Which one of the following cannot be explained on the basis of Mendel's Law of Dominance?

1.	The discrete unit controlling a particular character is called a factor.
2.	Out of one pair of factors, one is dominant, and the other recessive.
3.	Alleles do not show any blending and both the characters recover as such in the F2 generation.
4.	Factors occur in pairs.

The genotype of a plant showing the dominant phenotype can be determined by:

1. test cross

2. dihybrid cross

3. pedigree analysis

4. back cross

ABO blood groups in humans are controlled by the gene I. It has three alleles – I^A I^B and i. Since there are three different alleles, six different genotypes are possible. How many phenotypes can occur?

1. Three

2. One

3. Four

4. Two

Select the correct statement from the ones given below with respect to dihybrid cross:

Sickle cell anaemia is:

Point mutation involves:

1. insertion

2. change in single base pair

3. duplication 

4. deletion

Study the pedigree chart given below:

What does it show?

Inheritance of skin colour in humans is an example of:

1. chromosomal aberration

2. point mutation

3. polygenic inheritance

4. codominance