Describe artificial selection
Explain how humans choose parents with desired phenotypes and select offspring over generations.
A Level; Cambridge International Biology 9700, 2028–2030. Written answers and calculations are self-checked; this is not fieldwork or practical-skills certification.
Before you begin
- Populations contain inherited variation, and alleles can be transmitted from parents to offspring.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Who chooses the parents in artificial selection?
What you will learn
- Describe selection of parents with desirable characteristics
- Explain repeated breeding and offspring selection as artificial selection
Original selection schematic. Population counts and scenarios are supplied teaching models; they are not field observations.
| Stage or record | Meaning |
|---|---|
| Breeding goal | Larger measured seed mass |
| Selected parents | 8 of 40 plants |
| Human role | Chooses parents for the stated feature |
| Next steps | Cross parents; assess and choose offspring |
Build the evolutionary explanation
In artificial selection, humans choose individuals with desired phenotypes to breed. Their offspring are assessed, and selected offspring are bred in subsequent generations. If the trait has an inherited component, alleles associated with it can become more frequent. Inbreeding can increase homozygosity; crossing distinct lines can produce hybrids with useful combinations, but outcomes depend on the breeding design.
Interpret data with care
Selection is imposed by breeders rather than by survival under a natural environment. A selected phenotype may have environmental as well as genetic causes, so breeding records and offspring performance matter.
Pause and explain
Compare the source of selection in natural selection and selective breeding.
Worked example
A breeder repeatedly chooses cattle with high milk yield as parents. What process is being used?
Show the worked solution
- Humans choose which individuals reproduce.
- The selected trait is favoured across generations.
Answer Artificial selection.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Outline how breeders can increase a desired inherited crop trait over several generations.
Give me a hint
Identify the population-level variable and sequence the mechanism.
Compare my reasoning
- Choose parents with the trait.
- Breed selected offspring repeatedly.
Breeders select plants showing the desired phenotype, cross them and assess offspring. They use selected offspring as parents in later generations, increasing relevant alleles if the trait is inherited.
Look for these in your work
- Population process identified
- Cause and consequence linked
A breeder selects the largest plants from one season without measuring offspring. What limitation should be considered?
Give me a hint
Use the supplied sample or condition to justify the conclusion.
Compare my reasoning
- Plant size may depend on environment.
- The chosen phenotype may not be inherited strongly.
Large size may reflect growing conditions rather than inherited alleles. Offspring testing across controlled conditions would help estimate the inherited component.
Look for these in your work
- Evidence interpreted
- Assumptions stated
Compare the source of selection in natural selection and selective breeding.
Give me a hint
Apply the population model to the new example and qualify its limits.
Compare my reasoning
- Environmental conditions affect reproductive success naturally.
- Humans choose parents in artificial selection.
Natural selection results from differential survival and reproduction in an environment. Artificial selection occurs when people deliberately choose which individuals breed.
Look for these in your work
- Model applied
- Limits preserved
Common mistakes
- Assuming a desired phenotype is entirely genetic
- Confusing natural selection with deliberate breeding
What can you explain now?
Who chooses the parents in artificial selection?
Compare with the explanation
Humans or breeders
They choose individuals with desired phenotypes to reproduce.
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Make it stick
How do breeders change a trait over successive generations?
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.