A-LevelBiologySelection and evolutionOct/Nov 2021Paper 4 Q85 Marks
California salamanders are terrestrial amphibians. An original population of California salamanders occupied an area of forest in northern California. Approximately 10 million years ago, two separate populations, A and B, started to migrate from the original population. • Population A travelled along the coast of California, to the west of the Great Central Valley. • Population B travelled east of the Great Central Valley. The two populations now live close to each other in southern California. Fig. 8.1 outlines the migratory routes of populations A and B. [Figure 8.1] Salamanders from population A rarely interbreed with salamanders of population B. If they do interbreed, the offspring are infertile.
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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