Connect adaptation to reproductive chance
A helpful feature changes reproductive chances only in its stated environment.
Exam scope and assessment notes
Mapped to the named 0973 section using teaching from the corresponding single-science course. A 0973-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. This qualification reports two grades on the 9–1 scale; confirm the entry route for your zone and exam series.
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 does “greater chance of reproduction” mean here?
What you will learn
- Compare reproductive outcomes in a stated environment
- Distinguish survival from reproduction
Original selection schematic. Population counts and scenarios are supplied teaching models; they are not field observations.
| Stage or record | Meaning |
|---|---|
| Pale group with offspring | 14 of 20 = 70% |
| Dark group with offspring | 8 of 20 = 40% |
| Measured outcome | Reproduction during the stated period |
| Limit | A single context does not predict every habitat |
Compare reproductive outcomes in a stated environment
Individuals that are better adapted to one environment have a greater chance of reproducing there, relative to others in the same population. “Greater chance” is comparative and conditional: it does not mean every individual with the feature survives, or that the feature is useful in every place.
In an invented grassland, the case states that pale fur is inherited and makes a small mammal less visible to a predator against pale soil. If pale individuals are less often detected and consequently leave more offspring in that grassland, the feature is associated with greater reproductive success in the stated context.
Distinguish survival from reproduction
Survival and reproduction are different measurements. An individual may survive an observation period but leave no offspring; another may reproduce before later dying. To support a natural-selection explanation, compare the reproductive contribution of groups, not only a one-time survival count. Keep starting group sizes and observation times comparable.
The word adapted means suited to the stated environment through a feature and its effect; it is not a synonym for strongest or perfect. Habitat, predator behaviour, food, disease and chance can change outcomes. Describe the mechanism supported by the case and avoid extending a local advantage to every environment or future generation.
Sources for this lesson
Pause and explain
What should be measured to compare reproductive success?
Worked example
In an invented grassland, 20 pale and 20 dark mammals are observed. The case states pale fur is inherited and reduces detection; later, 14 pale and 8 dark individuals have offspring. Compare the fractions.
Show the worked solution
- Calculate the reproductive fractions: 14/20 and 8/20.
- The fractions are 70% and 40%; compare them within the stated case.
Answer The recorded fractions are 70% for pale and 40% for dark individuals. This supports greater reproductive success for pale individuals in this case, but does not show every pale individual reproduced or prove the feature helps elsewhere.
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.
Use 14 reproducing pale mammals from 20 and 8 reproducing dark mammals from 20. Find the difference in recorded percentages.
Give me a hint
Find both proportions with denominator 20.
Compare my reasoning
- 14/20 = 70%; 8/20 = 40%.
- Subtract 40% from 70%.
The difference is 30 percentage points in this record; it does not guarantee future outcomes.
Look for these in your work
- Both group percentages
- Difference named accurately
A dark insect survives longer in a laboratory tray, but no offspring are counted. Can this alone establish greater reproductive success? Explain.
Give me a hint
Check whether the measured outcome is survival or reproduction.
Compare my reasoning
- The record measures time alive, not offspring.
- Reproductive contribution needs offspring information.
No. It may establish a survival difference under the tray conditions, but it does not show which group left more offspring.
Look for these in your work
- Outcome distinguished
- Missing evidence named
In a dry year, a deep-rooted plant group produces more seeds in a controlled comparison. In a flooded year, a shallow-rooted group produces more. Explain how both observations can be consistent with natural selection.
Give me a hint
Keep each environment separate and link the supplied inherited features to offspring records.
Compare my reasoning
- The reproductive ranking changes with water conditions.
- Selection is conditional; neither root feature is universally best.
Both records can be consistent because different environmental conditions change reproductive chances. The data suggest context-specific advantages, subject to inheritance and study-design evidence.
Look for these in your work
- Context-specific outcomes
- No universal ranking
Common mistakes
- Equating survival with reproduction
- Claiming all individuals with the feature reproduce
- Treating context-dependent advantage as universal
What can you explain now?
What should be measured to compare reproductive success?
Compare with the explanation
Offspring contributions for comparable groups
Reproduction is the outcome being compared.
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Make it stick
Without your notes, compare reproductive outcomes in a stated environment and distinguish survival from reproduction. 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.