Photo AI
The diagram shows crosses in a breeding programme involving different breeds of sheep - Scottish Highers Biology - Question 9 - 2018
Question 9
The diagram shows crosses in a breeding programme involving different breeds of sheep. (P) Scottish Blackface female × Border Leicester male ... show full transcript
Worked Solution & Example Answer:The diagram shows crosses in a breeding programme involving different breeds of sheep - Scottish Highers Biology - Question 9 - 2018
Step 1
Suggest a reason why breeding programmes such as this include crossbreeding.
Answer
Breeding programmes such as this include crossbreeding to improve the characteristics or traits of the offspring. Crossbreeds may have enhanced traits from both parent breeds, which can lead to better overall qualities in the lambs, such as increased hardiness or productivity.
Step 2
Explain why Greyface sheep are produced by crossbreeding Scottish Blackfaces with Border Leicesters instead of breeding F₁ Greyface sheep together.
Answer
Greyface sheep are produced through crossbreeding to achieve greater genetic variation in the F₁ generation. This genetic variation can result in better traits in the offspring, whereas breeding F₁ Greyface sheep together may result in less diverse traits, limiting the benefits that can be gained from hybrid vigor.
Step 3
Step 4
Explain the importance of selecting a Suffolk male homozygous for the desired dominant characteristic.
Answer
Selecting a Suffolk male that is homozygous for the desired dominant characteristic is important because it ensures a higher chance of offspring exhibiting that characteristic. This is crucial for uniformity and predictability in the traits of the commercial lambs.
Step 5
State why inbreeding could cause an increase in the number of lambs born with this condition.
Answer
Inbreeding can lead to an accumulation of recessive deleterious alleles, increasing the likelihood of expressing harmful traits such as Spider lamb syndrome. When closely related animals breed, the chance of inheriting the same recessive alleles from both parents increases, leading to a higher incidence of the condition.