Question
Coat colour in cattle is inherited in a very similar way to blood groups in humans. The gene for coat colour has two codominant alleles:
Table 2.1 shows the genotypes and phenotypes of different coat colours seen in a herd of cattle.
Table 2.1
(a) (i) Explain the term codominance.
(ii) A farmer crossed several roan coloured cows with a roan coloured bull.
Complete the genetic diagram to show the ratio of expected phenotypes among the offspring.
phenotypic ratio …………………………………………………………………………………………………
(b) A farmer has a herd of cows that produce milk. The farmer wants to improve the milk yield of the herd by using artificial selection (selective breeding). The farmer buys semen (fluid containing sperm) to inseminate the cows artificially.
(i) Describe how the farmer could improve the milk yield of the cows using artificial selection.
(ii) Suggest one useful feature, other than milk yield and coat colour, which a farmer might wish to develop in a herd of cows.
(c) Milk yield can also be increased by injecting cows with the hormone bovine somatotropin (BST).
Explain why there may be concerns about the use of this hormone to increase milk yield.
Answer/Explanation
Ans:
(a) (i) both alleles are expressed ;
neither allele is dominant/recessive to the other ;
the phenotype of the heterozygote is intermediate ;
(ii) 
(b) (i) cows with best milk yield chosen ;
bull linked to cows with high milk yield chosen ;
these are mated/ artificial insemination used/AI used ;
offspring checked/ chosen for improved milk yield ;
these cows are then used to breed the next generation/AW/ process repeated ;
(ii) resistance to disease ;
good temperament ;
milk quality / example ;
rapid/ fast growth/ development ;
meat quality / increase in meat quantity ; AVP ;
(c) 1 consumer concerns about hormones in the milk ;
2 possible effects on human health/ allergies / side effects ;
3 reference to animal welfare/ health of cattle ;
4 concerns about lack of consumer choice/unable to avoid consuming milk produced from cows which have been injected with BST ;
5 unnecessary when there is no shortage of milk / already an overproduction of milk ;
6 AVP ;
Question
Table shows some information about air pollution.
(a) Complete Table 5.1 by writing answers in the spaces indicated. [2]
(b) Explain how the increased greenhouse effect is thought to lead to global warming.
(c) Fig. 5.1 shows changes in the emissions of sulfur dioxide in Europe between 1880 and
2004.
(i) Use the information in Fig. 5.1 to describe the changes in the emissions of sulfur
dioxide in Europe between 1880 and 2004.
(ii) Describe the effects of acid rain on the environment.
(iii) Outline the methods that have been used to reduce the emissions of sulfur dioxide.
Answer/Explanation
Ans:
