This question is about the history of evolutionary theory and the development of life on Earth.
What is meant by the biological term evolution?
Describe the work of Alfred Russel Wallace which led him to independently develop a theory of evolution by natural selection.
For the first two billion years of life on Earth, the atmosphere contained extremely low levels of oxygen, and organisms relied entirely on anaerobic respiration:
glucose⟶ethanol+carbon dioxide \text{glucose} \longrightarrow \text{ethanol} + \text{carbon dioxide} glucose⟶ethanol+carbon dioxideFollowing the Great Oxidation Event, atmospheric oxygen increased, allowing some organisms to evolve aerobic respiration:
glucose+oxygen⟶carbon dioxide+water \text{glucose} + \text{oxygen} \longrightarrow \text{carbon dioxide} + \text{water} glucose+oxygen⟶carbon dioxide+waterExplain why the transition from anaerobic respiration to aerobic respiration allowed larger, multicellular primary consumers to evolve and how this enabled the existence of secondary consumers.
Scientists observe that when a new predator is introduced to an isolated ecosystem, the prey population (primary consumers) often begins to evolve much faster.
Explain why this statement is true.
38 exam-style questions on OCR GCSE Biology 5.2 Natural selection and evolution, covering 5.2.1 Genetic variation within a population, 5.2.2 Developments in classification systems, 5.2.3 How evolution occurs through natural selection, 5.2.4 Evolution as change over time, 5.2.5 Evidence for evolution, and 5.2.6 Darwin and Wallace. Each one has a worked solution and a mark scheme showing where the marks go.