Selective breeding: Students should be able to explain the impact of selective breeding of food plants and domesticated animals.

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Q: Is this Selective breeding: Students should be able to explain the impact of selective breeding of food plants and domesticated animals. guide aligned to the AQA specification?

Yes. This guide is linked to the Selective breeding: Students should be able to explain the impact of selective breeding of food plants and domesticated animals. topic in the AQA GCSE specification.

Selective breeding is when humans choose organisms with desirable characteristics and breed them together, repeatedly over many generations.

Study notes

From the checked teaching notes for this specification point.

The idea

What earns the marks

Selective breeding involves choosing parents with desired characteristics and breeding them together over several generations.
In food plants, examples include selecting for higher yield, disease resistance or better flavour, which can improve food security.
In domesticated animals, examples include selecting for increased milk or meat production, or for temperament, which can benefit farmers.
A negative impact is reduced genetic variation, making populations more susceptible to disease or environmental change.
Another negative impact can be inherited health problems in some domesticated animals, such as breathing difficulties in certain breeds.

Common mistakes and how to put them right

Thinking selective breeding creates new alleles.
Put it right: It selects from existing variation, so no new alleles are produced.
Assuming selective breeding always benefits the organism.
Put it right: It benefits humans, but can harm the organism's health or reduce its genetic diversity.
Confusing selective breeding with genetic engineering.
Put it right: Selective breeding involves breeding existing organisms, whereas genetic engineering directly alters DNA.

Exam tips

Give at least one named example for a food plant and one for a domesticated animal to show understanding of both contexts.
Balance your answer by explaining both benefits, such as increased yield, and drawbacks, such as reduced genetic variation.
Use the term 'genetic variation' when explaining why selectively bred populations may be at greater risk from disease.

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 selectively breeds cows to produce the maximum amount of milk. What is a potential negative impact of this selective breeding over many generations?

Tip: press 1 to 4 to choose

Listen

Selective breeding is when humans choose organisms with desirable characteristics and breed them together, repeatedly over many generations. For food plants, farmers may select wheat with high yield or disease resistance; for domesticated animals, they may select cows that produce more milk or chickens that grow quickly. The impact is that the chosen features become more common in the population, so food production can increase. However, selective breeding reduces genetic variation, because only a few individuals are bred. This makes populations more vulnerable to new diseases or changes in the environment, and can cause health problems in some domesticated animals. A strong answer earns marks for these points. Selective breeding involves choosing parents with desired characteristics and breeding them together over several generations. In food plants, examples include selecting for higher yield, disease resistance or better flavour, which can improve food security. In domesticated animals, examples include selecting for increased milk or meat production, or for temperament, which can benefit farmers. A negative impact is reduced genetic variation, making populations more susceptible to disease or environmental change. A common slip: Thinking selective breeding creates new alleles. Instead, it selects from existing variation, so no new alleles are produced. Exam tip: Give at least one named example for a food plant and one for a domesticated animal to show understanding of both contexts.

See it

A flowchart running from top to bottom. The first box says humans choose organisms with desirable characteristics, which leads to breeding the chosen organisms together, then repeating over many generations. This leads to chosen features becoming more common in the population. From that box two outcomes branch out: one is that food production can increase, and the other is that genetic variation is reduced. The reduced genetic variation box then leads to two further outcomes: the population becomes more vulnerable to new diseases or environmental change, and inherited health problems can occur in some domesticated animals. — It shows the sequence of selective breeding and the resulting benefits and risks.

Label the diagram

Some boxes have lost their names. Pick the right name for each number.

The diagram again, with 3 boxes numbered instead of named. A flowchart running from top to bottom. The first box says humans choose organisms with desirable characteristics, which leads to breeding the chosen organisms together, then repeating over many generations. This leads to chosen features becoming more common in the population. From that box two outcomes branch out: one is that food production can increase, and the other is that genetic variation is reduced. The reduced genetic variation box then leads to two further outcomes: the population becomes more vulnerable to new diseases or environmental change, and inherited health problems can occur in some domesticated animals.

1Box 1
2Box 2
3Box 3

0 of 3 labelled

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