Which fossil is dated at about 3.2 million years old?
- Ardi
- Lucy
- The fossils found by Richard Leakey
- None of these
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Answer: B B (1)
Ardi is 4.4 million years old and the fossils found by Richard Leakey are 1.6 million years old. Calculate the difference in age. Give your answer in standard form.
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- 4.4 − 1.6 = 2.8 million years (1)
- 2.8 × 10⁶ years (1)
- allow 1 mark for 2 800 000 or 2.8 million
Fossils provide evidence for human evolution. Explain why scientists sometimes disagree about what fossils show.
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- few fossils are found / most organisms decay before they can become fossils (1)
- fossils are often incomplete / only fragments are found (1)
- so there are gaps in the evidence / it is hard to know how they are related (1)
- new discoveries can change ideas (1)
- Max 3
Describe how stone tools provide evidence for human evolution.
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- older tools are simple, newer tools are more complex / better made (1)
- suggests early humans developed greater skill / intelligence over time (1)
A stone tool is found in a layer of rock. Explain how scientists can find out its age from its environment.
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- the age of the rock layer / materials in the layer (for example volcanic ash) can be found (1)
- the tool is the same age as the layer it was found in (1)
- allow deeper layers are older, so the depth of the layer gives its relative age (1)
- Max 2
The arm of a human, the wing of a bat and the flipper of a whale all have the same basic arrangement of bones, but are used for different jobs. Explain what this suggests about the evolution of these animals.
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- same basic bone structure / pentadactyl limb (1)
- suggests they have a common ancestor (1)
- limbs have become adapted for different functions by natural selection (1)
Describe how genetic analysis has led to the suggestion of three domains rather than five kingdoms.
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- five kingdoms was based on structure / observed features (1)
- genetic analysis showed the prokaryotes are not one closely related group (1)
- Archaea and Bacteria are genetically very different, so three domains: Archaea, Bacteria and Eukarya (1) allow Eukaryota / eukaryotes