Q. No.Genes that code for a pair of contrasting traits or slightly different forms of the same gene are known as:
1.
Alleles
2.
Loci
3.
Cistrons
4.
Introns
What is the mode of inheritance of phenylketonuria?
| 1. | Autosomal recessive | 2. | Autosomal dominant |
| 3. | Sex linked recessive | 4. | Sex linked dominant |
Which of the following is not a feature of Down’s Syndrome?
| 1. | It is caused by a non-disjunction in an autosome. |
| 2. | The affected individual has a trisomy of chromosome 21. |
| 3. | The affected individual has a characteristic simian palmar crease. |
| 4. | The mental development of the affected individual is normal. |
What is F2 phenotypic ratio in a dihybrid cross?
| 1. | 1 : 1 | 2. | 3 : 1 |
| 3. | 9 : 3 : 3 : 1 | 4. | 1 : 1 : 1: 1 |
The expression of only one of the parental characters in a monohybrid cross in the F1, the expression of both in the F2 and the proportion of 3:1 obtained at the F2 can be explained by:
1. Law of Dominance
2. Law of segregation
3. Law of Independent Assortment
4. Two-factor interaction
When there is a change in the chromosome number such that the changes number is not an exact multiple of base number [haploid number], the condition is called as:
| 1. | Euploidy | 2. | Aneuploidy |
| 3. | Aberration | 4. | Non-disjunction |
Mutations that arise due to changes in a single base pair of DNA are called as:
| 1. | Chromosomal aberrations | 2. | Point mutations |
| 3. | Nonsense mutations | 4. | Frameshift mutations |
When Morgan hybridised yellow-bodied, white-eyed females to brown-bodied, red-eyed males and intercrossed their F1 progeny, the F2 ratio deviated very significantly from the 9:3:3:1 ratio. This can be attributed to the fact that:
| 1. | The genes are located on the X and Y chromosomes. |
| 2. | Fruit fly has abnormal chromosomes. |
| 3. | The genes are located on the X chromosome. |
| 4. | The genes exhibit incomplete dominance. |
The number of alleles, the genotypic combinations, and phenotypes in the ABO system are respectively:
| 1. | 3, 6 and 4 | 2. | 3, 4 and 6 |
| 3. | 2, 3 and 4 | 4. | 2, 3, and 6 |
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