2.7 Aerobic respiration
Summary: Glucose is a type of sugar. It provides all the energy that cells need. Plants produce glucose by photosynthesis. Humans get glucose from carbohydrate foods like rice, bread, and pasta. Tags: science oxford-science student-book-7 biology Created: 2026-05-19 Last Updated: 2026-05-19
After this topic, you will be able to:
- describe the process of aerobic Respiration
- give the word equation for aerobic respiration
- describe how the Reactants and Products of respiration move to and from Cells.
Think back
- Where in a cell does respiration take place?
- Name the structure in the lungs where gas exchange takes place.
- What is the function of red blood cells?
Key idea In aerobic respiration, glucose reacts with oxygen in a chemical reaction. This transfers Energy in food to cells in the body. The reaction takes place in mitochondria.
Key words glucose, aerobic respiration, mitochondria, plasma, haemoglobin
Glucose is a type of sugar. It provides all the energy that cells need. Plants produce glucose by Photosynthesis. Humans get glucose from carbohydrate foods like rice, bread, and pasta.
How do cells transfer energy?
Your body needs energy for everything it does. You need energy to move, to grow, and to keep warm. Energy is required all the time (even when you are asleep!) to keep your body working.
You get your energy from organic Molecules in the food you eat.
To transfer the energy stored in food, glucose reacts with oxygen in a chemical reaction called aerobic respiration. This reaction transfers energy to your cells. The waste products carbon dioxide and water are also formed.
A Name the two substances needed for aerobic respiration.
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B Name the gas produced by aerobic respiration.
Where does respiration happen?
Respiration happens inside tiny structures inside your cells called mitochondria. Figure 1 shows a mitochondrion (singular). All cells contain mitochondria. However, different cells contain different amounts. Muscle cells carry out lots of respiration, so they contain lots of mitochondria.
Figure 1A mitochondrion.
How do glucose and oxygen get into cells?
Glucose and oxygen are carried in the blood.
- During digestion, carbohydrates are broken down, releasing glucose molecules. The molecules are absorbed into the blood through the wall of the small intestine.
- Glucose dissolves in the liquid part of your blood called plasma. It then diffuses into the cells that need it for respiration.
- When you breathe in, oxygen fills the alveoli in your lungs. The oxygen then diffuses into your blood.
- Oxygen joins to haemoglobin (a red protein) in your red blood cells. When it reaches a cell that needs oxygen, the oxygen diffuses into the cell.
Figure 2Glucose and oxygen travel to the cells in the blood.
C State the process by which oxygen and glucose enter body cells.
How does carbon dioxide leave the body?
If carbon dioxide remained in your body, it would build up to a dangerous level. You remove carbon dioxide when you exhale (breathe out).
Carbon dioxide produced during respiration diffuses out of your cells and into the blood plasma. The blood carries it to the lungs, where it diffuses into the alveoli, and is then exhaled.
D Name two substances that are carried through the body in blood plasma.
Literacy skills Read through the information about respiration on these pages for three minutes. Then close your book. Write a definition of aerobic respiration. Swap your ideas with a partner. Can you work together to improve your definition?
Stretch zone
- Copy and complete the sentences. Energy stored in food/water is released inside your cells by the process of photosynthesis/respiration. Carbon dioxide/Glucose and oxygen react together to release carbon dioxide/energy. Carbon dioxide and nitrogen/water are produced as waste products.
- Describe where and how respiration takes place.
Stretch zone
- Explain how oxygen and glucose move to cells for respiration.