GCSE Biology: Transport in Cells

Diffusion, osmosis and active transport are the three movement processes every GCSE Biology student must be able to tell apart — and confusing them is one of the most reliable ways to lose marks. This quiz drills the distinctions until they stick.

Diffusion questions cover the definition and the factors that speed it up (temperature and concentration gradient), plus its flagship application: gas exchange in the lungs, with oxygen and carbon dioxide each moving down its own gradient in opposite directions. Osmosis gets the precision treatment the specification demands — it is specifically the movement of water across a partially permeable membrane — including a scenario question about a plant cell placed in a concentrated solution, where water leaves the cell, and a question on what "partially permeable" actually means.

Active transport is tested through its two canonical examples: root hair cells absorbing mineral ions from soil where the concentration is lower than inside the cell, and glucose absorption in the small intestine when the gut concentration falls below blood concentration. Both cases turn on the same logic — movement against a concentration gradient requires energy — and the questions force you to reason about gradient direction, not just recite the definition.

The set closes with surface area to volume ratio: why the ratio falls as organisms get bigger, and the exchange-surface adaptations (large surface area, thin membranes, rich blood supply) that evolution supplies in response — the conceptual thread that connects this topic to lungs, gills, villi and roots across the rest of the course. Every question is scenario-based and self-contained, with explanations that spell out the gradient reasoning.

• Define diffusion and identify the factors that increase its rate
• Define osmosis precisely as water movement across a partially permeable membrane
• Predict water movement when cells are placed in solutions of different concentrations
• Explain why root hair cells and gut glucose absorption require active transport
• Relate surface area to volume ratio to the need for specialised exchange surfaces

Topic scope follows the transport-in-cells section of the Department for Education's GCSE combined science subject content: diffusion, osmosis and active transport, factors affecting rate, and the relationship between surface area to volume ratio and exchange surfaces.