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AQA GCSE · Question 07.4 · Inheritance Variation and Evolution
A scientist made the hypothesis: 'Organism B may have evolved from organism A.'
A scientist studies two fossils, Fossil A and Fossil B. Fossil A is found in a rock layer 50 metres deep. Fossil B is found in a rock layer 20 metres deep. Both fossils have similar body structures, but Fossil B has a more complex skeleton.
What two pieces of evidence support the scientist's hypothesis?
A scientist made the hypothesis: 'Organism B may have evolved from organism A.'
A scientist studies two fossils, Fossil A and Fossil B. Fossil A is found in a rock layer 50 metres deep. Fossil B is found in a rock layer 20 metres deep. Both fossils have similar body structures, but Fossil B has a more complex skeleton.
What two pieces of evidence support the scientist's hypothesis?
How to approach this question
To support the hypothesis that B evolved from A, you need two key types of evidence from the fossil record:
1. Evidence of time: A must have lived before B. How does the depth of rock layers relate to age?
2. Evidence of change: There should be changes between the older and younger fossils that show development.
Evaluate the options based on these two points.
Full Answer
["Fossil A is older than Fossil B.", "Fossil B shows more complex features than Fossil A."]
The fossil record provides strong evidence for evolution.
1. **Age of Fossils:** The principle of superposition states that in layers of sedimentary rock, the oldest layers are at the bottom and the youngest are at the top. Since Fossil A was found deeper (50m) than Fossil B (20m), Fossil A is older. This is consistent with it being an ancestor.
2. **Changes over Time:** Evolution by natural selection leads to gradual changes in species over millions of years. Often, this results in organisms becoming more complex or better adapted to their environment. The fact that the younger fossil (B) is more complex than the older, similar fossil (A) supports the hypothesis that B evolved from A.
Common mistakes
✗ Confusing the relationship between rock depth and age. Deeper is older.
✗ Thinking that any difference (like size) is evidence of evolution. The key is a pattern of change over time, such as increasing complexity.
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