Two Factor Crosses I

Question 1

Two-factor crosses:

Answer 1

Two characters are controlled by 1 gene.
or
Two genes are controlled by 1 character.

Also called a Dihybrid cross.

Question 2

Coat color in cats:

Answer 2

There are 5 genes that affect different aspects of coat color.

Question 3

Why are 2-factor crosses used:

Answer 3

It is used in the selective breeding of domesticated animals or plants.

You can select for traits of multiple characters at the same time.

Question 4

5 Genes in cats:

Answer 4

Gene 1: Pigment production.
Gene 2: Pigment color.
Gene 3: Pigment quality.
Gene 4: Pigment distribution (even/uneven).
Gene 5: Pigment distribution in the coat.

Question 5

Example of a 2-factor cross:

Answer 5

Garden pea plant.

Question 6

Phenotypic ratio for F2 generation:

Answer 6

9:16- Both dominant phenotypes.
3:16- 1 dominant, 1 recessive.
3:16- 1 dominant, 1 recessive.
1:16- Both recessive.

Question 7

Seed color in garden peas:

Answer 7

Dominant allele: G (Yellow seed).
Recessive allele: g (Green seed).

Question 8

Seed shape in garden peas:

Answer 8

Dominant allele: R ( Round seed).
Recessive allele: r ( Wrinkled seed).

Question 9

Gene interaction:

Answer 9

One character is controlled by two genes.
Ex: Comb shape in chickens.

Question 10

Comb shape in chickens:
* This is an example of gene interaction.

Answer 10

Walnut.
Rose.
Pea.
Single.

Question 11

What two genes affect comb shape:

Answer 11

Pea gene.
Rose gene.
Both genes are on autosomes.

Question 12

Walnut genotype:

Answer 12

At least one dominant allele for both genes.

Question 13

Rose genotype:

Answer 13

At least one dominant allele for the rose gene and homozygous recessive for the pea gene.

Question 14

Pea gene:

Answer 14

At least one dominant allele for the pea gene, and homozygous recessive for the rose gene.

Question 15

Single:

Answer 15

Homozygous recessive for both genes.