AM - Transmission Genetics 2

Question 1

What is incomplete dominance?

Answer 1

Red flowered RR crossed with rr (white) gives Rr (pink)
-Intermediate phenotype shown

• F1 generation shows a 4:0:0 phenotypic ratio
• F2 generation shows a 1:2:1 phenotypic ratio

Question 2

What is co-dominance?

Answer 2

Phentoypes of both dominant alleles are present
* Blood groups show codominance

Question 3

What are lethal alleles?

Answer 3

The combination of specific alleles lead to death of the organism
* Ratio of 1:2:1 changed to 2:1 due to homozygous lethal

Question 4

What is the phenotypic ratio for a regular dyhibrid cross?

Answer 4

9:3:3:1

Question 5

What is recessive epistasis and what is its phenotypic ratio?

Answer 5

When the recessive allele of one gene hides the expression of all alleles of another gene
* 9:3:4

Question 6

What is dominant epistasis and what is its phenotypic ratio?

Answer 6

When the dominant allele of one gene hides the expression of all alleles of another gene
* 12:3:1

Question 7

What is recipricol recessive epistasis and what is its phenotypic ratio?

Answer 7

The pigment is hidden if homozygous recessive pairs are present
* 9:7

Question 8

What is duplicate genes with the cumulative effect and what is its phenotypic ratio?

Answer 8

Presence of at least one dominant allele from each gene pair results in individual colour
* 9:6:1

Question 9

What is duplicate dominant genes and what is its phenotypic ratio?

Answer 9

Both dominant alleles have an identical effect
* 15:1

Question 10

What is dominant and recessive interaction and what is its phenotypic ratio?

Answer 10

Colour production is controlled by the dominant B allele unless the pathway is blocked by the dominant A allele
* 13:3