GCSE Combined Science revision · Biology: homeostasis, inheritance and ecology

Evidence for evolution

The idea

Evidence for evolution includes fossils and antibiotic-resistant bacteria. Fossils form when parts of organisms do not decay, when parts are replaced by minerals, or from preserved traces such as footprints. The fossil record is incomplete because early soft-bodied organisms rarely fossilised and many fossils were destroyed. Extinction can be caused by new predators, new diseases, more successful competitors, or environmental change.

Name a type of evidence.
Explain what it shows.
Explain its limits.

Watch out MRSA shows evolution happening now: resistant strains spread when antibiotics are overused.

See it worked

Worked example

Give two ways the spread of antibiotic-resistant bacteria can be reduced.

Doctors should not prescribe antibiotics for viral or minor infections.
Patients should complete the full course.

Answer Only prescribe when needed, and complete the course

Your turn

Question 1Calculator allowed1 mark

Why is the fossil record incomplete?

Question 2Calculator allowed1 mark

Which is a cause of extinction?

Question 3Calculator allowed3 marks

Explain how fossils provide evidence for evolution.

Write your answer, then see a model answer

Change over time.
Rock layers and dating.

Answer Fossils from different rock layers show how organisms changed gradually over long periods, from simple life forms to more complex ones.

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