Solved Punnett Square Practice Worksheet Part A: Vocabulary ... - Free Printable

Punnett Square Practice Worksheet Solution

#### Part A: Vocabulary
Match the definitions on the left with the terms on the right.

1. Genotypes made of the same alleles
- Definition: Genotypes that have two identical alleles for a trait (e.g., AA, aa).
- Match: D. homozygous

2. Different forms of genes for a single trait
- Definition: Variants of a gene that control the same trait (e.g., A and a).
- Match: A. alleles

3. Gene that is always expressed
- Definition: A dominant allele is expressed even if only one copy is present (heterozygous or homozygous dominant).
- Match: B. dominant

4. Gene that is expressed only in the homozygous state
- Definition: A recessive allele is expressed only when two copies are present (homozygous recessive).
- Match: E. recessive

5. Genotypes made of two different alleles
- Definition: Genotypes that have two different alleles for a trait (e.g., Aa, Bb).
- Match: C. heterozygous

---

#### Part B: Circle the choices that are examples of each of those words.

6. Homozygous dominant
- Definition: Genotypes with two identical dominant alleles (e.g., AA, TT).
- Examples: AA, TT

7. Homozygous recessive
- Definition: Genotypes with two identical recessive alleles (e.g., aa, tt).
- Examples: mm, uu, ww

8. Genotypes in which dominant gene must show
- Definition: Genotypes where the dominant allele is expressed (homozygous dominant or heterozygous).
- Examples: AA, Dd, EE, Ff, Jj, RR, Ss

9. Genotypes in which recessive gene must show
- Definition: Genotypes where the recessive allele is expressed (homozygous recessive).
- Examples: aa, kk, oo, tt

---

#### Part C: Punnett Squares

10. Examine the following Punnett squares and circle those that are correct.

- First Punnett Square:
```
D d
d Dd dd
d Dd dd
```
- Correct. Each box contains the correct combination of alleles.

- Second Punnett Square:
```
D D
d Dd Dd
d Dd Dd
```
- Incorrect. The top row should be "D" and "d," not "D" and "D."

- Third Punnett Square:
```
A a
A AA Aa
a Aa aa
```
- Correct. Each box contains the correct combination of alleles.

- Fourth Punnett Square:
```
A a
A Aa Aa
a Aa aa
```
- Incorrect. The top row should be "A" and "a," but the combinations in the boxes are incorrect.

Correct Punnett Squares:
- First Punnett Square
- Third Punnett Square

11. What do the letters on the outside of the Punnett square stand for?
- The letters on the outside represent the alleles of the parents involved in the cross.

12. What do the letters on the inside of the Punnett square stand for?
- The letters on the inside represent the genotypes of the offspring resulting from the cross.

---

#### Part D: Complete the Punnett squares showing different crosses.

13. In corn plants, normal height (N) is dominant to short height (n). Complete these four Punnett squares showing different crosses. Then, circle all of the homozygous dominant offspring. Put an X through all the heterozygous offspring. Leave all the homozygous recessive offspring unshaded.

- Cross 1: N x n
```
N n
N NN Nn
n Nn nn
```
- Homozygous dominant: NN
- Heterozygous: Nn, Nn
- Homozygous recessive: nn

- Cross 2: N x N
```
N N
N NN NN
N NN NN
```
- Homozygous dominant: NN, NN, NN, NN
- No heterozygous or homozygous recessive offspring.

- Cross 3: n x n
```
n n
n nn nn
n nn nn
```
- Homozygous recessive: nn, nn, nn, nn
- No heterozygous or homozygous dominant offspring.

- Cross 4: N x n
```
N n
N NN Nn
n Nn nn
```
- Homozygous dominant: NN
- Heterozygous: Nn, Nn
- Homozygous recessive: nn

---

Final Answer:

- Part A:
1. D
2. A
3. B
4. E
5. C

- Part B:
6. AA, TT
7. mm, uu, ww
8. AA, Dd, EE, Ff, Jj, RR, Ss
9. aa, kk, oo, tt

- Part C:
10. First and Third Punnett Squares
11. Alleles of the parents
12. Genotypes of the offspring

- Part D:
- Cross 1:
```
N n
N NN Nn
n Nn nn
```
- Circle: NN
- X: Nn, Nn
- Unshaded: nn

- Cross 2:
```
N N
N NN NN
N NN NN
```
- Circle: NN, NN, NN, NN

- Cross 3:
```
n n
n nn nn
n nn nn
```
- Unshaded: nn, nn, nn, nn

- Cross 4:
```
N n
N NN Nn
n Nn nn
```
- Circle: NN
- X: Nn, Nn
- Unshaded: nn

Final Answer Boxed:
\boxed{
\text{See detailed solutions above.}
}