Biology · Edexcel Paper 2
Respiration
How living cells release energy from glucose by respiration: aerobic respiration in the mitochondria, anaerobic respiration in muscles and in yeast, how the two compare, and the core practical on measuring the rate of respiration with a respirometer. Matches Edexcel 8.9 to 8.11, for Combined Science and separate Biology. Every lesson is for both courses, and there are no Higher tier only or separate only parts.
Lessons
Ticks are remembered on this device only.
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1
Cellular Respiration and Aerobic Respiration
Every living cell, in animals, plants and microorganisms alike, needs a constant supply of energy. This lesson is for both Combined Science and separate…
9 terms -
2
Anaerobic Respiration
Sometimes cells cannot get enough oxygen, or there is no oxygen at all, and they still have to release energy. This lesson is for both Combined Science and…
9 terms -
3
Core Practical: Investigating the Rate of Respiration
Respiration happens inside cells, so you cannot watch it, but you can measure how fast an organism uses oxygen. This lesson is for both Combined Science and…
9 terms -
Knowledge organiser
The whole chapter on a page or two of A4 — to revise from on screen or print.
Key terms in this chapter
All 27, gathered from every lesson.
- Respiration
- A series of chemical reactions in living cells that releases energy from nutrient molecules such as glucose.
- Aerobic respiration
- Respiration that uses oxygen to break glucose down completely into carbon dioxide and water, releasing energy.
- Exothermic reaction
- A reaction that transfers energy to the surroundings, usually as heat.
- Metabolic processes
- The chemical reactions that take place in a living organism, which use the energy released by respiration.
- Mitochondria
- The structures in a cell where most of the reactions of aerobic respiration take place.
- Glucose
- A sugar that is the main fuel for respiration, made in photosynthesis or from digested food.
- Active transport
- The movement of substances against a concentration gradient, using energy from respiration.
- Ventilation
- Breathing: the movement of air into and out of the lungs.
- Red blood cell
- A blood cell packed with haemoglobin that carries oxygen from the lungs to the respiring cells.
- Anaerobic respiration
- The release of energy from glucose without using oxygen, which releases much less energy than aerobic respiration.
- Lactic acid
- The product of anaerobic respiration in muscle cells, which causes muscle fatigue.
- Oxygen debt
- The extra oxygen needed after vigorous exercise to break down the lactic acid that has built up.
- Muscle fatigue
- The tiredness of muscles caused by a build-up of lactic acid, so they stop contracting efficiently.
- Fermentation
- Anaerobic respiration in yeast, which changes glucose into ethanol and carbon dioxide.
- Ethanol
- The alcohol made by yeast during fermentation, found in beer and wine.
- Yeast
- A single-celled fungus that can respire aerobically and anaerobically.
- Heart rate
- The number of times the heart beats in one minute.
- Recovery time
- The time taken for heart rate and breathing rate to return to resting levels after exercise.
- Respirometer
- Apparatus that measures the rate of respiration of organisms by the oxygen they take in.
- Soda lime
- A chemical that absorbs carbon dioxide, so that only the oxygen used changes the volume of gas.
- Capillary tube
- A very thin glass tube in which a drop of coloured liquid moves as the volume of gas changes.
- Oxygen consumption
- The volume of oxygen used by organisms in a given time, a measure of the rate of aerobic respiration.
- Independent variable
- The variable that is deliberately changed in an investigation, here the temperature.
- Dependent variable
- The variable that is measured, here the distance moved by the drop of coloured liquid.
- Control variable
- A variable that is kept the same so that it does not affect the result.
- Control tube
- A tube with glass beads or dead seeds instead of living organisms, to show that the movement is caused by respiration.
- Anomalous result
- A result that does not fit the pattern of the other results and is probably caused by an error.