Which one of the following conditions correctly describes the manner of determining the sex in the given example?
 

1.	XO type of sex chromosomes determines male sex in grasshopper
2.	XO condition in humans as found in Turner syndrome, determines female sex
3.	Homozygous sex chromosomes (XX) produce males in Drosophila
4.	Homozygous sex chromosomes (ZZ) determine the female sex in birds.

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

Two genes R and Y are located very close on the chromosomal linkage map of the maize plant. When RRYY and rryy genotypes are hybridized, then F₂ segregation will show:

1. higher number of the recombinant types

2. segregation in the expected 9:3:3:1 ratio

3. segregation in a 3:1 ratio

4. higher number of the parental types