IB Biology HL 1.1.9 DNA proofreading Question Bank

Practise IB Biology HL 1.1.9 by applying dna proofreading concepts to exam-style questions.

Exam points

identify the relevant biological structure, process or evidence
apply the correct biological mechanism to the question
evaluate the result using data, adaptation or ecological reasoning

[Maximum number: 4]

Living organisms have mechanisms for preventing or reducing change.

Explain how mutation is avoided during DNA replication.

a. complementary base pairing (between DNA nucleotides);

b. adenine pairs with thymine and cytosine pairs with guanine;

c. new strands with same/correct sequence/copy produced by semiconservative replication OR

semiconservative replication is using a template strand (to make a new strand);

d. DNA polymerase (III) adds nucleotides to the growing chain/to the template strand;

e. proofreading is correction of errors/mutations (during DNA replication)

f. proofreading by DNA polymerase III

OR

error in replication/nucleotide with mismatched base detected by DNA polymerase III

g. DNA polymerase III has $3^{\prime}$ to $5^{\prime}$ exonuclease activity

OR

DNA polymerase III reverses and excises nucleotide

OR

(mismatched) nucleotide removed and replaced (by DNA polymerase III);

4

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D1.1.9 (HL)—DNA proofreading question 1