Question

chapter 10: dihybrid cross worksheet
date
in rabbits, gray hair is dominant to white hair. also in rabbits, black eyes are dominant to red eyes. these letters represent the genotypes of the rabbits:
gg = gray hair
gg = gray hair
gg = white hair
bb = black eyes
bb = black eyes
bb = red eyes

1. what are the phenotypes (descriptions) of rabbits that have the following genotypes?

ggbb
ggbb
ggbb

1. a male rabbit with the genotype ggbb is crossed with a female rabbit with the genotype ggbb the square is set up below. fill it out and determine the phenotypes and proportions in the offspring.

how many out of 16 have gray fur and black eyes? ______
how many out of 16 have gray fur and red eyes? ______
how many out of 16 have white fur and black eyes? ______
how many out of 16 have white fur and red eyes? ______

1. a male rabbit with the genotype ggbb is crossed with a female rabbit with the genotype ggbb the square is set up below. fill it out and determine the phenotypes and proportions of offspring

how many out of 16 have gray fur and black eyes? ______
how many out of 16 have gray fur and red eyes? ______
how many out of 16 have white fur and black eyes? ______
how many out of 16 have white fur and red eyes? ______

Explanation:

Step1: Solve Question 1 (Phenotypes)

Match genotypes to traits:

• $Ggbb$: Gray hair (G dominant), red eyes (bb recessive)
• $ggBb$: White hair (gg recessive), black eyes (B dominant)
• $ggbb$: White hair (gg recessive), red eyes (bb recessive)
• $GgBb$: Gray hair (G dominant), black eyes (B dominant)

Step2: Solve Question 2 (Punnett Square)

Step2a: Identify offspring genotypes

All top gametes: $Gb$; Left gametes: $gB, gB, gb, gb$
Offspring genotypes:

• 8 $GgBb$, 8 $Ggbb$

Step2b: Count phenotypes

• Gray fur + black eyes ($GgBb$): 8 out of 16
• Gray fur + red eyes ($Ggbb$): 8 out of 16
• White fur + black eyes: 0 out of 16
• White fur + red eyes: 0 out of 16

Step3: Solve Question 3 (Punnett Square)

Step3a: Classify offspring phenotypes

• Gray fur + black eyes (G_ B_): $GGBB, GGBb, GgBB, GgBb, GGBb, GgBb, GgBB, GgBb, GgBb$ → 9 out of 16
• Gray fur + red eyes (G_ bb): $GGbb, Ggbb, Ggbb$ → 3 out of 16
• White fur + black eyes (gg B_): $ggBB, ggBb, ggBb$ → 3 out of 16
• White fur + red eyes (gg bb): $ggbb$ → 1 out of 16

Answer:

1.

• $Ggbb$: Gray hair, red eyes
• $ggBb$: White hair, black eyes
• $ggbb$: White hair, red eyes
• $GgBb$: Gray hair, black eyes

2.

• Gray fur and black eyes: 8 out of 16
• Gray fur and red eyes: 8 out of 16
• White fur and black eyes: 0 out of 16
• White fur and red eyes: 0 out of 16

3.

• Gray fur and black eyes: 9 out of 16
• Gray fur and red eyes: 3 out of 16
• White fur and black eyes: 3 out of 16
• White fur and red eyes: 1 out of 16