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Living things get energy from food. Does it make a difference whether they have oxygen?
Cellular Respiration lab · Last updated: 16 October 2026
Living things get energy from food, but does oxygen make a difference? In this 3D lab, you compare respiration with oxygen and without it, and see what each produces. It explains why we breathe, why muscles ache after a sprint and how yeast makes bread rise.
What you'll discover
- Cells break down glucose to release energy, and with oxygen they release far more of it.
- Without oxygen, muscles make lactic acid and yeast makes alcohol and carbon dioxide.
- Aerobic respiration produces carbon dioxide and water, the same carbon dioxide you breathe out.
The science in plain words
Respiration is the chemical process every living cell uses to release energy from food. It is not the same as breathing, although breathing supplies the oxygen and removes the waste gas. Most of the energy comes from glucose, a sugar made by digesting food.
With plenty of oxygen, cells carry out aerobic respiration, mostly inside tiny structures called mitochondria. Glucose and oxygen react to make carbon dioxide and water, and the energy released is stored in a molecule called ATP that powers everything from muscle movement to thinking. Aerobic respiration breaks glucose down completely, so it releases a large amount of energy from each molecule.
When oxygen is scarce, cells can switch to anaerobic respiration, which breaks glucose down only partly and releases much less energy. In hard-working human muscles this makes lactic acid, which can cause cramps and the burning feeling during a sprint. Yeast and some bacteria do something similar but make alcohol and carbon dioxide instead, which is how bread rises and how fermentation works. Because aerobic respiration yields so much more energy, large active animals depend on a steady supply of oxygen.
Where it fits
Common questions
Is respiration the same as breathing?
No. Breathing is moving air in and out of the lungs. Respiration is the chemical reaction inside cells that releases energy from food. Breathing supports respiration by bringing in oxygen and carrying away the carbon dioxide that respiration produces.
Why do my muscles hurt after running fast?
During a sprint your muscles need energy faster than oxygen can arrive, so they also use anaerobic respiration. This makes lactic acid and leaves the muscles tired and burning. The aching a day or two later is mostly from small strains in the muscle fibres as they adapt.
What is the difference between aerobic and anaerobic respiration?
Aerobic respiration uses oxygen and breaks glucose down completely into carbon dioxide and water, releasing a lot of energy. Anaerobic respiration happens without oxygen, releases much less energy and makes lactic acid in muscles or alcohol and carbon dioxide in yeast.
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- Carbon Cycle: When we burn fuel, where does the carbon go? And how much of it stays in the air?
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Try it yourself
The Cellular Respiration lab is one of the interactive 3D science labs inside Taz. Change one thing, predict what will happen, then run it and watch. Labs open after you sign in.