AQA GCSE Biology (8461), Higher tier · Inheritance, variation and evolution › Variation and evolution
Practise Selective breeding. 11 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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Give two characteristics that farmers might choose when selectively breeding food crops or farm animals.
E.g. disease resistance in crops; high yield; animals that produce more meat or milk
All of these vegetables still belong to the same species. What does this tell you about them?
They can interbreed to produce fertile offspring
Give the name of the process in which humans choose organisms with desired characteristics and breed them together over many generations.
Selective breeding
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy5 marks
Humans have used selective breeding for thousands of years.
(a) What is selective breeding? Tick (✓) one box.[1]
Changing an organism's genome by adding a gene from another organism
Growing new plants from small groups of cells
Humans choosing parents with desired characteristics and breeding them together
The survival of the organisms best suited to their environment in the wild
(b) Give two characteristics that farmers might choose when selectively breeding food crops or farm animals.[2]
(c) The steps in selective breeding are given below, but they are in the wrong order. A Breed together the offspring that show the desired characteristic. B Choose parents with the desired characteristic from a mixed population. C Repeat over many generations until all the offspring show the characteristic. D Breed the chosen parents together. Write the letters in the correct order.[2]
Show the answer and mark scheme
(a)Answer: Humans choosing parents with desired characteristics and breeding them together
(b)Answer: E.g. disease resistance in crops; high yield; animals that produce more meat or milk
disease resistance (in food crops)
animals that produce more meat
animals that produce more milk
higher yield / bigger fruit or grain
(c)Answer: B, D, A, C
B first and C last
D before A
Question 2Medium6 marks
Cabbage, broccoli, cauliflower, kale and Brussels sprouts have all been produced by selective breeding from the same species of wild plant.
(a) Broccoli has very large flower heads. Describe how farmers produced broccoli from the wild plant.[3]
(b) All of these vegetables still belong to the same species. What does this tell you about them?[1]
(c) Plant breeders also select crops for disease resistance. Give two benefits of growing disease-resistant crops.[2]
Show the answer and mark scheme
(a)Answer: Chose wild plants with the largest flower heads and bred them together; chose the offspring with the largest flower heads and bred them; repeated this for many generations
choose plants with the largest flower heads
breed them together and select offspring with the largest flower heads (to breed)
repeat over many generations
(b)Answer: They can interbreed to produce fertile offspring
they can interbreed to produce fertile offspring
(c)Answer: Higher yields; less need for pesticides / fungicides, which saves money and harms the environment less
higher yield / less crop lost
less need to spray pesticides / fungicides
lower costs for the farmer
more reliable food supply / food security
Question 3Hard7 marks
Many breeds of dog have been produced by selective breeding. To keep the characteristics of a breed, breeders often mate closely related dogs. This is called inbreeding. In one breed, a large number of dogs have an inherited eye disorder caused by a recessive allele.
(a) Explain why inbreeding increases the chance that puppies will have a disorder caused by a recessive allele.[3]
(b) Explain why selective breeding reduces the genetic variation within a breed.[2]
(c) A test has been developed that shows whether a dog carries the allele for the eye disorder. Suggest how breeders could use the test to reduce the number of puppies born with the disorder.[2]
Show the answer and mark scheme
(a)Answer: Related dogs share many of the same alleles, so both parents are more likely to carry the same recessive allele; each puppy is then more likely to inherit two copies and be homozygous recessive
related dogs share many of the same alleles
so both parents are more likely to carry the (same) recessive allele
so puppies are more likely to inherit two copies / be homozygous recessive
(b)Answer: Only a few dogs with the chosen characteristics are bred, so other alleles are lost from the breed
only dogs with certain characteristics are used for breeding / only a few parents are used
so some alleles are lost / fewer different alleles in the breed
(c)Answer: Test dogs before breeding and never mate two carriers together; breed carriers only with dogs that do not carry the allele (or do not breed from carriers)
test dogs before breeding
do not mate two carriers together / only breed carriers with non-carriers / do not breed from carriers