1.2 Metabolism: What keeps cells alive?
Use enzyme models and rate evidence to explain respiration and photosynthesis in living cells.
How to study WJEC GCSE The Sciences
Move from a scientific model to a prediction or method, collect or interpret evidence, show quantitative working and finish with a conclusion whose limits match the data.
Core concepts
Concept 1
Explain enzyme specificity and the effects of temperature and pH.
Exam cue: Identify the unit, entered tier, supplied reference material, command word and relevant scientific enquiry skill.
Concept 2
Compare aerobic and anaerobic respiration and their energy yields and products.
Exam cue: Link a change in rate to collision, active-site shape or the limiting resource rather than simply describing the graph.
Concept 3
Investigate photosynthesis and interpret limiting-factor data.
Exam cue: Use scientific terminology, show quantitative working with units, and connect conclusions to data and the stated model.
Concept 4
Official subtopics: 1.2.1 Function of enzymes; 1.2.2 Aerobic and anaerobic respiration in humans; 1.2.3 Photosynthesis and factors that affect it.
Concept 5
Scientific enquiry and mathematical skills apply in this topic; bold amplification is Higher Tier only.
Risk pitfalls and guardrails
Saying enzymes die or that plants only respire at night.
Guardrail: Do not import outgoing 3430QD content, another science route, a fixed required-practical list or unsupported tier and connection assumptions.
Recalling a fact without applying it to the observation, data, practical method or unfamiliar context.
Guardrail: Use the live secure pack: Task A may use groups of up to three; Task B is individual and highly controlled. Two enquiries are selected by the centre from three.
Importing content, required practicals, tier rules or paper structure from the outgoing WJEC or another awarding-body route.
Guardrail: Bold amplification is Higher-only. Units 1-6 may mix tiers, but Unit 7 is untiered.
Memory anchors
Enzyme
A protein that acts as a biological catalyst.
Active site
The region of an enzyme whose shape is complementary to its substrate.
Aerobic respiration
Energy transfer using glucose and oxygen, producing carbon dioxide and water.
Anaerobic respiration
Energy transfer without oxygen, producing less usable energy.
Limiting factor
The factor in shortest supply that restricts the rate of a process.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
Why does an enzyme usually catalyse only one reaction or a small group of related reactions? Use the enzyme, respiration or photosynthesis evidence stated in the question. Test the proposed explanation against every stated fact.
An enzyme works faster as temperature rises from 10 °C to 37 °C. What best explains the increase? Use the enzyme, respiration or photosynthesis evidence stated in the question. Select the claim supported by the observation.
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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