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Ecological Niches · Paper 1 — Free Biology HL Practice Questions

What this topic covers

This theme is built on one repeated argument: structure exists because it does a job, and you can predict the job from the structure. Examiners test this exact logic at every scale — a motor protein's shape tells you which way it walks a microtubule, a red blood cell's missing nucleus tells you why it can pack more haemoglobin, a gill's countercurrent geometry tells you why it out-performs a lung-style parallel flow. Several chunks here — muscle and motility, enzyme kinetics, endosymbiotic theory, detailed phloem loading — exist only on the HL paper, and they're flagged below. Get the mechanism words right (troponin, not tropomyosin; ATP-binding, not hydrolysis) because that's where the marks actually sit.

Read the full Form and Function lesson notes →

1FoundationMCQEcological niche concept1 markPaper 1~2 min

In a rocky shore ecosystem, Chthamalus and Balanus barnacles coexist. Chthamalus naturally occupies only the upper shore, but when Balanus is experimentally removed from the lower shore, Chthamalus colonises that zone as well. Balanus cannot survive in the upper shore regardless of competition. Which conclusion is best supported by this experiment?

Solutions

2FoundationMCQEcological niche concept1 markPaper 1~2 min

Two species of warblers coexist in the same forest and consume similar insect prey. Species A forages exclusively in the upper canopy, while Species B forages exclusively in the lower understory. Which term most precisely describes the mechanism that allows these two species to coexist?

Solutions

3MasteryMCQEcological niche concept1 markPaper 1~2 min

In a temperate grassland, three grasshopper species occupy distinct ecological niches. Species X feeds exclusively on grasses across all temperatures. Species Y feeds exclusively on forbs across all temperatures. Species Z feeds on both grasses and forbs, but only when air temperature exceeds 25°C. Which statement correctly describes the fundamental niche breadth of these three species?

Solutions

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