Dihybrid Punnett Square Practice worksheet for learning genetics, featuring problems on rabbit traits including gray vs. white hair and black vs. red eyes, with a Punnett square grid to determine offspring phenotypes and proportions.

Let's solve each part of this Dihybrid Punnett Square Practice step by step, with clear explanations.

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Given Information:

- Gray hair (G) is dominant to white hair (g)
- Black eyes (B) are dominant to red eyes (b)
- Traits are independent (Mendel’s Law of Independent Assortment)

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## 1. Phenotypes for given genotypes

We determine the phenotype based on dominance:

| Genotype | Hair Color | Eye Color | Phenotype |
|---------|------------|-----------|----------|
| Ggbb | G = gray (dominant), g = white → gray | bb = recessive → red eyes | Gray, red-eyed |
| ggBB | gg = recessive → white hair | BB = dominant → black eyes | White, black-eyed |
| ggbb | gg = white | bb = red eyes | White, red-eyed |
| GgBb | Gg = gray | Bb = black eyes | Gray, black-eyed |

✔ Answers:
- Ggbb: Gray, red-eyed
- ggBB: White, black-eyed
- ggbb: White, red-eyed
- GgBb: Gray, black-eyed

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## 2. Cross: Male GGbb × Female ggBb

Step 1: Determine gametes

- Male: GGbb → Gametes: All combinations of G and b → Only Gb
- Female: ggBb → Gametes: gB or gb → So: gB, gb

So the male produces only Gb gametes. The female produces gB and gb in equal amounts.

But since the Punnett square has 4 columns for Gb, we assume all four are Gb (since male is homozygous).

Fill in the Punnett Square:

| | Gb | Gb | Gb | Gb |
|-------|--------|--------|--------|--------|
| gB | GgBb | GgBb | GgBb | GgBb |
| gB | GgBb | GgBb | GgBb | GgBb |
| gb | Ggbb | Ggbb | Ggbb | Ggbb |
| gb | Ggbb | Ggbb | Ggbb | Ggbb |

Now count the phenotypes:

- GgBb: Gray hair (G), black eyes (B) → Gray, black-eyed
- Ggbb: Gray hair (G), red eyes (bb) → Gray, red-eyed

So:
- Gray, black-eyed: 8 out of 16
- Gray, red-eyed: 8 out of 16
- White, black-eyed: 0
- White, red-eyed: 0

✔ Answers:
- Grey, red-eyed: 8
- Grey, black-eyed: 8
- White, red-eyed: 0
- White, black-eyed: 0

> Note: This is a test cross for eye color, but hair color is fixed as gray due to male being GG.

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## 3. Gametes from male rabbit: GgBb

Since alleles assort independently, possible gametes are all combinations of one allele from each gene:

- G and B → GB
- G and b → Gb
- g and B → gB
- g and b → gb

✔ Gametes: GB, Gb, gB, gb

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## 4. Gametes from female rabbit: ggBb

She is homozygous for white hair (gg), so only g for hair.

For eyes: Bb → B or b

So gametes:
- gB
- gb

✔ Gametes: gB, gb

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## 5. Punnett Square: Male GgBb × Female ggBb

Male gametes (top): GB, Gb, gB, gb
Female gametes (side): gB, gb

Set up 4×2 Punnett square:

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

Now interpret each genotype:

| Genotype | Hair | Eyes | Phenotype |
|---------|------|------|-------------------|
| GgBB | Gray | Black | Gray, black-eyed |
| GgBb | Gray | Black | Gray, black-eyed |
| ggBB | White| Black | White, black-eyed |
| ggBb | White| Black | White, black-eyed |
| Ggbb | Gray | Red | Gray, red-eyed |
| ggbb | White| Red | White, red-eyed |

Now count:

- Gray, black-eyed: GgBB, GgBb →
- GgBB: 1
- GgBb: 2 (one from GB+gb, one from Gb+gB)
→ Total: 3
- Gray, red-eyed: Ggbb → 1
- White, black-eyed: ggBB, ggBb → 1 + 1 = 2
- White, red-eyed: ggbb → 1

Wait! Let's count carefully:

From the square:

1. gB × GB → GgBB → Gray, black-eyed ✔
2. gB × Gb → GgBb → Gray, black-eyed ✔
3. gB × gB → ggBB → White, black-eyed ✔
4. gB × gb → ggBb → White, black-eyed ✔
5. gb × GB → GgBb → Gray, black-eyed ✔
6. gb × Gb → Ggbb → Gray, red-eyed ✔
7. gb × gB → ggBb → White, black-eyed ✔
8. gb × gb → ggbb → White, red-eyed ✔

So total:

- Gray, black-eyed: GgBB (1), GgBb (2) → 3
- Gray, red-eyed: Ggbb → 1
- White, black-eyed: ggBB (1), ggBb (2) → 3
- White, red-eyed: ggbb → 1

Wait — that’s only 8 offspring? But it should be 8 boxes.

Yes, 4 male gametes × 2 female gametes = 8 offspring.

So:

| Phenotype | Count |
|-----------------------|-------|
| Gray, black-eyed | 3 |
| Gray, red-eyed | 1 |
| White, black-eyed | 3 |
| White, red-eyed | 1 |

✔ Final Answer:

- Gray, red-eyed: 1
- Gray, black-eyed: 3
- White, red-eyed: 1
- White, black-eyed: 3

(Proportions: 3:1:3:1)

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## 6. Cyclops: Antennae and Pesticide Resistance

Traits:

- Antennae: Barbed (dominant) vs. Smooth (recessive)
- Pesticide resistance: Recessive trait

Let’s assign alleles:

- Antennae:
- Barbed: B (dominant)
- Smooth: b (recessive)
- Pesticide resistance:
- Resistant: r (recessive)
- Not resistant: R (dominant)

Note: Resistance is recessive → must be rr to be resistant.

Possible Genotypes & Phenotypes:

| Genotype | Antennae | Pesticide Resistance | Phenotype |
|---------|----------|-----------------------|-----------|
| BBRR | Barbed | Not resistant | Barbed, not resistant |
| BBRr | Barbed | Not resistant | Barbed, not resistant |
| BBrr | Barbed | Resistant | Barbed, resistant |
| BbRR | Barbed | Not resistant | Barbed, not resistant |
| BbRr | Barbed | Not resistant | Barbed, not resistant |
| Bbrr | Barbed | Resistant | Barbed, resistant |
| bbRR | Smooth | Not resistant | Smooth, not resistant |
| bbRr | Smooth | Not resistant | Smooth, not resistant |
| bbrr | Smooth | Resistant | Smooth, resistant |

Key (Summary):

| Genotype | Phenotype |
|---------|----------------------------------|
| BBRR, BBRr, BbRR, BbRr | Barbed antennae, not resistant |
| BBrr, Bbrr | Barbed antennae, resistant |
| bbRR, bbRr | Smooth antennae, not resistant |
| bbrr | Smooth antennae, resistant |

✔ Key:
- Barbed, not resistant: BBRR, BBRr, BbRR, BbRr
- Barbed, resistant: BBrr, Bbrr
- Smooth, not resistant: bbRR, bbRr
- Smooth, resistant: bbrr

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✔ Final Answers Summary:

#### 1. Phenotypes:
- Ggbb → Gray, red-eyed
- ggBB → White, black-eyed
- ggbb → White, red-eyed
- GgBb → Gray, black-eyed

#### 2. Punnett Square (GGbb × ggBb):
- Grey, red-eyed: 8
- Grey, black-eyed: 8
- White, red-eyed: 0
- White, black-eyed: 0

#### 3. Gametes from GgBb male:
GB, Gb, gB, gb

#### 4. Gametes from ggBb female:
gB, gb

#### 5. Offspring from GgBb × ggBb:
- Gray, red-eyed: 1
- Gray, black-eyed: 3
- White, red-eyed: 1
- White, black-eyed: 3

#### 6. Cyclops Key:
- Barbed, not resistant: BBRR, BBRr, BbRR, BbRr
- Barbed, resistant: BBrr, Bbrr
- Smooth, not resistant: bbRR, bbRr
- Smooth, resistant: bbrr

Let me know if you'd like a visual version of any Punnett squares!