Worksheet on genetic crosses involving two traits in rabbits, including Punnett squares and phenotype predictions.

Problem Analysis:

The task involves understanding genetic crosses in rabbits, focusing on two traits: hair color and eye color. The given information is:
- Hair color: Gray hair (G) is dominant over white hair (g).
- Eye color: Black eyes (B) are dominant over red eyes (b).

We need to solve the problems step by step using Mendelian genetics principles.

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

#### Genotypes:
- GgBb
- ggBb
- ggbb

#### Solution:
To determine the phenotype, we analyze each genotype based on the dominance relationships:
- Gray hair (G) is dominant over white hair (g).
- Black eyes (B) are dominant over red eyes (b).

##### (a) GgBb
- Hair color: Gg → Gray hair (dominant allele G is present).
- Eye color: Bb → Black eyes (dominant allele B is present).
- Phenotype: Gray fur and black eyes.

##### (b) ggBb
- Hair color: gg → White hair (no dominant G allele).
- Eye color: Bb → Black eyes (dominant allele B is present).
- Phenotype: White fur and black eyes.

##### (c) ggbb
- Hair color: gg → White hair (no dominant G allele).
- Eye color: bb → Red eyes (no dominant B allele).
- Phenotype: White fur and red eyes.

#### Final Answer for Question 1:
$$
\boxed{\text{GgBb: Gray fur and black eyes; ggBb: White fur and black eyes; ggbb: White fur and red eyes}}
$$

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2. A male rabbit with the genotype GgBb is crossed with a female rabbit with the genotype ggbb. Determine the phenotypes and proportions in the offspring.

#### Step 1: Identify the gametes produced by each parent.
- Male (GgBb):
- Possible gametes: GB, Gb, gB, gb (each with equal probability of 25%).
- Female (ggbb):
- Possible gametes: gb (only one type, as both alleles are recessive).

#### Step 2: Create a Punnett square.
We will cross the male's gametes (GB, Gb, gB, gb) with the female's gamete (gb).

| | gb |
|-----|----|
| GB | GgBb |
| Gb | Ggbb |
| gB | ggBb |
| gb | ggbb |

#### Step 3: Determine the phenotypes of the offspring.
- GgBb: Gray fur and black eyes.
- Ggbb: Gray fur and red eyes.
- ggBb: White fur and black eyes.
- ggbb: White fur and red eyes.

#### Step 4: Calculate the proportions.
Each combination (GgBb, Ggbb, ggBb, ggbb) appears once in the Punnett square, so each phenotype occurs with a probability of 25%.

#### Final Answer for Question 2:
$$
\boxed{\text{Gray fur and black eyes (25%), Gray fur and red eyes (25%), White fur and black eyes (25%), White fur and red eyes (25%) }}
$$

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3. A male rabbit with the genotype GgBb. Determine the gametes produced by this rabbit (the sperm). How many combinations are there?

#### Solution:
The male rabbit has the genotype GgBb. To determine the gametes, we use the principle of independent assortment:
- The alleles for hair color (G, g) assort independently of the alleles for eye color (B, b).

Possible gametes are:
1. GB
2. Gb
3. gB
4. gb

There are 4 possible combinations.

#### Final Answer for Question 3:
$$
\boxed{\text{GB, Gb, gB, gb; 4 combinations}}
$$

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4. A female rabbit has the genotype ggBb. Determine the gamets (eggs) produced by this rabbit.

#### Solution:
The female rabbit has the genotype ggBb. To determine the gametes, we consider the alleles for each trait:
- For hair color: gg → only g can be passed on.
- For eye color: Bb → B or b can be passed on.

Possible gametes are:
1. gB
2. gb

#### Final Answer for Question 4:
$$
\boxed{\text{gB, gb}}
$$

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Final Summary of Answers:

1. $$ \boxed{\text{GgBb: Gray fur and black eyes; ggBb: White fur and black eyes; ggbb: White fur and red eyes}} $$
2. $$ \boxed{\text{Gray fur and black eyes (25%), Gray fur and red eyes (25%), White fur and black eyes (25%), White fur and red eyes (25%) }} $$
3. $$ \boxed{\text{GB, Gb, gB, gb; 4 combinations}} $$
4. $$ \boxed{\text{gB, gb}} $$