WJEC GCSE Biology: Cells and exchange (Unit 1) overview
An overview of the cells and exchange content in WJEC GCSE Biology Unit 1 (sections 1.1 and 1.3), mapping cell structure and organisation, specialised cells and microscopy, diffusion, osmosis and active transport, the digestive system, digestive enzymes and food tests, and absorption, and how they are examined.
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The first biology module builds from the structure of a single cell up to how the body absorbs digested food. It draws together two sections of WJEC Biology Unit 1: section 1.1 Cells and movement across membranes and section 1.3 Digestion and the digestive system. This page maps the module and links to a focused answer page for each topic.
The cells and exchange content
- Cell structure and organisation
- The sub-cellular structures of animal and plant cells, the differences between them, and the levels of organisation from cells to organ systems. See Cell structure and organisation.
- Specialised cells and microscopy
- Cell differentiation, the adaptations of common specialised cells, and the magnification equation with unit conversion and scale bars. See Specialised cells and microscopy.
- Diffusion, osmosis and active transport
- The three ways substances cross membranes, the factors affecting diffusion, the effect of osmosis on cells, and the osmosis practical. See Diffusion, osmosis and active transport.
- The digestive system
- A balanced diet, the organs of the alimentary canal, mechanical and chemical digestion, and the role of bile. See The digestive system.
- Digestive enzymes and food tests
- Carbohydrases, proteases and lipases and their products, the effect of temperature and pH, and the four food tests. See Digestive enzymes and food tests.
- Absorption of digested food
- How the soluble products of digestion are absorbed in the small intestine and the adaptations of villi. See Absorption of digested food.
How this module is examined
This content is assessed on Unit 1, a written paper of 1 hour 45 minutes, worth 80 marks and 45% of the qualification, tiered at Foundation and Higher. Expect short answer, structured, data response and extended writing questions. The maths here includes magnification, real-size calculations and percentage change in osmosis, all with a calculator.
How to study this module
Cells and exchange rewards precise recall and confident calculation.
- Learn the cell structures and their functions. Be ready to compare animal and plant cells and to put the levels of organisation in order.
- Drill the calculations. Magnification, real size and percentage change in mass all appear; practise the unit conversions.
- Link structure to function. Specialised cells and the villi are classic "feature so function" questions.
- Learn the food tests cold. Reagent, method and positive colour for each of starch, reducing sugar, protein and lipid.
- Master the exchange-surface idea. Large surface area, short diffusion distance and a steep concentration gradient explain the villi, the alveoli and more.
For the official specification
WJEC publishes the full specification, past papers and mark schemes at wjec.co.uk. Always revise from the current specification and WJEC's own past papers.
Sources & how we know this
- WJEC GCSE Biology specification (from 2016) — WJEC (2016)