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IGCSE · Cambridge (CIE) · 0654

Compare natural and artificial selection

Both processes involve inherited variation; the primary selection pressure differs.

Selection · Cambridge IGCSE 0654 · B17.2

Mapped to the named 0654 section using teaching from the corresponding single-science course. A 0654-specific review of every Core and Supplement objective is still in progress. Written practice is self-checked; it does not demonstrate supervised laboratory competence or award an official Cambridge grade.

Before you begin

  • Use the stated case, sample and assumptions. Diagrams and numerical records in this pathway are original teaching models; written answers are self-checked.

Work on paper. Try each question before revealing help, and explain why your method works.

Quick readiness check

What is the key difference between natural and artificial selection?

What you will learn

  • Compare environmental and human selection pressures
  • Identify the process from a described breeding or habitat context

Original selection schematic. Population counts and scenarios are supplied teaching models; they are not field observations.

Compare natural and artificial selectionOriginal schematic for this worked context. Trait, population and selection claims use only the supplied assumptions; stage labels are not measurements of every individual.Compare natural and artificial selection1Naturalenvironmental conditions affect reproductivechances.2Artificialpeople choose parents for a desired feature.3Sharedvariation, inheritance and reproduction; identifythe mechanism described.
Original schematic for this worked context. Trait, population and selection claims use only the supplied assumptions; stage labels are not measurements of every individual.
Selection evidence key
Stage or recordMeaning
Wild populationEnvironment affects relative reproduction
Breeding programmePeople choose parents and target
Shared basisInherited variation and offspring
Key questionWho or what changes reproductive contribution?

Compare environmental and human selection pressures

Natural selection occurs when environmental conditions influence the relative survival and reproduction of inherited variants. Competition for resources can be part of that context. Individuals better suited to the stated conditions have a greater chance of producing offspring, which may inherit associated alleles.

Artificial selection occurs when people deliberately choose organisms with desirable features as parents. The chosen parents are crossed; offspring showing the target feature are selected for later generations. The human-selected criterion could be crop seed size or a domesticated animal feature.

Identify the process from a described breeding or habitat context

Both processes depend on variation and reproduction, and both can alter how common inherited traits become over generations. Their key difference is not whether an environment exists—both happen in environments—but whether human choice of breeding parents is the primary selection mechanism described.

Humans can also affect natural selection by changing habitats, so identify what the question says is driving the reproductive difference. Do not call every change involving people artificial selection: a road may alter habitat without people choosing which organisms reproduce. Conversely, deliberate breeding is artificial selection even though the organisms also face environmental conditions.

Sources for this lesson

Pause and explain

A road changes habitat, but people do not choose organism parents. Is this automatically artificial selection?

Put the idea to work

Worked example

In one case, drought changes which wild plants leave more seeds. In another, a farmer chooses parents for seed size. Compare the selection process in each.

Show the worked solution
  1. For the wild population, identify the environmental condition affecting reproduction.
  2. For the crop, identify the human-selected parent criterion and repeated breeding step.

Answer Drought-related differential reproduction in a wild population describes natural selection if inherited variation and allele transmission are supported. The farmer’s deliberate parent choice describes artificial selection.

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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.

1 · Guided

Wild moth colour proportions shift as a habitat darkens and predator detection differs. What process may be involved, and what evidence links it to natural selection?

Give me a hint

The habitat is acting through environmental reproductive outcomes.

Compare my reasoning
  1. Natural selection is possible if colour variation is inherited.
  2. Compare reproduction and allele transmission across generations.

This may be natural selection if inherited colour differences are linked to differential reproduction in that habitat and associated alleles pass to offspring.

Look for these in your work

  • Process conditional
  • Evidence links named
2 · Independent

A breeder chooses parent dogs for a stated coat feature and selects offspring for the next mating. Identify the process and two steps.

Give me a hint

Human parent choice identifies the process.

Compare my reasoning
  1. The breeder selects parents for a desired feature.
  2. Offspring are assessed and selected for later breeding.

This is artificial selection: deliberate parent choice, crossing/mating, then offspring selection; repetition across generations continues the process.

Look for these in your work

  • Process and criterion
  • Offspring step
3 · Transfer

A conservation project releases a pesticide that changes insect survival, while a separate breeding programme chooses parents for pesticide tolerance. Compare carefully.

Give me a hint

One activity changes the environment; the other directly chooses breeding parents.

Compare my reasoning
  1. The pesticide may create an environmental selection pressure.
  2. The breeding team performs artificial selection only if it chooses parents and offspring.

The environmental change can contribute to natural selection among insects; deliberate choice of parents for tolerance is artificial selection. The description should not confuse exposure with parent choice.

Look for these in your work

  • Both mechanisms separated
  • Human selection criterion

Common mistakes

  • Defining artificial selection as any human presence
  • Claiming natural selection has no human-influenced environment
  • Ignoring shared inheritance and reproduction
Recall without your notes

What can you explain now?

A road changes habitat, but people do not choose organism parents. Is this automatically artificial selection?

Compare with the explanation

No; habitat change alone is not deliberate breeding

Artificial selection requires human choice of parents for desired features.

After trying it yourself, choose your next review. This is your self-assessment.

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Make it stick

Without your notes, compare environmental and human selection pressures and identify the process from a described breeding or habitat context. Explain the mechanism, use the given population or breeding records and state what the evidence does not establish.

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.

Keep learning Sciences — Co-ordinated (Double)

Course scope and assessment

This 2028–2029 pathway maps all 152 detailed subject-content sections in the published 0654 syllabus to original teaching and staged practice. It adapts teaching from the related single-science pathways and excludes clear 0610-only topics such as classification systems, human excretion, tropic responses, food supply, population dynamics, detailed pollution and biotechnology. Some explanations may include wider single-science context. A 0654-specific objective-by-objective review, Core/Supplement audit, human subject-teacher review, supervised laboratory experience and cumulative assessment remain in progress. Written practice is self-checked and does not predict an official grade. The 2025–2027 syllabus has not been reconciled here; choose the 2028–2029 syllabus only.

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