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प्रश्न
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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उत्तर
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%).
संबंधित प्रश्न
What will be the phenotype of progeny, if a carrier haemophilic female marries a normal male?
Why are color-blindness and thalassaemia categorised as Mendelian disorders? Write the symptoms of these diseases seen in people suffering from them.
Give an example of an autosomal recessive trait in humans. Explain its pattern of inheritance with the help of a cross.
Why is pedigree analysis done in the study of human genetics? State the conclusions that can be drawn from it.
Following list indicates various genetic diseases. Identify the diseases that are not caused due to single gene defect.
Huntington's chorea, alkaptonuria, Sickle cell anaemia, Down syndrome, thalassemia, Taysachs disease, Turner syndrome, cystic fibrosis, haemophi Lia, Klinefelter syndrome, albinism
This abnormality occurs due to monosomy (2n - 1); the individual has 2n = 45 chromosomes with 44 + XO genotype.
If a father and son are both defective in red-green colour vision, is it likely that the son inherited the trait from his father? Comment.
It is said, that the harmful alleles get eliminated from population over a period of time, yet sickle cell anaemia is persisting in human population. Why?
Match the disorder in column I with their nature in column II.
| 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 |
Trisomy of 21st chromosome leads to a disorder ______.
