Use the aerobic respiration word equation
Identify reactants and products without losing energy release.
Section B12.1 · Respiration
Exam scope and assessment notes
Mapped to the named 0973 section using teaching from the corresponding single-science course. A 0973-specific review of every Core and Supplement objective is still in progress. Written practice is self-checked; it does not demonstrate supervised laboratory competence or award an official Cambridge grade. This qualification reports two grades on the 9–1 scale; confirm the entry route for your zone and exam series.
Before you begin
- Recall cell processes, enzymes and the distinction between gas exchange and breathing.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which side contains reactants?
What you will learn
- Read both sides of the equation
- Use the equation in explanations
Use the aerobic respiration word equation
| Feature | Meaning |
|---|---|
| Reactants | Glucose + oxygen |
| Reaction | → |
| Products | Carbon dioxide + water |
| Energy | Released; not an atom-containing reagent |
Read both sides of the equation
For the specified glucose model, the word equation is glucose + oxygen → carbon dioxide + water. Glucose and oxygen are reactants, written before the arrow. Carbon dioxide and water are products, written after it. The arrow records the direction of the overall reaction rather than a physical tube carrying glucose straight into a lung.
Energy is released by the process. It is not a material molecule whose atoms need to be added to the products when balancing the chemical equation. You can state energy release alongside the equation, while retaining the four chemical substances in their correct positions. Do not replace water with hydrogen or carbon dioxide with carbon.
Use the equation in explanations
The word equation describes the overall cellular reaction, not every enzyme-catalysed step. Carbon dioxide leaving the body can originate from tissue respiration, while water has many roles and routes in an organism. A question asking for the products needs their names; an unrelated statement about sweating does not replace them.
Use the equation to distinguish aerobic respiration from photosynthesis and from anaerobic reactions. Aerobic respiration uses oxygen and breaks down glucose. Do not reverse the word equation because a plant is involved: photosynthesis is a different process, and a plant cell performing aerobic respiration follows the same specified equation.
Sources for this lesson
Pause and explain
Which is the correct word equation?
Worked example
Name the two reactants and two products in the glucose aerobic model.
Show the worked solution
- Read the left side as inputs.
- Read the right side as products.
Answer Reactants: glucose and oxygen. Products: carbon dioxide and water.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Write the word equation for aerobic respiration using glucose.
Give me a hint
Put nutrient and oxygen before the arrow.
Compare my reasoning
- Reactants are glucose and oxygen.
- Products are carbon dioxide and water.
Glucose + oxygen → carbon dioxide + water.
Look for these in your work
- Give both reactants
- Give both products
A plant cell respires aerobically. A student reverses the equation to show oxygen made. Correct the answer.
Give me a hint
The process, rather than the organism name, determines the equation.
Compare my reasoning
- Aerobic respiration uses oxygen.
- Photosynthesis is a separate reaction.
Use glucose + oxygen → carbon dioxide + water; being a plant does not reverse the aerobic respiration equation.
Look for these in your work
- Retain oxygen use
- Separate photosynthesis
Does energy release mean energy must be treated as a fifth atom-containing substance when balancing?
Give me a hint
Energy release and chemical atom counts have different roles.
Compare my reasoning
- The four substances provide the atom balance.
- Energy release is stated alongside the reaction.
No. Balance glucose, oxygen, carbon dioxide and water; describe energy release without treating energy as an atom-containing molecule.
Look for these in your work
- Separate energy and matter
- Retain energy release
Common mistakes
- Reversing the equation for a plant.
- Adding energy as an atom-containing chemical product.
What can you explain now?
Which is the correct word equation?
Compare with the explanation
Glucose + oxygen → carbon dioxide + water
This is the specified aerobic glucose model.
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Make it stick
Write and label the aerobic word equation.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.