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.
Early Earth's atmosphere contained extremely low levels of oxygen, and many early organisms used anaerobic pathways to release energy. One example of an anaerobic pathway is:
glucose⟶ethanol+carbon dioxide \text{glucose} \longrightarrow \text{ethanol} + \text{carbon dioxide} glucose⟶ethanol+carbon dioxideAs oxygen availability increased, aerobic respiration became possible in more environments:
glucose+oxygen⟶carbon dioxide+water \text{glucose} + \text{oxygen} \longrightarrow \text{carbon dioxide} + \text{water} glucose+oxygen⟶carbon dioxide+waterExplain how increasing oxygen availability and aerobic respiration could support larger, more active multicellular primary and secondary consumers and more complex food webs.
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.
122 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.