Reason for trisomy in Down's syndrome is:
1. Non-disjunction during sperm formation
2. Non-disjunction during egg formation
3. Non-disjunction at the time of egg or sperm formation
4. Addition of one extra chromosome during mitosis
Multivalent chromosome is formed by:
1. Inversion
2. Deletion
3. Reciprocal translocation
4. Point mutation
A normal leaf cell has how many genomes?
1. 1
2. 2
3. 3
4. 4
Mental retardation in man occurs due to:
1. Loss of one X chromosome
2. Addition of one X chromosome
3. Slight growth in Y
4. Overgrowth in Y
ABO blood group has:
1. Two codominant and one recessive allele
2. Two codominant and two recessive allele
3. Two incompletely dominant genes
4. Two pseudo alleles
A normal woman, whose father was colour-blind is married to a normal man. The sons would be:
1. 50% colour-blind
2. All normal
3. All colour-blind
4. 75 % colour-blind
The recessive genes located on X-chromosomes in humans are always:
1. Sub-lethal
2. Expressed in males
3. Expressed in females
4. Lethal
A male human is heterozygous for autosomal genes A and B and is also hemizygous for hemophilic gene h. What proportion of his sperm will be ABH?
1. | 1/32 | 2. | 1/16 |
3. | 1/4 | 4. | 1/8 |
A self-fertilizing trihybrid plant forms:
1. | 4 different gametes and 16 different zygotes |
2. | 8 different gametes and 16 different zygotes |
3. | 8 different gametes and 32 different zygotes |
4. | 8 different gametes and 64 different zygotes |
Lack of independent assortment of two genes A and B in the fruit fly Drosophila is due to:
1. Recombination
2. Linkage
3. Crossing over
4. Repulsion