Natural selection
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Question
Define evolution.
Answer
Evolution is the gradual change in inherited traits in populations over generations.
💡 Hint
Inherited traits change over generations.
Question
Why can rapid environmental change cause extinction?
Answer
If change happens faster than populations can adapt through natural selection, survival and reproduction drop and the species may die out.
💡 Hint
Too fast to adapt.
Question
What is natural selection?
Answer
Natural selection is the process where individuals with advantageous traits are more likely to survive and reproduce, making those traits more common over time.
💡 Hint
Traits that help survival spread.
Question
Define speciation.
Answer
Speciation is the formation of a new species when populations become reproductively isolated and diverge genetically over time.
💡 Hint
Isolation → divergence → new species.
Question
List the four steps of natural selection (in order).
Answer
Genetic variation, survival advantage, reproduction, inheritance.
💡 Hint
Variation → survival → reproduction → inheritance.
Question
What does “reproductive isolation” mean?
Answer
Reproductive isolation means two populations can no longer interbreed to produce fertile offspring.
💡 Hint
Can’t successfully breed.
Question
Give a simple sequence for how isolation can lead to speciation.
Answer
A population becomes isolated, experiences different selection pressures, accumulates genetic differences, and eventually becomes reproductively isolated from the original population.
💡 Hint
Separated → different selection → new species.
Question
In natural selection, why is variation essential?
Answer
Because without genetic variation, all individuals respond the same way to a change, so selection cannot favour one trait over another.
💡 Hint
No variation = nothing to select.
Question
How does evolution increase biodiversity?
Answer
Evolution can produce new species over time (speciation), increasing species diversity and contributing to overall biodiversity.
💡 Hint
Evolution → speciation → more species.
Question
Exam link: how can you connect evolution to ecosystem resilience?
Answer
Evolution generates biodiversity (more species and traits), which increases redundancy and makes ecosystems more resilient to disturbance.
💡 Hint
Evolution → biodiversity → resilience.
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Full study notes for Natural selection
Topic 3.2 hub
Natural selection, variation and speciation
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