What mistakes do students make with Evidence for evolution?

Thinking that bacteria deliberately become resistant in response to an antibiotic. That random mutation occurs first and the antibiotic then selects resistant bacteria. Believing that individual bacteria change during their lifetime. That the population changes because resistant individuals survive and reproduce. Assuming fossils only show complete bodies. That fossils include bones, shells, impressions and traces, and often only parts are preserved.

What are the exam tips for Evidence for evolution in Biology AQA GCSE?

Use the word ‘selection’ when explaining antibiotic resistance: state that the antibiotic selects resistant bacteria rather than causing resistance. When describing fossils, refer to changes over time and give a clear example, such as a fossil showing a feature absent in living relatives. Link each piece of evidence back to evolution explicitly, for example by stating that the evidence shows populations changing over many generations.

AQA · GCSE · Biology

Course version: 8461 · Version from Sept 2018

Students should be able to describe the evidence for evolution including…

Full specification wording

Evidence for evolution: Students should be able to describe the evidence for evolution including fossils and antibiotic resistance in bacteria.

Evolution is supported by multiple independent lines of evidence.

Checked against the AQA 8461 specification (opens in a new tab) on 21 September 2026.

Point 1 of 4

Study notes

From the checked teaching notes for this specification point.

The idea

What earns the marks

Fossils are preserved remains or traces of organisms from the past, often found in sedimentary rock, and can show structures not seen in living species.
The fossil record shows that organisms have changed over time, with simpler forms generally found in older rocks and more complex or different forms in newer rocks.
Antibiotic resistance arises from random mutations in bacterial DNA that give some bacteria an advantage when an antibiotic is present.
When an antibiotic is used, susceptible bacteria are killed while resistant bacteria survive and reproduce, increasing the proportion of resistant bacteria in the population.

Common mistakes and how to put them right

Thinking that bacteria deliberately become resistant in response to an antibiotic.
Put it right: That random mutation occurs first and the antibiotic then selects resistant bacteria.
Believing that individual bacteria change during their lifetime.
Put it right: That the population changes because resistant individuals survive and reproduce.
Assuming fossils only show complete bodies.
Put it right: That fossils include bones, shells, impressions and traces, and often only parts are preserved.

Exam tips

Use the word ‘selection’ when explaining antibiotic resistance: state that the antibiotic selects resistant bacteria rather than causing resistance.
When describing fossils, refer to changes over time and give a clear example, such as a fossil showing a feature absent in living relatives.
Link each piece of evidence back to evolution explicitly, for example by stating that the evidence shows populations changing over many generations.

Try the lesson

The start of the Evidence for evolution: Students should be able to describe the evidence for evolution including fossils and antibiotic resistance in bacteria. lesson, made from checked teaching notes for this specification point.

Have a go first

Which type of evidence comes from the preserved remains of organisms that lived many thousands of years ago?

Tip: press 1 to 4 to choose

Listen

Evolution is supported by multiple independent lines of evidence. Fossils show organisms from the past, often unlike living species, and their positions in rock layers reveal change over time. Antibiotic resistance in bacteria provides observable evidence: when bacteria reproduce rapidly, random mutations can make some individuals resistant. In the presence of an antibiotic, susceptible bacteria die while resistant bacteria survive and reproduce, so the proportion of resistant bacteria increases. This is natural selection in action. A strong answer earns marks for these points. Fossils are preserved remains or traces of organisms from the past, often found in sedimentary rock, and can show structures not seen in living species. The fossil record shows that organisms have changed over time, with simpler forms generally found in older rocks and more complex or different forms in newer rocks. Antibiotic resistance arises from random mutations in bacterial DNA that give some bacteria an advantage when an antibiotic is present. When an antibiotic is used, susceptible bacteria are killed while resistant bacteria survive and reproduce, increasing the proportion of resistant bacteria in the population. A common slip: Thinking that bacteria deliberately become resistant in response to an antibiotic. Instead, that random mutation occurs first and the antibiotic then selects resistant bacteria. Exam tip: Use the word ‘selection’ when explaining antibiotic resistance: state that the antibiotic selects resistant bacteria rather than causing resistance.

See it

A top-to-bottom flowchart. The first box says bacteria reproduce rapidly and points to a box saying random mutations in bacterial DNA. That points to a box saying some bacteria are resistant, which points to a box saying antibiotic present. From that box two arrows lead out: one to a box saying susceptible bacteria die, and one to a box saying resistant bacteria survive and reproduce. Both of these boxes point to a box saying the proportion of resistant bacteria increases, which points to a final box saying natural selection in action. — It shows how random mutation followed by antibiotic selection increases the proportion of resistant bacteria.

Label the diagram

Some boxes have lost their names. Pick the right name for each number.

The diagram again, with 3 boxes numbered instead of named. A top-to-bottom flowchart. The first box says bacteria reproduce rapidly and points to a box saying random mutations in bacterial DNA. That points to a box saying some bacteria are resistant, which points to a box saying antibiotic present. From that box two arrows lead out: one to a box saying susceptible bacteria die, and one to a box saying resistant bacteria survive and reproduce. Both of these boxes point to a box saying the proportion of resistant bacteria increases, which points to a final box saying natural selection in action.

1Box 1
2Box 2
3Box 3

0 of 3 labelled

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