AQA · GCSE · Biology
Course version: 8461 · Version from Sept 2018
Students should be able to explain the impact of selective breeding of…
Full specification wording
Selective breeding: Students should be able to explain the impact of selective breeding of food plants and domesticated animals.
Selective breeding is when humans choose organisms with desired characteristics and breed them together.
Checked against the AQA 8461 specification (opens in a new tab) on .
- Point 1 of 9
Study notes
From the checked teaching notes for this specification point.
The idea
Selective breeding is when humans choose organisms with desired characteristics and breed them together. Over many generations the useful alleles become more common, so food plants may give higher yields, better disease resistance or improved taste, and domesticated animals may produce more milk, meat or wool or have a calmer temperament. A useful method is to identify the best individuals, breed them, then repeat with their best offspring. The impact includes reliable food supplies and improved productivity, but also reduced genetic variation, which makes populations vulnerable to new diseases, and possible welfare problems in animals bred for extreme features.
What earns the marks
- States that humans choose organisms with desired characteristics to breed together.
- Explains that useful alleles become more common over many generations.
- Gives examples of desired characteristics in food plants, such as yield, disease resistance or taste.
- Gives examples of desired characteristics in domesticated animals, such as milk yield, meat yield or temperament.
- Explains a negative impact such as reduced genetic variation or welfare problems.
Common mistakes and how to put them right
Confusing selective breeding with genetic engineering.
Put it right by noting that selective breeding chooses existing variation, while genetic engineering transfers genes directly.
Thinking selective breeding creates new alleles.
Put it right by explaining it increases the frequency of existing useful alleles.
Ignoring disadvantages; correct this by including reduced genetic variation or welfare issues.
Exam tips
- Name the desired characteristic and the organism when giving an example.
- Include both a benefit and a drawback to show balanced understanding.
- Use the phrase over many generations to show the timescale of selective breeding.
Try the lesson
The start of the Selective breeding: Students should be able to explain the impact of selective breeding of food plants and domesticated animals. lesson, made from checked teaching notes for this specification point.
Have a go first
A farmer has selectively bred a herd of cows over many generations to produce high yields of milk. What is a potential negative impact of this selective breeding process?
Listen
Selective breeding is when humans choose organisms with desired characteristics and breed them together. Over many generations the useful alleles become more common, so food plants may give higher yields, better disease resistance or improved taste, and domesticated animals may produce more milk, meat or wool or have a calmer temperament. A useful method is to identify the best individuals, breed them, then repeat with their best offspring. The impact includes reliable food supplies and improved productivity, but also reduced genetic variation, which makes populations vulnerable to new diseases, and possible welfare problems in animals bred for extreme features. A strong answer earns marks for these points. States that humans choose organisms with desired characteristics to breed together. Explains that useful alleles become more common over many generations. Gives examples of desired characteristics in food plants, such as yield, disease resistance or taste. Gives examples of desired characteristics in domesticated animals, such as milk yield, meat yield or temperament. A common slip: Confusing selective breeding with genetic engineering. Instead, noting that selective breeding chooses existing variation, while genetic engineering transfers genes directly. Exam tip: Name the desired characteristic and the organism when giving an example.
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