AQA · GCSE · Biology
Course version: 8461 · Version from Sept 2018
Selective breeding involves choosing parents with the desired…
Full specification wording
Selective breeding: Selective breeding involves choosing parents with the desired characteristic from a mixed population.
In a mixed population, individuals vary in their characteristics because they have different combinations of alleles.
Checked against the AQA 8461 specification (opens in a new tab) on .
- Point 4 of 9
- 3 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
In a mixed population, individuals vary in their characteristics because they have different combinations of alleles. Selective breeding starts by identifying the individuals that show the desired characteristic, such as high milk yield in cattle or large fruit size in tomato plants. These individuals are chosen as parents, while those without the desired characteristic are not allowed to breed. Choosing from a mixed population is essential because the variation provides the raw material for selection. For example, a farmer measures milk yield in a herd, records the highest producers, and selects those cows and a high-yielding bull for breeding. The chosen parents must be able to pass the characteristic to their offspring.
What earns the marks
- A mixed population contains individuals with a range of characteristics due to genetic variation.
- Humans identify and choose individuals that show the desired characteristic.
- Individuals without the desired characteristic are not selected as parents.
- The desired characteristic must be heritable so that it can be passed to offspring.
- Selection from a mixed population relies on existing genetic variation rather than creating new alleles.
Common mistakes and how to put them right
Thinking all individuals in a population are identical.
Put it right by stating that a mixed population shows genetic variation.
Selecting parents that do not show the desired characteristic.
Put it right by choosing only individuals that clearly display the desired trait.
Forgetting that the characteristic must be inherited.
Put it right by stating that selected parents pass alleles for the trait to their offspring.
Exam tips
- Name the desired characteristic and state how it is measured or observed, for example milk yield in litres per day.
- Use the phrase 'mixed population' and explain that variation means some individuals are better suited to the breeding aim.
- Make clear that humans, not the environment, choose which individuals become parents.
Try the lesson
The start of the Selective breeding: Selective breeding involves choosing parents with the desired characteristic from a mixed population. lesson, made from checked teaching notes for this specification point.
Have a go first
In selective breeding, which animals are chosen to be the parents of the next generation?
Listen
In a mixed population, individuals vary in their characteristics because they have different combinations of alleles. Selective breeding starts by identifying the individuals that show the desired characteristic, such as high milk yield in cattle or large fruit size in tomato plants. These individuals are chosen as parents, while those without the desired characteristic are not allowed to breed. Choosing from a mixed population is essential because the variation provides the raw material for selection. For example, a farmer measures milk yield in a herd, records the highest producers, and selects those cows and a high-yielding bull for breeding. The chosen parents must be able to pass the characteristic to their offspring. A strong answer earns marks for these points. A mixed population contains individuals with a range of characteristics due to genetic variation. Humans identify and choose individuals that show the desired characteristic. Individuals without the desired characteristic are not selected as parents. The desired characteristic must be heritable so that it can be passed to offspring. A common slip: Thinking all individuals in a population are identical. Instead, stating that a mixed population shows genetic variation. Exam tip: Name the desired characteristic and state how it is measured or observed, for example milk yield in litres per day.
See it
Key words
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Genetic variation within populations
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Selection of parents by humans
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Heritability of desired characteristics
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See every definition
- Genetic variation within populations
- Individuals in a mixed population vary in their characteristics because they have different combinations of alleles.
- Selection of parents by humans
- Humans identify and choose individuals that show the desired characteristic as parents, while those without it are not allowed to breed.
- Heritability of desired characteristics
- The chosen parents must be able to pass the characteristic to their offspring.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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