This Grade 12 worksheet helps students understand mutations and genetic variation.
Students will complete fill-in-the-blank questions covering substitution, deletion, insertion, and evolution.
Mutations and Genetic Variation — 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 tell the three kinds of mutation apart by what actually happens to the sequence.
Question 1 — put them in order
Click these in order, from a mutation to its effect on a population.
Base → gene → trait → population. A mutation is a very small change that only matters because of what it scales up into.
Question 2
What is a substitution mutation?
Swapped. The sequence stays the same length — which is why a substitution is often less damaging than a deletion or an insertion.
Question 3
What are mutagens?
They raise the mutation rate. Radiation and certain chemicals are examples — they do not create specific mutations, they make mutations more likely.
Question 4
Which kind of mutation makes the DNA sequence longer?
Insertion adds a base. Deletion removes one, and substitution swaps one — only insertion lengthens the sequence.
Question 5
Why does genetic variation matter for evolution?
Natural selection can only favour one variant over another if variants exist. Mutation is where most of that raw material comes from.
Question 6 — select all that apply
Select every kind of mutation the worksheet names, then press Check.
Substitution, deletion and insertion. Transcription and translation are steps in making a protein, and respiration is how a cell releases energy — none of them are mutations.
Think about it
A substitution keeps the sequence the same length but a deletion does not. Why might that matter?
Most mutations are harmless or harmful. Why do the rare useful ones matter so much?
Mutations happen at random. Does that mean evolution is random?
Which mutations can be passed to offspring, and which cannot?