Question
In humans, curly hair is dominant over straight hair. Which cross below has the correct probabilities listed?
Responses
A a woman heterozygous for hair curl, a man heterozygous for hair curl will produce 25% straight hair, 75% curly haira woman heterozygous for hair curl, a man heterozygous for hair curl will produce 25% straight hair, 75% curly hair
B a woman homozygous recessive for hair curl, a man homozygous recessive for hair curl will produce: 100% curly haira woman homozygous recessive for hair curl, a man homozygous recessive for hair curl will produce: 100% curly hair
C a woman heterozygous for hair curl, a man homozygous recessive for hair curl will produce: 75% straight hair, 25% curly haira woman heterozygous for hair curl, a man homozygous recessive for hair curl will produce: 75% straight hair, 25% curly hair
D a woman homozygous dominant for hair curl, a man homozygous recessive for hair curl will produce: 50% straight hair & 50% curly hair
Responses
A a woman heterozygous for hair curl, a man heterozygous for hair curl will produce 25% straight hair, 75% curly haira woman heterozygous for hair curl, a man heterozygous for hair curl will produce 25% straight hair, 75% curly hair
B a woman homozygous recessive for hair curl, a man homozygous recessive for hair curl will produce: 100% curly haira woman homozygous recessive for hair curl, a man homozygous recessive for hair curl will produce: 100% curly hair
C a woman heterozygous for hair curl, a man homozygous recessive for hair curl will produce: 75% straight hair, 25% curly haira woman heterozygous for hair curl, a man homozygous recessive for hair curl will produce: 75% straight hair, 25% curly hair
D a woman homozygous dominant for hair curl, a man homozygous recessive for hair curl will produce: 50% straight hair & 50% curly hair
Answers
GPT-4o mini
To determine the correct probabilities for the crosses involving curly hair (C, dominant) and straight hair (c, recessive), we can break down each option:
1. **A**: A woman heterozygous (Cc) for hair curl crossed with a man heterozygous (Cc) for hair curl.
- Possible gametes: C or c for both parents.
- Punnett square:
```
C | c
---------------
C | CC | Cc
---------------
c | Cc | cc
```
- Offspring genotypes: 1 CC, 2 Cc, 1 cc.
- Phenotype probabilities: 3 curly (CC or Cc) and 1 straight (cc), which is 75% curly and 25% straight.
- **Option A is correct**.
2. **B**: A woman homozygous recessive (cc) crossed with a man homozygous recessive (cc).
- All offspring will be cc.
- Phenotype probability: 100% straight hair.
- **Option B is incorrect**.
3. **C**: A woman heterozygous (Cc) crossed with a man homozygous recessive (cc).
- Possible gametes: C or c for the woman, only c for the man.
- Punnett square:
```
C | c
---------------
c | Cc | cc
```
- Offspring genotypes: 1 Cc and 1 cc.
- Phenotype probabilities: 1 curly (Cc) and 1 straight (cc), which is 50% curly and 50% straight.
- **Option C is incorrect**.
4. **D**: A woman homozygous dominant (CC) crossed with a man homozygous recessive (cc).
- Possible gametes: C for the woman, only c for the man.
- Punnett square:
```
C | C
---------------
c | Cc | Cc
```
- Offspring genotype: 100% Cc.
- Phenotype probability: 100% curly hair.
- **Option D is incorrect**.
**Conclusion**: The correct response is **A: a woman heterozygous for hair curl, a man heterozygous for hair curl will produce 25% straight hair, 75% curly hair**.
1. **A**: A woman heterozygous (Cc) for hair curl crossed with a man heterozygous (Cc) for hair curl.
- Possible gametes: C or c for both parents.
- Punnett square:
```
C | c
---------------
C | CC | Cc
---------------
c | Cc | cc
```
- Offspring genotypes: 1 CC, 2 Cc, 1 cc.
- Phenotype probabilities: 3 curly (CC or Cc) and 1 straight (cc), which is 75% curly and 25% straight.
- **Option A is correct**.
2. **B**: A woman homozygous recessive (cc) crossed with a man homozygous recessive (cc).
- All offspring will be cc.
- Phenotype probability: 100% straight hair.
- **Option B is incorrect**.
3. **C**: A woman heterozygous (Cc) crossed with a man homozygous recessive (cc).
- Possible gametes: C or c for the woman, only c for the man.
- Punnett square:
```
C | c
---------------
c | Cc | cc
```
- Offspring genotypes: 1 Cc and 1 cc.
- Phenotype probabilities: 1 curly (Cc) and 1 straight (cc), which is 50% curly and 50% straight.
- **Option C is incorrect**.
4. **D**: A woman homozygous dominant (CC) crossed with a man homozygous recessive (cc).
- Possible gametes: C for the woman, only c for the man.
- Punnett square:
```
C | C
---------------
c | Cc | Cc
```
- Offspring genotype: 100% Cc.
- Phenotype probability: 100% curly hair.
- **Option D is incorrect**.
**Conclusion**: The correct response is **A: a woman heterozygous for hair curl, a man heterozygous for hair curl will produce 25% straight hair, 75% curly hair**.