In Drosophila the XXY condition leads to femaleness whereas in human beings the same condition leads to Klinefelter's syndrome in males. It proves:
1. | In human beings, the Y chromosome is active in sex determination. |
2. | Y chromosome is active in sex determination in both human beings and Drosophila. |
3. | In Drosophila Y-chromosome decides femaleness. |
4. | The Y chromosome of man has genes for the syndrome. |
Most of the mutations are:
1. Harmful
2. Harmful and recessive
3. Beneficial
4. Dominant
Down's syndrome is caused by an extra copy of chromosome number 21. What percentage of offspring produced by an affected mother and a normal father would be affected by this disorder:
1. 100%
2. 75%
3. 50%
4. 25%
Which of the following discoveries resulted in a Nobel Prize:
1. X-rays induce sex-linked recessive lethal mutations
2. Cytoplasmic inheritance
3. Recombination of linked genes
4. Genetic engineering
The linkage map of the X-chromosome of fruitfly has 66 units, with yellow body gene (y) at one end and bobbed hair (b) gene at the other end. The recombination frequency between these two genes (y and b) should be:
1. 60%
2. > 50%
3. ≤ 50%
4. 100%
Two crosses between the same pair of genotypes or phenotypes in which the sources of the gametes are reversed in one cross is known as:
1. Test cross
2. Reciprocal cross
3. Dihybrid cross
4. Reverse cross
The genes controlling the seven pea characters studied by Mendel are now known to be located on how many different chromosomes:
1. Seven
2. Six
3. Five
4. Four
Which one of the following traits of garden peas studied by Mendel was a recessive feature?
1. | Axial flower position |
2. | Green seed colour |
3. | Green pod colour |
4. | Round seed shape |
Which one of the following conditions, though harmful in itself, is also a potential saviour from a mosquito-borne infectious disease?
1. | Thalassaemia | 2. | Sickle cell anaemia |
3. | Pernicious anaemia | 4. | Leukemia |
Pattern baldness, moustaches, and beard in human males are examples of:
1. Sex-linked traits
2. Sex-limited traits
3. Sex-differentiating traits
4. Sex-determining traits