Heterozygotes for cystic fibrosis had a survival advantage during plague epidemics. This can be explained by
1. Multiple alleles
2. Overdominance
3. Environmental influence
4. Epistasis

Resistance to sudden death is a dominant trait in soybeans. Two parent plants that are resistant to sudden death produce a progeny that is not resistant, but this progeny can pass the trait to its progeny in the next generation. This unusual pattern can be explained by?
1. Overdominance
2. Incomplete penetrance
3. Incomplete dominance
4. Variable expressivity

Multiple alleles are present:

1. on different chromosomes
2. at different loci on the same chromosome
3. at the same locus of the chromosome
4. on non-sister chromatids

Mother and father of a person with ‘O’ blood group have ‘A’ and ‘B’ blood group, respectively. What would be the genotype of both mother and father?

1. Mother is homozygous for ‘A’ blood group and father is heterozygous for ‘B’

2. Mother is heterozygous for ‘A’ blood group and father is homozygous for ‘B’

3. Both mother and father are heterozygous for ‘A’ and ‘B’ blood group, respectively

4. Both mother and father are homozygous for ‘A’ and ‘B’ blood group, respectively