The schematic representation below indicates a cross between a heterozygous black cow and a homozygous recessive white bull - NSC Agricultural Sciences - Question 4 - 2016 - Paper 2
Question 4
The schematic representation below indicates a cross between a heterozygous black cow and a homozygous recessive white bull. Black (B) is the complete dominant chara... show full transcript
Worked Solution & Example Answer:The schematic representation below indicates a cross between a heterozygous black cow and a homozygous recessive white bull - NSC Agricultural Sciences - Question 4 - 2016 - Paper 2
Step 1
Identify the genotype of the: Parent black cow
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Answer
The parent black cow is heterozygous for the black phenotype. Therefore, the genotype is Bb (where B represents the dominant black gene and b represents the recessive white gene).
Step 2
Identify the genotype of the: Parent white bull
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Answer
The parent white bull is homozygous recessive, and its genotype is bb because it only carries the recessive white alleles.
Step 3
Determine the phenotype of the F2 offspring.
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Answer
When the F1 generation (which consists of both Bb and bb individuals) is crossed with the parent bull (Bb), the F2 generation will exhibit the phenotype of 50% black (from Bb) and 50% white (from bb).
Step 4
Use the Punnett square method to illustrate the genotype of the F1 generation.
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To determine the genotype, we can set up a Punnett square:
B | b
---------------
b | Bb | bb
---------------
b | Bb | bb
From this Punnett square, we can see that the genotypes of the F1 generation are 50% Bb and 50% bb.
