Punnett Squares Practice: Fill in the missing genes or genotypes in the Punnett squares for genetic inheritance exercises.

Let's solve each Punnett square step by step. The goal is to fill in the missing genotypes (gene combinations) for the offspring based on the parental alleles provided.

We'll go through each square one at a time, using standard Mendelian genetics rules:
- Each parent contributes one allele per gene.
- The dominant allele (uppercase) is listed first if present.
- We combine the alleles from the row and column to get the genotype of the offspring.

---

1. Square 1: B B × B b

```
B B
B BB BB
b Bb Bb
```
✔ All filled.

---

2. Square 2: B B × B B

```
B B
B BB BB
B BB BB
```
✔ All BB.

---

3. Square 3: b b × B b

```
b b
B Bb Bb
b bb bb
```
✔ Filled.

---

4. Square 4: B B × B b

```
B B
B BB BB
b Bb Bb
```
✔ Same as #1.

---

5. Square 5: B B × b b

```
B B
b Bb Bb
b Bb Bb
```
✔ All Bb.

---

6. Square 6: b b × b b

```
b b
b bb bb
b bb bb
```
✔ All bb.

---

7. Square 7: E e × E e

```
E e
E EE Ee
e Ee ee
```
✔ Filled.

---

8. Square 8: A a × A ?

Given: One child is Ae → but that’s not possible unless there's a typo.

Wait — the top row is A a
Left column is A and Ae? That can't be right.

Actually, look again:

The left side has:
- First row: A
- Second row: Ae

That’s not a valid gamete. Gametes are single alleles.

Ah! There must be a typo or mislabeling.

But wait — perhaps "Ae" is meant to be a, since the bottom row says "Ae", which is confusing.

Wait — actually, this might be a typo.

Looking closely:
- Top row: A a
- Left column: A and Ae?

That doesn’t make sense. A gamete can't be "Ae".

But below it says "Ae" — likely meant to be a.

So probably:
Parent 1: A a
Parent 2: A a

Then:

```
A a
A AA Aa
a Aa aa
```

But the problem says one offspring is "Ae" — which is invalid.

Wait — maybe the "Ae" is a mistake. Let's recheck.

Actually, the left side has:
- First: A
- Second: Ae

This is impossible. So likely a typo.

But in the box, the second row says Ae, which may be intended to mean a.

Alternatively, perhaps "Ae" is meant to be a, and the label is wrong.

But looking at the structure: It's a 2x2 grid.

Top: A a
Left: A and Ae → no.

Wait — perhaps it's A and a, and "Ae" is a typo.

But then why does it say "Ae"?

Another idea: Maybe it's A and a, and the bottom-left cell is Aa, but written as Ae? No.

Wait — let's assume it's a typo and the left column should be:

- A
- a

And the top is A a

Then:

```
A a
A AA Aa
a Aa aa
```

But the problem says one offspring is Ae — which is inconsistent.

Alternatively, maybe the letter is E, not A?

No — the letters are consistent.

Wait — perhaps the "Ae" is meant to be "a", and the "e" is a typo.

Yes — likely a typo. Probably meant to be:

Left side: A and a
Top: A and a

Then:

```
A a
A AA Aa
a Aa aa
```

So we’ll assume that.

✔ Final answer: AA, Aa, Aa, aa

---

9. Square 9: D d × d d

```
D d
d Dd dd
d Dd dd
```
✔ Filled.

---

10. Square 10: H H × H h

Wait — top: H H
Left: H and h

So:

```
H H
H HH HH
h Hh Hh
```
✔ Done.

---

11. Square 11: B ? × B b

Right side: B and b
Left side: B and b
One offspring is Bb

So the top row must be B and ?

But we have:
- Top: B and ?
- Left: B and b

One child is Bb → could come from B (top) + b (left), or b (top) + B (left)

But we know one offspring is Bb, and the other is Bb (already filled)

Wait — the square is:

```
B ?
B B? B?
b Bb Bb
```

Wait — no, the square is:

Top: B and ?
Left: B and b

And one cell is Bb → that’s the bottom-left: B (from left) + ? (from top)

But bottom-left is Bb, so B (from left) + ? = Bb → so ? = b

So top right is b

So top row: B and b

Now fill:

```
B b
B BB Bb
b Bb bb
```

But wait — the left side is B and b, top is B and b → yes.

But the square shows:

- Bottom-left: Bb → correct
- Bottom-right: Bb → but that would be b + b = bb → contradiction

Wait — the square is:

```
B ?
B ? ?
b Bb Bb
```

So bottom-left: b (left) + B (top) = Bb → OK
Bottom-right: b (left) + ? (top) = Bb → so ? = B

So top right is B

Then top: B and B
Left: B and b

So:

```
B B
B BB BB
b Bb Bb
```

But then bottom-right is Bb → b + B = Bb → OK

So the missing top right is B

So final:

```
B B
B BB BB
b Bb Bb
```

✔ Done.

---

12. Square 12: ? B × b Bb

Top: ? and B
Left: b and b
One offspring is Bb

So bottom-left: b (left) + ? (top) = Bb → so ? = B

So top left is B

Then top: B and B
Left: b and b

So:

```
B B
b Bb Bb
b Bb Bb
```

All Bb.

✔ Done.

---

13. Square 13: ? B × b Bb

Top: ? and B
Left: ? and b
One offspring is Bb

We see:
- Bottom-left: b (left) + ? (top) = Bb → so ? = B → top left is B
- Then top: B and B
- Left: ? and b

Now bottom-left: b + B = Bb → OK
But bottom-right: b + B = Bb → already given

Now top-left: ? + B = ?

We don’t know left-top yet.

But bottom-left is b + B = Bb → so left side must be b and something

Wait — the left side has two entries: first row is ?, second is b

We know bottom-left is b (left) + B (top) = Bb → OK

Now top-left: ? (left) + B (top) = ?

We don’t know what that is.

But we know one child is Bb, and the other in the bottom row is Bb.

But we need to find the missing alleles.

Wait — the square is:

```
? B
? ? ?
b Bb Bb
```

From bottom-left: b + ? = Bb → so ? = B → top left is B

So top: B and B

Now left side: ? and b

Now top-left: ? + B = ?

But we don’t know left-top.

But bottom-left is b + B = Bb → OK

Now bottom-right: b + B = Bb → OK

Now top-left: ? + B = ?

But we need to determine the left-top.

But no info yet.

But we know the offspring in top-left and top-right.

But nothing given.

Wait — maybe the left side is B and b

Because if left-top is B, then:

```
B B
B BB BB
b Bb Bb
```

Which matches.

So left side: B and b
Top: B and B

So:

```
B B
B BB BB
b Bb Bb
```

But the square shows only one known: bottom-left is Bb, bottom-right is Bb

So we can deduce:

- Left side: B and b
- Top: B and B

So missing:

- Top-left: B and B → BB
- Top-right: B and B → BB

So fill:

```
B B
B BB BB
b Bb Bb
```

✔ Done.

---

14. Square 14: R Rr × ? ?

Top: R and Rr → no, top is R and Rr? That can't be.

Wait — top: R and Rr → invalid.

Wait — the square is:

Top: R and Rr
Left: ? and ?

But Rr is a genotype, not an allele.

Wait — no — the top row is R and Rr — that’s not possible.

Wait — no — it's labeled:

Top: R and Rr
But Rr is two alleles — so likely a typo.

Wait — actually, the top row is R and Rr — but that's not how Punnett squares work.

Wait — looking again:

The square is:

```
R Rr
R ? ?
? ? rr
```

This is invalid.

Wait — perhaps the top is R and r
Left is R and r

But one offspring is rr

So:

```
R r
R RR Rr
r Rr rr
```

But the top row is labeled R and Rr — probably a typo.

Likely meant to be R and r

And left side: R and r

Then:

```
R r
R RR Rr
r Rr rr
```

But the square shows:

- Bottom-right: rr → OK
- Top-left: ? → RR
- Top-right: ? → Rr
- Bottom-left: ? → Rr

So fill accordingly.

But the labels are messy.

But given that one offspring is rr, and parents must be Rr × Rr

So top: R and r
Left: R and r

Then:

```
R r
R RR Rr
r Rr rr
```

✔ Done.

---

15. Square 15: ? ? × b Bb

Top: ? and ?
Left: ? and b
One offspring is Bb

But also: bottom-left is Bb

So b (left) + ? (top) = Bb → so ? = B

So top left is B

Now top: B and ?

Now bottom-left: b + B = Bb → OK

Now bottom-right: b + ? = ?

But we don’t know.

Also, left side: ? and b

Now top-left: ? + B = ?

But we need more.

Wait — the square is:

```
? ?
? ? ?
b Bb ?
```

But we know bottom-left is Bb → so b (left) + ? (top) = Bb → so top left is B

So top: B and ?

Now left side: ? and b

Now bottom-right: b + ? = ?

But we don’t know.

But also, top-left: ? (left) + B (top) = ?

But we don’t know.

But we know one offspring is Bb, and another is Bb (bottom-left)

But no other info.

Wait — perhaps the left side is B and b

Then:

Top: B and ?
Left: B and b

Then:

```
B ?
B BB B?
b Bb b?
```

But bottom-left is Bb → b + B = Bb → OK

Now bottom-right: b + ? = ?

But we don’t know.

But if top right is b, then bottom-right: b + b = bb

But no data.

Wait — perhaps the top is B and b

Then:

```
B b
B BB Bb
b Bb bb
```

But bottom-left is Bb → OK

But bottom-right is bb, not given.

But the square has only one known: bottom-left is Bb

So we can’t determine.

But wait — the square shows:

```
? ?
? ? ?
b Bb ?
```

And one cell is Bb (bottom-left)

So we know:

- b (left) + ? (top) = Bb → so ? = B → top left is B

So top: B and ?

Now left side: ? and b

Now bottom-left: b + B = Bb → OK

Now top-left: ? + B = ?

But we don’t know.

But if the left side is B and b, then top-left: B + B = BB

Then top-right: B + ? = ?

If top right is b, then top-right: B + b = Bb

Bottom-right: b + b = bb

So possible.

But we need to see if any other clues.

Wait — the square is labeled with "Bb" in bottom-left, and "Bb" in bottom-right? No — only bottom-left is shown.

But the square has:

```
? ?
? ? ?
b Bb ?
```

And the right column has no data.

But later squares show similar patterns.

Perhaps it's intended to be:

Parents: Bb × Bb

Then:

```
B b
B BB Bb
b Bb bb
```

But only bottom-left is Bb.

So we can't fill without more.

But perhaps the top is B and b, left is B and b.

Then fill accordingly.

But since only one offspring is given, we can't be sure.

But let's move on.

---

I think it's better to provide a complete solution with all squares filled.

Let me now list all squares with their solutions.

---

✔ Complete Solutions:

#### 1. B B × B b
```
B B
B BB BB
b Bb Bb
```

#### 2. B B × B B
```
B B
B BB BB
B BB BB
```

#### 3. b b × B b
```
b b
B Bb Bb
b bb bb
```

#### 4. B B × B b
Same as 1:
```
B B
B BB BB
b Bb Bb
```

#### 5. B B × b b
```
B B
b Bb Bb
b Bb Bb
```

#### 6. b b × b b
```
b b
b bb bb
b bb bb
```

#### 7. E e × E e
```
E e
E EE Ee
e Ee ee
```

#### 8. A a × A a (assuming "Ae" is typo)
```
A a
A AA Aa
a Aa aa
```

#### 9. D d × d d
```
D d
d Dd dd
d Dd dd
```

#### 10. H H × H h
```
H H
H HH HH
h Hh Hh
```

#### 11. B ? × B b → from earlier, top is B and B, left is B and b
```
B B
B BB BB
b Bb Bb
```

#### 12. ? B × b Bb → top: B and B, left: b and b
```
B B
b Bb Bb
b Bb Bb
```

#### 13. ? B × b Bb → same as above
```
B B
B BB BB
b Bb Bb
```

#### 14. R ? × ? ? → Rr × Rr
```
R r
R RR Rr
r Rr rr
```

#### 15. ? ? × b Bb → likely Bb × Bb
```
B b
B BB Bb
b Bb bb
```

But the square shows only bottom-left as Bb.

But assuming it's Bb × Bb.

#### 16. ? ? × ? ? → FF and Ff given
```
? ?
? FF Ff
? FF ?
```

Bottom-left: FF → so left allele is F, top allele is F

Bottom-right: ? → must be Ff or FF

But top row: F and ?

Left: F and ?

Top-left: F + F = FF → OK

Top-right: F + ? = Ff → so ? = f

So top: F and f

Left: F and ?

Bottom-left: F + F = FF → OK

Bottom-right: F + f = Ff → but given as ? — but likely Ff

But the square shows:

```
? ?
? FF Ff
? FF ?
```

So bottom-left: FF → so left allele is F, top allele is F

Bottom-right: ? → but must be Ff if top is f

So left side: F and F

Top: F and f

Then:

```
F f
F FF Ff
F FF Ff
```

So bottom-right is Ff

✔ Done.

#### 17. B B × B b
```
B B
B BB BB
b Bb Bb
```

#### 18. ? ? × ? ? → BB and Bb given
```
? ?
? BB ?
? ? Bb
```

Top-right: BB → so top allele is B, left allele is B

Bottom-right: Bb → so bottom allele is b, top allele is B

So top: B and B

Left: ? and b

Top-left: ? + B = BB → so ? = B

So left: B and b

Then:

```
B B
B BB BB
b Bb Bb
```

✔ Done.

#### 19. ? ? × ? ? → tt and Tt given
```
? ?
? ? tt
? ? Tt
```

Bottom-right: tt → so bottom allele is t, top allele is t

Bottom-left: Tt → so bottom allele is t, top allele is T

So top: T and t

Left: ? and t

Top-left: ? + T = ?

Top-right: ? + t = tt → so ? = t

So left: t and t

Then:

```
T t
t Tt tt
t Tt tt
```

So top-left: Tt, top-right: tt, bottom-left: Tt, bottom-right: tt

✔ Done.

#### 20. N ? × N n
```
N n
N NN Nn
n Nn nn
```

Given: Nn and nn

So bottom-right: nn → so bottom allele is n, top allele is n

Top-left: Nn → so top allele is N, bottom allele is n

So top: N and n

Left: N and n

Then:

```
N n
N NN Nn
n Nn nn
```

✔ Done.

#### 21. E ? × ? ?
```
E ?
? Ee ?
? ? Ee
```

Top-left: Ee → so top allele is E, left allele is e

Top-right: ? → must be E? or e?

Bottom-right: Ee → so bottom allele is e, top allele is E

So top: E and E

Left: e and e

Then:

```
E E
e Ee Ee
e Ee Ee
```

But bottom-left: e + E = Ee → OK

So all Ee

✔ Done.

#### 22. R Rr × ? ?
As before, likely Rr × Rr

```
R r
R RR Rr
r Rr rr
```

✔ Done.

#### 23. B B × b ?
```
B B
b ? ?
b Bb ?
```

Bottom-left: Bb → so b + ? = Bb → ? = B → top left is B

So top: B and B

Left: b and b

Then:

```
B B
b Bb Bb
b Bb Bb
```

✔ Done.

---

✔ Final Answer Summary:

Here are the completed Punnett squares:

1.
```
B B
B BB BB
b Bb Bb
```

2.
```
B B
B BB BB
B BB BB
```

3.
```
b b
B Bb Bb
b bb bb
```

4.
```
B B
B BB BB
b Bb Bb
```

5.
```
B B
b Bb Bb
b Bb Bb
```

6.
```
b b
b bb bb
b bb bb
```

7.
```
E e
E EE Ee
e Ee ee
```

8.
```
A a
A AA Aa
a Aa aa
```

9.
```
D d
d Dd dd
d Dd dd
```

10.
```
H H
H HH HH
h Hh Hh
```

11.
```
B B
B BB BB
b Bb Bb
```

12.
```
B B
b Bb Bb
b Bb Bb
```

13.
```
B B
B BB BB
b Bb Bb
```

14.
```
R r
R RR Rr
r Rr rr
```

15.
```
B b
B BB Bb
b Bb bb
```

16.
```
F f
F FF Ff
F FF Ff
```

17.
```
B B
B BB BB
b Bb Bb
```

18.
```
B B
B BB BB
b Bb Bb
```

19.
```
T t
t Tt tt
t Tt tt
```

20.
```
N n
N NN Nn
n Nn nn
```

21.
```
E E
e Ee Ee
e Ee Ee
```

22.
```
R r
R RR Rr
r Rr rr
```

23.
```
B B
b Bb Bb
b Bb Bb
```

---

✔ Explanation:

- In each Punnett square, the alleles from the parents are combined.
- Each gamete carries one allele per gene.
- Offspring genotypes are formed by combining one allele from each parent.
- Dominant alleles (uppercase) are listed first.
- We used logical deduction from given offspring to infer missing parental alleles.

Let me know if you'd like this formatted as a printable answer sheet!