Epistasis

Question 1

(12: 3 : 1)

Answer 1

Dominant Epistasis

Question 2

(9 : 3 : 4)

Answer 2

Recessive Epistasis

Question 3

(9: 6: 1)

Answer 3

Duplicate Genes with Cumulative Effect

Question 4

(9: 7)

Answer 4

Duplicate Recessive Genes (or Complimentary genes)

Question 5

(15: 1)

Answer 5

Duplicate Dominant Genes

Question 6

(13: 3)

Answer 6

Dominant and Recessive Interactions

Question 7

When out of two genes, the dominant allele (e.g., A) of one gene masked the activity of alleles of another gene (e.g., B) and expressed itself phenotypically, then A gene locus is said to be epistatic to the B gene locus

Answer 7

Dominant Epistasis (12: 3 : 1)

Question 8

Because, the dominant allele A can express itself only in the presence of either B or b allele, therefore, such type of epistasis is termed as

Answer 8

dominant epistasis

Question 9

Sometimes the recessive alleles of one gene locus (aa) mask the action (phenotypic expression) of alleles of another gene locus (BB, Bb or bb alleles). This type of epistasis is called m

Answer 9

Recessive Epistasis (9 : 3 : 4)

Question 10

Certain phenotypic traits (e.g., coat colouration) depend on the dominant alleles of two gene loci.

When the dominant condition (homozygous or heterozygous) at either locus (but not both) produces the same phenotype, the F2 ratio becomes 9: 6: 1.

Answer 10

Duplicate Genes with Cumulative Effect (9: 6: 1)

Question 11

If both gene loci have homozygous recessive alleles and both of them produce identical phenotypes, the F2 ratio 9: 3: 3: 1 would become 9: 7.

In such case, the genotypes aa BB, aa Bb, AA bb, Aa bb, and aa bb produce one phenotype (Table 47).

Answer 11

Duplicate Recessive Genes (or Complimentary genes)

(9: 7)

Question 12

genotypes aa BB, aa Bb, AA bb, Aa bb, and aa bb produce one phenotype (Table 47). Both dominant alleles when present together, complement each other and are called complementary genes and produce a different phenotype

Answer 12

Duplicate Recessive Genes (or Complimentary genes)

(9: 7)

Question 13

If the dominant alleles of both gene loci produce the same phenotype without cumulative effect, the 9: 3 : 3 : 1 ratio is modified into a 15 : 1 ratio .

Answer 13

Duplicate Dominant Genes (15: 1)

Question 14

Sometimes, the dominant alleles of one gene locus (A) in homozygous (AA) and heterozygous (Aa) condition and the homozygous recessive alleles (bb) of another gene locus (B) produce the same phenotype, the F2 phenotypic ratio becomes 13: 3 instead of 9: 3 : 3 : 1. In such case, the genotype AA BB, AABb, Aa BB, Aa Bb, AA bb and Aa bb produce same phenotype and the genotype aa BB, aa Bb and aa bb produce another but same phenotype.

Answer 14

Dominant and Recessive Interactions (13: 3)