D1.3 Mutations and gene editing questions for IB Biology
42 questions on Mutations and gene editing, written by Augment in the style of IB exam papers. Six of them are below in full, to answer on paper.
- IB Biology
- Part of D Continuity and change
- SL and HL
Questions by paper and level
SL and HL questions are for students at either level. HL only questions cover what only HL students study.
| Paper | SL and HL | HL only | All |
|---|---|---|---|
| Paper 1A | 14 | 6 | 20 |
| Paper 1B | 3 | 2 | 5 |
| Paper 2 | 9 | 8 | 17 |
| Every paper | 26 | 16 | 42 |
Counted on
Questions to try
Written by Augment in the style of IB exams, not past papers. Answer them on paper, then check each one against its markscheme with a free account.
Part of the coding strand of a gene has the base sequence ATGCCAGTTAAC. Which sequence is the result of a single base substitution?
The bacterium Serratia marcescens forms red colonies on agar when grown at 25 °C because it produces a red pigment. Students spread 0.1 cm3 of the same diluted culture onto each of 15 agar plates. With the lids removed, groups of three plates were exposed to an ultraviolet (UV) lamp at a distance of 30 cm for different times. All plates were then incubated at 25 °C for 48 hours. The students counted the total number of colonies and the number of white (unpigmented) colonies on each plate. The table shows the means for each exposure time.
UV exposure time / s | Mean total colonies | Mean white colonies | White colonies / % of total |
|---|---|---|---|
0 | 312 | 1 | 0.3 |
15 | 228 | 3 | 1.3 |
30 | 141 | 5 | |
45 | 76 | 4 | 5.3 |
60 | 34 | 3 | 8.8 |
- (a)
State the independent variable in this investigation.
1 mark
- (b)
Calculate the percentage of colonies that were white after 30 s of exposure.
1 mark
- (c)
Describe the effect of the length of UV exposure on the total number of colonies and on the percentage of white colonies.
2 marks
- (d)
Suggest why the percentage of white colonies, rather than the number of white colonies, was used to compare the exposure times.
1 mark
- (e)
Explain how exposure to UV could produce white colonies.
2 marks
- (f)
Suggest one reason why the conclusions about white colonies are less reliable than those about total colonies.
1 mark
Genetic information varies between individuals and between species.
- (a)
Outline what single-nucleotide polymorphisms (SNPs) are and how they arise.
4 marks
- (b)
Describe how the polymerase chain reaction (PCR) and gel electrophoresis can be used to amplify and separate DNA.
4 marks
- (c)
Explain the current and potential future uses of whole genome sequencing, and why these uses are becoming more widespread.
7 marks
A single-nucleotide polymorphism (SNP) in a gene changes the triplet CCA on the coding strand to CCG. People with either version of the gene produce identical polypeptides. What is the reason for this?
A strain of the bacterium Salmonella enterica cannot make the amino acid histidine because of a mutation in a gene for histidine synthesis. It cannot grow on a medium without histidine unless a new mutation restores the function of this gene. Colonies that grow on this medium are called revertants.
Researchers tested whether chemical Z is a mutagen. Equal numbers of bacteria were spread on five plates of histidine-free medium for each treatment. Chemical Z, dissolved in a solvent, was added to each plate; control plates received the solvent only. The plates were incubated for 48 hours and revertant colonies were counted.
Chemical Z per plate / µg | Mean number of revertant colonies | Standard deviation |
|---|---|---|
0 (solvent only) | 24 | 5 |
10 | 27 | 6 |
50 | 48 | 7 |
100 | 95 | 11 |
500 | 61 | 9 |
- (a)
Calculate the percentage increase in the mean number of revertant colonies when 100 µg of chemical Z was added, compared with the solvent-only control.
1 mark
- (b)
Using the standard deviations, evaluate whether 10 µg and 50 µg of chemical Z had an effect on the number of revertants.
2 marks
- (c)
Explain why revertant colonies grew on the plates that received solvent only.
2 marks
- (d)
Suggest a reason for the lower number of revertants at 500 µg than at 100 µg.
2 marks
- (e)
Outline the reason for using five plates for each treatment.
1 mark
- (f)
Explain why a chemical that causes mutations in this test may increase the risk of cancer in humans.
2 marks
Changes over time leave a record in the base sequences of DNA and RNA.
- (a)
Outline how gene mutations arise and how they change base sequences.
4 marks
- (b)
Explain how the molecular clock is used to estimate when clades diverged, and why it can only give estimates.
7 marks
- (c)
Describe the evidence for the classification of all organisms into three domains.
4 marks
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More questions in Continuity and change
- D1.1DNA replication
- D1.2Protein synthesis
- D1.3Mutations and gene editingThis page
- D2.1Cell and nuclear division
- D2.2Gene expressionHL only
- D2.3Water potential
- D3.1Reproduction
- D3.2Inheritance
- D3.3Homeostasis
- D4.1Natural selection
- D4.2Stability and change
- D4.3Climate change
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