Principles of Inheritance and Variation

If both parents are carriers for thalassemia, which is an autosomal recessive disorder, what are the chances of pregnancy resulting in an affected child ?

1. 100%
2. 25%
3. no chance
4. 50%

If two persons with 'AB' blood group marry and have sufficiently large number of children, these children could be classified as 'A' blood group : 'AB' blood group : 'B' blood group in 1 : 2 : 1 ratio. Modern technique of protein electrophoresis reveals presence of both 'A' and 'B' type proteins in 'AB' blood group individuals. This is an example of :

1. Codominance
2. Partial dominance
3. Incomplete dominance
4. Complete dominance

Which idea is depicted by a cross in which the F1 generation resembles both the parents?

1. law of dominance
2. co-dominance
3. incomplete dominance
4. inheritance of one gene

Which of the following statements is not true of two genes that show 50% recombination frequency ?

1. The genes are tightly linked
2. The genes show independent assortment
3. If the genes are present on the same chromosome, they undergo more than one crossovers in every meiosis.
4. The genes may be on different chromosomes

In our society women are blamed for producing female children. Choose the correct answer for the sex-determination in humans.

1. Due to some defect like aspermia in man
2. Due to the genetic make up of the particular sperm which fertilizes the egg
3. Due to the genetic make up of the egg
4. Due to some defect in the women

Which one is the incorrect statement with regards to the importance of pedigree analysis?

1. It confirms that DNA is the carrier of genetic information
2. It helps to trace the inheritance of a specific trait
3. It confirms that the trait is linked to one of the autosome
4. It helps to understand whether the trait in question is dominant or recessive

Down's syndrome in humans is due to :

1. Three 'X' chromosomes
2. Monosomy
3. Three copies of chromosome 21
4. Two 'Y' chromosomes

Represented below is the inheritance pattern of a certain type of traits in humans. Which one of the following conditions could be an example of this pattern ? [figure]

1. Haemophilia
2. Sickle cell anaemia
3. Thalassemia
4. Phenylketonuria

A test cross is carried out to :

1. Determine whether two species or varieties will breed successfully
2. Determine the genotype of a plant at F2
3. Predict whether two traits are linked
4. Assess the number of alleles of a gene

Which one of the following is a wrong statement regarding mutations ?

1. UV and gamma rays are mutagens
2. Deletion and insertion of base pairs cause frame-shift mutations
3. Cancer cells commonly show chromosomal aberrations
4. Change in a single base pair of DNA does not cause mutation