BIOLOGY Cells
All living things are made of cells. Animal cells have a nucleus, cytoplasm, cell membrane and mitochondria. Plant cells also have a cell wall (cellulose), chloroplasts (photosynthesis) and a vacuole. Bacteria are prokaryotic — no nucleus.
BIOLOGY Photosynthesis
Plants make glucose using light energy. Chloroplasts absorb light; the green pigment is chlorophyll.
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
BIOLOGY Respiration
Aerobic respiration releases energy using oxygen. Anaerobic respiration (in muscles) produces lactic acid. In yeast it produces ethanol + CO₂ (fermentation).
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy
BIOLOGY Digestion & Nutrition
Digestion breaks food into small molecules. Enzymes are biological catalysts: amylase (starch→glucose), protease (protein→amino acids), lipase (fat→fatty acids + glycerol).
CHEMISTRY Atoms & Elements
An atom has a nucleus (protons + neutrons) and electrons in shells. Atomic number = number of protons. Elements in the same group of the periodic table have the same number of outer electrons.
CHEMISTRY Acids & Alkalis
pH < 7 = acid; pH 7 = neutral; pH > 7 = alkali. Neutralisation: acid + base → salt + water. Universal indicator turns red/orange in acids and blue/purple in alkalis.
CHEMISTRY Reactions & States
The three states of matter: solid, liquid, gas. Changes of state are physical changes. Exothermic reactions release heat; endothermic reactions absorb heat. Conservation of mass: total mass of reactants = total mass of products.
PHYSICS Forces & Motion
Force is measured in Newtons (N). Speed = distance ÷ time. Acceleration = change in velocity ÷ time. If forces are balanced, the object moves at constant speed or stays still.
Speed (m/s) = Distance (m) ÷ Time (s)
PHYSICS Energy
Energy cannot be created or destroyed — only transferred or transformed (conservation of energy). Kinetic energy = energy of motion. Gravitational potential energy = stored energy due to height.
KE = ½mv² | GPE = mgh
PHYSICS Waves & Light
Waves transfer energy without transferring matter. Transverse waves: vibrations perpendicular to direction of travel (light). Longitudinal waves: vibrations parallel (sound). Sound needs a medium; light can travel through a vacuum.