Question
A cat breeder is trying to breed long-haired cats. The short-haired (N) allele is dominant. This particular breed of cat has one gene for long hair (n) that is recessive. The cat breeder crosses a homozygous dominant cat with a heterozygous cat.
How likely are they to get long-haired cats? Why?
A.
0%, the homozygous dominant cat will only pass on the gene for short hair and so the phenotype will be short hair for all of the offspring.
B.
25%, the offspring will inherit a long-haired allele from each parent and, therefore, one of four of the offspring will be long-haired.
C.
50%, the heterozygous cat will pass on the gene for long hair and so the phenotype will be long hair for half of the offspring.
D.
75%, three out four of the offpsring will inherit the dominant allele (N) from each parent and, therefore, one of four of the offspring will be long-haired.
How likely are they to get long-haired cats? Why?
A.
0%, the homozygous dominant cat will only pass on the gene for short hair and so the phenotype will be short hair for all of the offspring.
B.
25%, the offspring will inherit a long-haired allele from each parent and, therefore, one of four of the offspring will be long-haired.
C.
50%, the heterozygous cat will pass on the gene for long hair and so the phenotype will be long hair for half of the offspring.
D.
75%, three out four of the offpsring will inherit the dominant allele (N) from each parent and, therefore, one of four of the offspring will be long-haired.
Answers
GPT-4o mini
To determine the probability of getting long-haired cats from the given cross, we need to analyze the alleles involved.
1. The homozygous dominant cat has the genotype **NN** (two dominant short-haired alleles).
2. The heterozygous cat has the genotype **Nn** (one dominant short-haired allele and one recessive long-haired allele).
When these two cats are crossed, the possible genotypes of their offspring can be determined from a Punnett square:
| | N | N |
|----------|------|------|
| **N** | NN | NN |
| **n** | Nn | Nn |
From this Punnett square, we can see that the possible genotypes for the offspring are:
- **NN**: 2 offspring (100% short-haired)
- **Nn**: 2 offspring (50% short-haired, 50% long-haired)
Therefore, all of the offspring will display either an **NN** or **Nn** genotype:
- 100% of the offspring will be short-haired (NN)
- 50% of the offspring will be heterozygous (Nn) but still display the short-haired phenotype due to dominance.
Since none of the offspring can inherit two recessive alleles (nn), there will be **0%** long-haired cats.
So the correct answer is:
**A. 0%, the homozygous dominant cat will only pass on the gene for short hair and so the phenotype will be short hair for all of the offspring.**
1. The homozygous dominant cat has the genotype **NN** (two dominant short-haired alleles).
2. The heterozygous cat has the genotype **Nn** (one dominant short-haired allele and one recessive long-haired allele).
When these two cats are crossed, the possible genotypes of their offspring can be determined from a Punnett square:
| | N | N |
|----------|------|------|
| **N** | NN | NN |
| **n** | Nn | Nn |
From this Punnett square, we can see that the possible genotypes for the offspring are:
- **NN**: 2 offspring (100% short-haired)
- **Nn**: 2 offspring (50% short-haired, 50% long-haired)
Therefore, all of the offspring will display either an **NN** or **Nn** genotype:
- 100% of the offspring will be short-haired (NN)
- 50% of the offspring will be heterozygous (Nn) but still display the short-haired phenotype due to dominance.
Since none of the offspring can inherit two recessive alleles (nn), there will be **0%** long-haired cats.
So the correct answer is:
**A. 0%, the homozygous dominant cat will only pass on the gene for short hair and so the phenotype will be short hair for all of the offspring.**