Grade 9 · Science
Explain natural selection from population evidence
Link heritable variation and differences in reproductive success to changes in a population over generations.
6 authored questions + worked example
Worked example
Before a drought, a plant population already has inherited differences in root depth. Which part of natural selection is described?
Answer & why
Answer: heritable variation
The population contains inherited differences before the selective event.
All questions
All 6 authored questions for this skill.
Question 1
After many generations, inherited deep-root variants are more common. What is described?
- population change across generations
- heritable variation
- an unsupported individual-choice explanation
- differential reproductive success
A hint
Start with variation already present among individuals, including heritable differences.
Answer & why
Answer: population change across generations
Trait frequencies have changed in the population over generations.
Question 2
A claim says each plant decided to grow an inherited deep-root gene because it needed water. What kind of explanation is this?
- differential reproductive success
- heritable variation
- population change across generations
- an unsupported individual-choice explanation
A hint
Start with variation already present among individuals, including heritable differences.
Answer & why
Answer: an unsupported individual-choice explanation
Need or choice does not create the specified inherited gene in each individual.
Question 3
An insect population has two inherited shell colors before predators arrive. Which ingredient is already present?
- population change across generations
- differential reproductive success
- heritable variation
- an unsupported individual-choice explanation
A hint
Start with variation already present among individuals, including heritable differences.
Answer & why
Answer: heritable variation
Inherited color differences provide variation on which selection may act.
Question 4
Better-camouflaged insects leave more offspring than other insects in the stated environment. Which ingredient is described?
- differential reproductive success
- an unsupported individual-choice explanation
- heritable variation
- population change across generations
A hint
Start with variation already present among individuals, including heritable differences.
Answer & why
Answer: differential reproductive success
The observation concerns unequal contributions to the next generation.
Question 5
Before a drought, a plant population already has inherited differences in root depth. Which part of natural selection is described?
- differential reproductive success
- an unsupported individual-choice explanation
- heritable variation
- population change across generations
A hint
Start with variation already present among individuals, including heritable differences.
Answer & why
Answer: heritable variation
The population contains inherited differences before the selective event.
Question 6
During a drought, deeper-rooted plants produce more surviving offspring on average. Which part of the process is described?
- heritable variation
- an unsupported individual-choice explanation
- population change across generations
- differential reproductive success
A hint
Start with variation already present among individuals, including heritable differences.
Answer & why
Answer: differential reproductive success
The described groups contribute different numbers of surviving offspring.
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