Long answer·Hard exam skill (4/5)·No calculator
Difficulty guide
The label describes the problem, not your ability.
1/5 - Foundational
Warm-up setup; checks one basic idea.
2/5 - Routine exam skill
Normal syllabus skill; usually one main rule or interpretation.
3/5 - Standard multi-step
Exam-style problem with multiple steps or a common trap.
4/5 - Hard exam skill
High-end exam problem; combines methods carefully.
5/5 - Challenge
Stretch problem beyond normal exam pressure.
Question
Use the branching diagram and the idea of evolution by stages to explain why evolution is not a straight ladder of progress.
Total: 5 marks
(a) Identify the common-ancestor idea shown by the diagram. (1 mark)
(b) Explain why endpoints are not necessarily ancestors of one another. (2 marks)
(c) Explain why complex structures can evolve through useful intermediate stages. (1 mark)
(d) State why words like 'higher' and 'lower' can be misleading in evolution. (1 mark)
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