This Grade 12 worksheet helps students understand evolution and natural selection.
Students will complete fill-in-the-blank questions covering adaptations, variation, survival, and fitness.
Evolution and Natural Selection — Practice
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Try these before or after you print the worksheet. The printable asks you to fill in the words. This asks you to put the steps of natural selection in order and to use fitness the way a biologist does — which is not what the everyday word means.
Question 1 — put them in order
Click the steps of natural selection in order.
Variation → selection → differential reproduction → change. Every step is needed: without variation there is nothing to select, and without reproduction nothing is passed on.
Question 2
In biology, what does fitness mean?
Surviving and reproducing. A small, slow organism that leaves many offspring is fitter, biologically, than a strong one that leaves none.
Question 3
What are adaptations?
Helpful inherited traits. An adaptation is shaped over generations, not acquired by one individual trying.
Question 4
Natural selection acts on variation. Where does variation come from?
Mutation and recombination. The environment does not make traits — it decides which existing ones do well.
Question 5
Which of these does evolution act on?
Populations. An individual cannot evolve; the proportions of traits within a group change over time.
Question 6 — select all that apply
Select every thing natural selection needs in order to work, then press Check.
Variation, heritability and differences in reproduction. If every individual survived and reproduced equally, nothing would be selected at all.
Think about it
A giraffe cannot stretch its neck and pass the longer neck on. So how did long necks become common?
Fitness means reproducing, not being strong. Can you think of an organism that is biologically fit but physically weak?
The environment decides which traits help. What happens when the environment changes?