. No. | Syndrome | Cause | Characteristics of affected individuals | Sex (male/female/both) |
| 1. | Down’s | Trisomy of 21 |
‘a’ |
‘b’ |
| 2. | ‘c’ | XXY | Overall masculine development | ‘d’ |
| 3. | Turner’s | 45 with XO |
‘e’ |
‘f’ |
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A short stature with webbing of neck and low posterior hairline indicates ______ syndrome.
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If a colour-blind man marries a woman who is homozygous for normal colour vision, the probability of their son being colour-blind is ______.
The most striking example of point mutation is found in a disease called ______.
Placed below is a karyotype of a human being.
On the basis of this karyotype, which of the following conclusions can be drawn: ______
The practice of analyzing inheritance patterns in human beings is called ______
