Everything from the 3 lessons of this topic on a few pages: the key idea of each lesson, the diagram to remember, the points to learn and the traps examiners set. Read it, cover it, test yourself.
Respiration is the chemical reactions in cells that break down nutrient molecules to release energy. Organisms use that energy for muscle contraction, protein synthesis, cell division, active transport, growth, the passage of nerve impulses and the maintenance of a constant body temperature. Respiration is controlled by enzymes, so in yeast its rate rises with temperature up to an optimum and then falls as the enzymes are denatured.
Respiration releases energy that is already stored in glucose. Never write that respiration "makes" or "produces" energy, and do not confuse respiration (a chemical process in cells) with breathing (ventilation, moving air in and out of the lungs).
The temperature axis is the independent variable and the carbon dioxide volume is the dependent variable. Do not say the yeast "dies at the optimum": the optimum is where respiration is fastest; it is above the optimum that the enzymes denature.
Aerobic respiration is the chemical reactions in cells that use oxygen to break down nutrient molecules to release energy. Word equation: glucose + oxygen → carbon dioxide + water. Extended: the balanced chemical equation is C6H12O6 + 6O2 → 6CO2 + 6H2O.
Oxygen is a reactant, not a product, and water is a product. Students often swap them when writing the word equation in a hurry. Plants respire aerobically all the time too, in light and in darkness.
Write the formulae exactly: C6H12O6, O2, CO2, H2O. "6O" or "H2O6" loses the mark, and energy is not a substance, so it is not written as a product in the balanced equation.
Anaerobic respiration is the chemical reactions in cells that break down nutrient molecules to release energy without using oxygen. It releases much less energy per glucose molecule than aerobic respiration. In yeast: glucose → alcohol + carbon dioxide. In muscles during vigorous exercise: glucose → lactic acid. Extended: C6H12O6 → 2C2H5OH + 2CO2; lactic acid builds up in muscles and blood, causing an oxygen debt that is repaid after exercise.
Anaerobic respiration in muscles makes only lactic acid: no carbon dioxide and no alcohol. Only the yeast equation has carbon dioxide. Never write "glucose → lactic acid + carbon dioxide".
The balanced yeast equation has two ethanol and two carbon dioxide, and no oxygen on either side. Ethanol is C2H5OH, not CH3OH.
The oxygen debt is the extra oxygen needed after exercise to remove lactic acid, not a shortage of oxygen in the air. Lactic acid is broken down in the liver, and it is carried there by the blood.