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. |
Pedigree analysis is used for genetic analysis in humans rather than conventional genetic methods because:
I: | Choice matings are not possible. |
II: | The number of progeny is limited. |
Of the two statements:
1. | Only I is correct | 2. | Only II is correct |
3. | Both I and II are correct | 4. | Both I and II are incorrect |
A plant with the genotype Tt should be called:
1. | Heterologous | 2. | Hemizygous |
3. | Heterozygous | 4. | Dihybrid |
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 number of autosomes in a human egg would be:
1. | 22 | 2. | 23 |
3. | 1 | 4. | 2 |
In cases of Phenylketonuria:
1. | The affected individual lacks an enzyme that converts the amino acid tyrosine into phenylalanine. |
2. | The affected individual makes an enzyme that converts the amino acid tyrosine into phenylalanine. |
3. | The affected individual makes an enzyme that converts the amino acid phenylalanine into tyrosine. |
4. | The affected individual lacks an enzyme that converts the amino acid phenylalanine into tyrosine. |
In sickle cell anaemia, the mutant haemoglobin molecule undergoes:
1. | Polymerisation under low oxygen tension causing changes in the shape of the RBC to a sickle-like structure |
2. | Depolymerisation under low oxygen tension causing that changes the shape of the RBC to a sickle-like structure |
3. | Denaturation under high oxygen tension causing changes in the shape of the RBC to a sickle-like structure |
4. | Denaturation |
T. H. Morgan worked on the fruit fly, Drosophila melanogaster. Which of the following is not an advantage of this fly?
1. | They could be grown on a simple synthetic medium in the laboratory. |
2. | They complete their life cycle in about two years, and a single mating could produce a large number of progeny flies. |
3. | There was a clear differentiation of the sexes – the male and female flies are easily distinguishable. |
4. | It has many types of hereditary variations that can be seen with low-power microscopes. |
In true breeding, the allelic pair of genes are:
1. | Homologous | 2. | Linked |
3. | Stable | 4. | Homozygous |
What proportion of progeny in F2 generation in a Mendel monohybrid cross resembled the parent [of P generation] that expressed the recessive trait?
1. | ¼ | 2. | ½ |
3. | ¾ | 4. | 2/3 |