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A farmer received four pigs as a gift from a neighbour - NSC Agricultural Sciences - Question 4 - 2018 - Paper 2
Question 4
A farmer received four pigs as a gift from a neighbour. - One white female - One red female - Two red males The farmer decided to divide them into two breeding pai... show full transcript
Worked Solution & Example Answer:A farmer received four pigs as a gift from a neighbour - NSC Agricultural Sciences - Question 4 - 2018 - Paper 2
Step 1
Calculate the percentage of the offspring that are red in the F₂-generation of BREEDING PAIR 1
Answer
To determine the percentage of red offspring in the F₂-generation, we can use the offspring ratio from breeding pair 1, where 3 out of 4 piglets are red. The calculation for the percentage is: [ \text{Percentage of red offspring} = \left( \frac{3}{4} \right) \times 100 = 75% ]
Step 2
Use the Punnett square to determine the genotype of the F₁-generation offspring in BREEDING PAIR 2
Answer
The genotypes of the pigs in BREEDING PAIR 2 are a red male (DD or Dd) and a red female (Dd). Setting up the Punnett square, we can find:
[ \begin{array}{|c|c|c|} \hline & D & d \ \hline D & DD & Dd \ \hline D & DD & Dd \ \hline \end{array} ]
Thus, the genotypes of the F₁-generation offspring are:
- 50% DD (homozygous red)
- 50% Dd (heterozygous red)
Step 3
Determine the phenotypic ratio of the offspring in QUESTION 4.1.2
Answer
The phenotypic ratio can be determined from the genotypes calculated in the Punnett square. Since both DD and Dd express the red phenotype, we have a total of:
- 100% Red offspring Hence, the phenotypic ratio is: [ \text{Phenotypic ratio} = 1:0 \quad (100% \text{ red}) ]
Step 4
Step 5