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Let's solve this Dihybrid Cross Worksheet step by step.

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Key Information:

- Hair color:
- G = gray hair (dominant)
- g = white hair (recessive)
- Eye color:
- B = black eyes (dominant)
- b = red eyes (recessive)

So:
- GG, Gg → gray hair
- gg → white hair
- BB, Bb → black eyes
- bb → red eyes

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## Question 1: Phenotypes of given genotypes

We are asked to determine the phenotype (observable traits) for each genotype.

1. Ggbb
- Hair: Gg → gray hair (since G is dominant)
- Eyes: bb → red eyes (since b is recessive and homozygous)
- ✔ Gray hair, red eyes

2. ggBB
- Hair: gg → white hair
- Eyes: BB → black eyes
- ✔ White hair, black eyes

3. ggb
- Hair: gg → white hair
- Eyes: bb → red eyes
- ✔ White hair, red eyes

4. GgBb
- Hair: Gg → gray hair
- Eyes: Bb → black eyes
- ✔ Gray hair, black eyes

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✔ Answers for Question 1:

- Ggbb: Gray hair, red eyes
- ggBB: White hair, black eyes
- ggb: White hair, red eyes
- GgBb: Gray hair, black eyes

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## Question 2: Cross between male GGbb × female ggBb

Step 1: Determine gametes

- Male: GGbb
- Gametes: Since both genes are homozygous, only one type: Gb
- G from hair gene, b from eye gene
- So all sperm: Gb

- Female: ggBb
- Hair: gg → only g
- Eyes: Bb → can be B or b
- So gametes: gB and gb (each with 50% chance)

But since we're doing a Punnett square with 4 boxes, we need to write all possible combinations:

Actually, the male produces only one type of gamete: Gb
The female produces two types: gB and gb, but we must use four boxes as shown in the grid.

Wait — the square has 4 columns labeled Gb, Gb, Gb, Gb → that means the male contributes Gb in all cases.

And rows: gB, gB, gb, gb → so female contributes gB twice and gb twice (to make 4 total).

So we fill the 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 let’s count:

- GgBb: appears 8 times → gray fur, black eyes
- Ggbb: appears 8 times → gray fur, red eyes

Wait! But the question asks "How many out of 16" — so we have 16 boxes.

Let’s count:

- GgBb: 8 boxes → gray fur, black eyes
- Ggbb: 8 boxes → gray fur, red eyes

No white fur (because all offspring have G from father, so Gg → gray)

So:

- Gray fur & black eyes: 8/16
- Gray fur & red eyes: 8/16
- White fur & black eyes: 0/16
- White fur & red eyes: 0/16

✔ Answer for Question 2:

- How many out of 16 have gray fur and black eyes? → 8
- How many out of 16 have gray fur and red eyes? → 8
- How many out of 16 have white fur and black eyes? → 0
- How many out of 16 have white fur and red eyes? → 0

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## Question 3: Cross between GgBb × GgBb

This is a classic dihybrid cross.

Step 1: Gametes

Each parent: GgBb

Gametes: All combinations of alleles:

- GB, Gb, gB, gb — each with equal probability (25%)

So we set up a 4×4 Punnett square.

Columns: GB, Gb, gB, gb (from male)
Rows: GB, Gb, gB, gb (from female)

Let’s fill it in:

| | 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 let’s analyze phenotypes.

We’ll count how many of each phenotype appear.

Step 2: Determine phenotypes

We go through each box:

1. GGBB → gray, black → ✔
2. GGBb → gray, black → ✔
3. GgBB → gray, black → ✔
4. GgBb → gray, black → ✔
5. GGBb → gray, black → ✔
6. GGbb → gray, red → ✘
7. GgBb → gray, black → ✔
8. Ggbb → gray, red → ✘
9. GgBB → gray, black → ✔
10. GgBb → gray, black → ✔
11. ggBB → white, black → ⚫
12. ggBb → white, black → ⚫
13. GgBb → gray, black → ✔
14. Ggbb → gray, red → ✘
15. ggBb → white, black → ⚫
16. ggbb → white, red → 🔴

Now count:

Count each phenotype:

#### Gray fur & black eyes:
- Must have G_ (GG or Gg) and B_ (BB or Bb)
- From above:
- GGBB (1)
- GGBb (2)
- GgBB (2)
- GgBb (4)
- Total: 1 + 2 + 2 + 4 = 9

Wait, let's list them:

- Row 1: GGBB, GGBb, GgBB, GgBb → 4
- Row 2: GGBb, GGbb, GgBb, Ggbb → GGBb and GgBb → 2 more
- Row 3: GgBB, GgBb, ggBB, ggBb → GgBB, GgBb → 2 more
- Row 4: GgBb, Ggbb, ggBb, ggbb → GgBb → 1 more

Total: 4 + 2 + 2 + 1 = 9

✔ Gray fur & black eyes: 9

#### Gray fur & red eyes:
- G_ and bb
- Must be: GGbb or Ggbb
- From square:
- GGbb: appears once (row 2, col 2)
- Ggbb: appears in (row 2, col 4), (row 4, col 2), (row 4, col 4)? Wait:

Check:

- Row 2, col 2: GGbb → yes
- Row 2, col 4: Ggbb → yes
- Row 4, col 2: Ggbb → yes
- Row 4, col 4: ggbb → no (white)
- Also row 3, col 4: ggBb → no
- Row 4, col 1: GgBb → no

So: GGbb → 1
Ggbb → 2 (positions: (2,4) and (4,2))

Wait — actually:

- (2,2): GGbb
- (2,4): Ggbb
- (4,2): Ggbb
- (4,4): ggbb → not gray

So total: 3

But wait — let’s check again:

From the table:

- (2,2): GGbb → gray, red → ✔
- (2,4): Ggbb → gray, red → ✔
- (4,2): Ggbb → gray, red → ✔
- Any others?

(1,4): GgBb → black eyes → no
(3,4): ggBb → white → no
(4,4): ggbb → white → no

So only 3?

Wait — standard dihybrid ratio is 9:3:3:1

So should be:

- 9: gray-black
- 3: gray-red
- 3: white-black
- 1: white-red

So we should have 3 gray-red.

Yes — we have:

- GGbb → 1
- Ggbb → 2 (from two positions)

Total: 3 → ✔

#### White fur & black eyes:
- gg and B_
- ggBB or ggBb

From table:

- (3,3): ggBB → white, black → ✔
- (3,4): ggBb → white, black → ✔
- (4,3): ggBb → white, black → ✔
- (4,4): ggbb → white, red → no

So: (3,3), (3,4), (4,3) → 3

✔ 3

#### White fur & red eyes:
- gg and bb → ggbb
- Only one: (4,4)

✔ 1

Final counts:

- Gray fur & black eyes: 9
- Gray fur & red eyes: 3
- White fur & black eyes: 3
- White fur & red eyes: 1

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✔ Answers for Question 3:

- How many out of 16 have gray fur and black eyes? → 9
- How many out of 16 have gray fur and red eyes? → 3
- How many out of 16 have white fur and black eyes? → 3
- How many out of 16 have white fur and red eyes? → 1

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## ✔ Final Answers Summary

Question 1:

- Ggbb: Gray hair, red eyes
- ggBB: White hair, black eyes
- ggb: White hair, red eyes
- GgBb: Gray hair, black eyes

Question 2:

- Gray fur & black eyes: 8
- Gray fur & red eyes: 8
- White fur & black eyes: 0
- White fur & red eyes: 0

Question 3:

- Gray fur & black eyes: 9
- Gray fur & red eyes: 3
- White fur & black eyes: 3
- White fur & red eyes: 1

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Let me know if you'd like the Punnett squares filled in visually or explained further!