Exam skills
What the paper asks you to do
- Predict mass or length changes in osmosis experiments
- Distinguish observation from mechanism
- Explain adaptations for rapid exchange
Foundations
Movement into and out of cells
Explain diffusion, osmosis and active transport through gradients, membranes, energy use and surface-area relationships.5090 syllabus routeConcept · skill · exam language
What to know
Build the topic around four anchors.
- 01Diffusion and net movement
- 02Osmosis through partially permeable membranes
- 03Active transport
- 04Effects of surface area, distance and gradients
Common mistakes
Where marks disappear
- Saying particles move only in one direction
- Describing solute movement as osmosis
- Forgetting that active transport requires energy
Structured practice
Answer these without looking back.
For each prompt, write the biological chain clearly enough that every mark-worthy link is visible.
- 01Predict the effect of concentrated solution on plant tissue.
- 02Explain why villi support rapid absorption.
- 03Compare diffusion with active transport.
Continue learning
Read the connected explanation.
A syllabus-focused guide to gradients, water movement and energy-dependent transport—with the comparisons exam answers need.
This independent teaching resource follows the Cambridge O Level Biology 5090 syllabus direction and is not endorsed by Cambridge International Education.