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IB Biology SL D1.3 Mutation and Gene Editing Questions

Practise IB Biology SL D1.3 by classifying mutations, predicting molecular consequences and linking germ-line changes to inheritance.

Syllabus
First assessment 2025
Course
Biology SL
Level
SL

Exam points

  • define a gene mutation and distinguish substitution, insertion and deletion from DNA sequence evidence
  • trace a base substitution through a codon to silent, altered or sickle-cell protein outcomes
  • identify UV, radiation and chemical mutagens and explain how they raise mutation rates
  • explain random mutation as a source of new alleles and genetic variation
  • distinguish germ-line from somatic changes and identify which can be inherited

Covered syllabus points

D1.3.1—Gene mutationsD1.3.2—Base substitution consequencesD1.3.3—Insertion and deletion consequencesD1.3.4—Causes of mutationD1.3.5—Randomness in mutationD1.3.6—Consequences in germ vs. somatic cellsD1.3.7—Mutation as source of variation

Question 1

[Maximum number: 2]

Psammonobiotus balticus belongs to a group of protists (unicellular eukaryotic organisms) that have a shell surrounding most of the cell, which provides shelter from predators. The graph shows the frequency of varying shell lengths in a population of P. balticus.

Figure for Question 1 — IB Biology SL

Mutations may increase variation within a species. Compare and contrast substitution and insertion mutations.

Question 2

[Maximum number: 2]

Thrombophilia is a human genetic condition where the blood has an increased tendency to clot. The condition is caused by a single base substitution mutation in DNA. If a person is homozygous for the gene, they are at greater risk for developing a blood clot than an individual who is heterozygous. The pedigree chart shows the inheritance of thrombophilia in a family.

Figure for Question 2 — IB Biology SL

Explain how a single base substitution mutation in DNA can cause a change to a protein.

Question 3

[Maximum number: 1]

The Cancer Council of New South Wales has stated that one in five cancer deaths are caused by smoking. How can smoking cause cancer?

A

20 % of smokers get cancer.

B

Cigarette smoke contains mutagenic chemicals.

C

Smoking reduces the rate of mitosis in cells.

D

Smoking is addictive.

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