The ultimate source of allelic variation is:

(1) Recombination

(2) Natural selection

(3) Mutation

(4) Drift

In the case of co-dominance, the F₁ generation resembles:

(1) Dominant parent

(2) Recessive parent

(3) Both the parents

(4) None of the parents

What can be the possible blood groups of progeny whose father and mother are of A and B group respectively?

(1) A and B only

(2) AB only

(3) All except O

(4) A, B, AB and O

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 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

What is incorrect for Hemophilia?

1. In this disease, a single protein that is a part of the cascade of proteins involved in the clotting of blood is affected.

2. In an affected indlvidual a simple cut will result in non-stop bleeding.

3. The heterozygous female (carrier) for haemophilia may transmit the disease to sons.

4. The possibility of a female becoming a haemophilic is extremely rare because mother of such a female has to be hemophilic and the father should be a carrier.

Sickle cell anaemia results from.

1. A chromosomal aberration

2. Non disjunction of autosome

3. A point mutation

4. Blood transfusion reaction

What is the mode of inheritance of phenylketonuria?

1. Autosomal recessive

2. Autosomal dominant

3. Sex linked recessive

4. Sex linked dominant

Failure of cytokinesis after telophase stage of cell divislon results in an increase in a whole set of chromosomes in an organism and, this phenomenon is known as:

1. Aneuploidy

2. Translocation

3. Polyploidy.

4. Inversion

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 trisomy of chromosome 21

3. The aflected individual has a characteristic simian palmar crease

4. The mental development of affected individual is normal

Identify the incorrect statement:

(1) In addition to recombination, mutation is another phenomeonon that leads to variation in DNA.

(2) Chromosomal aberrations are commonly observed in cancer cells.

(3) A classical example of a point mutation is sickle cell anaemia.

(4) Non ionising radiations cannot be mutations.