Transport Summary | IGCSE Biology Revision

Complete Transport Summary for IGCSE Biology

Biology editorial review is supported by the named review panel. Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.

Key point

Transport spans Topics 3, 8, and 9. Cell level: diffusion, osmosis, active transport. Plants: xylem (water, passive) and phloem (sugars, active). Humans: heart, blood vessels, blood components. All serve the same purpose: delivering substances and removing waste.

Transport is one of the biggest themes in IGCSE Biology: it spans cell transport (Topic 3), plant transport (Topic 8), and human transport (Topic 9). This guide brings together all transport concepts in one place, showing how they connect.

Cell-level transport (Topic 3)

Three mechanisms move substances in and out of cells:

Diffusion: net movement of particles from high → low concentration (passive, no energy)
Osmosis: net movement of water from dilute → concentrated solution through a partially permeable membrane (passive)
Active transport: movement against the concentration gradient using energy from respiration (active)

Plant transport (Topic 8)

Xylem: water + minerals, upward only, dead cells, passive (transpiration pull).
Phloem: dissolved sugars, both directions (source → sink), living cells, active (translocation).
Root absorption: water by osmosis, minerals by active transport.

Human transport (Topic 9)

The circulatory system:
Heart: double pump: right side pumps to lungs (pulmonary), left side pumps to body (systemic).
Arteries: thick walls, high pressure, carry blood away from heart.
Veins: thin walls, valves, low pressure, carry blood to heart.
Capillaries: one cell thick, exchange of substances.
Blood: plasma (transport medium), red blood cells (O₂), white blood cells (defence), platelets (clotting).

Connecting the themes

All transport ultimately serves the same purpose: delivering substances to cells and removing waste. Diffusion, osmosis, and active transport occur at the cellular level. Xylem and phloem move substances over long distances in plants. The circulatory system moves substances over long distances in animals. The same principles (concentration gradients, surface area, energy) apply throughout.

Frequently asked questions

Are these topics linked in the exam?

Yes: questions often cross topic boundaries. For example, you might be asked to explain how oxygen gets from the air to a muscle cell, which requires knowledge of gas exchange (Topic 11), the heart and blood vessels (Topic 9), and diffusion (Topic 3).