ATP and Energy in Biological Processes — AQA GCSE Biology
Respiration transfers energy from glucose into a usable form that cells can use for their activities.
Why respiration matters
Respiration is an exothermic reaction that occurs continuously in all living cells. It transfers the energy stored in glucose so the cell can use it. Respiration is sometimes described as supplying energy for all the chemical reactions in cells.
Uses of the energy released
The energy transferred by respiration is used for:
- Movement — muscle contraction.
- Keeping warm — maintaining a constant body temperature in mammals and birds.
- Building larger molecules from smaller ones (e.g. proteins from amino acids, starch and cellulose from glucose) — these synthesis reactions need energy.
- Active transport of substances across membranes.
Energy and metabolism
These energy-requiring processes are part of the body's metabolism — the sum of all the chemical reactions in the body. Without a constant supply of energy from respiration, cells could not carry out these reactions and would die.
Exam tips
- Respiration is exothermic and happens in all living cells, continuously.
- Learn the uses of the energy released (movement, warmth, building molecules, active transport).
- Link energy-requiring synthesis reactions (making proteins, starch, cellulose) to respiration.
- Don't confuse respiration (releases energy in cells) with breathing (gas exchange).