The recessive genes located on X-chromosomes in humans are always:

1. Sub-lethal

2. Expressed in males

3. Expressed in females

4. Lethal

A male human is heterozygous for autosomal genes A and B and is also hemizygous for hemophilic gene h. What proportion of his sperm will be ABH?

A self-fertilizing trihybrid plant forms:

Lack of independent assortment of two genes A and B in the fruit fly Drosophila is due to:

1. Recombination

2. Linkage

3. Crossing over

4. Repulsion 

Life span of worker honey bee:
1.  30 days
2.  15 days
3.  90 days
4.  10 days

In a plant red fruit (R) is dominant over yellow fruit (r) and tallness (T) is dominant over shortness (t). If a plant with RRTt genotype is crossed with a plant that is rrtt:

1. 50% will be tall with red fruit

2. 75% will be tall with red fruit

3. All the offspring will be tall with red fruit

4. 25% will be tall with red fruit

One of the parents of a cross has a mutation in its mitochondria. In that cross, that parent is taken as a male. During the segregation of $F_2$ progenies that mutation is found in:

1. None of the progenies

2. All the progenies

3. 50% of the progenies

4. 1/3 of the progenies 

What change occurs by changing one base in DNA:
1.  Always a change of one amino acid in protein
2.  Change in complex sequence of amino acid
3.  Always a change in property of protein
4.  Does not necessarily change the phenotype

When a diploid female plant is crossed with a tetraploid male, the ploidy of endosperm cells in the resulting seed is:

1. Pentaploidy

2. Diploidy

3. Triploidy

4. Tetraploidy

The allele for tallness is dominant over that of dwarfness. This is called:
1.  Law of independent assortment
2.  Law of segregation
3.  Law of unit character
4.  Law of dominance