Educational worksheet on gene mutations with DNA sequence analysis and multiple-choice questions.

Final Answer:
1. Deletion
2. Substitution
3. Insertion

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Explanation:
Let’s go step by step for each question:

Question 1:
Original DNA: A A A T C C G G G
Mutated DNA: A A A _ C C G G G
We see one letter (T) is missing in the mutated version — it’s gone. When a base is *removed*, that’s called a deletion.

Question 2:
Original DNA: A A A T C C G G G
Mutated DNA: A A A C C C G G G
Compare position 4: original has T, mutated has C. Only one base changed — not added, not removed, just swapped. That’s a substitution.

Question 3:
Original DNA: A A A T C C G G G
Mutated DNA: A A A T A C C G G G
Look carefully: after the first “A A A T”, there’s an extra A before the rest. The sequence got longer by one base. When a new base is *added*, it’s an insertion.

So the answers are:
1. Deletion
2. Substitution
3. Insertion