In cats, coat colour and fur length are inherited characteristics - VCE - SSCE Biology - Question 8 - 2010 - Paper 1
Question 8
In cats, coat colour and fur length are inherited characteristics. The two genes involved are on different chromosomes and have the following alleles.
Coat colour: ... show full transcript
Worked Solution & Example Answer:In cats, coat colour and fur length are inherited characteristics - VCE - SSCE Biology - Question 8 - 2010 - Paper 1
Step 1
Determine the genotype of Felix.
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Answer
Felix has short black fur, which indicates that he must have at least one dominant allele for both traits. Therefore, his genotype could be either homozygous dominant (BB SS) or heterozygous (Bb SS).
Step 2
Identify the test cross subject.
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Answer
To determine Felix's exact genotype, Joyce should mate him with a female cat that is homozygous recessive for both traits. The genotype for this female cat would be 'bb ss'.
Step 3
Determine the potential offspring genotypes.
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Answer
If Felix is homozygous dominant (BB SS), all offspring would display the dominant traits (black and short). If Felix is heterozygous (Bb SS), he would produce offspring with the following possible genotypes:
BB SS: black and short
Bb SS: black and short
bb SS: brown and short (only if Felix is Bb)
All offspring would show short fur due to the dominant allele (S).
Step 4
Conclusion regarding Felix's genotype.
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Answer
By observing the characteristics of the offspring, Joyce can determine if Felix is homozygous (all offspring black and short) or heterozygous (some offspring may be brown and short if he is Bb). Therefore, the correct answer is 'C. Bb Ss'.
