Keywords

• Absorb = soak up or take away
• acid = pH of less than 7
• acid = a substance that reacts with alkalis and turns litmus paper red
• aerobic respiration = respiration in which oxygen is used to release energy from substances, such as glucose
• alkali = pH of more than 7
• alkali = reacts with acids and turns litmus paper blue
• alkali metal = Group 1 of the periodic table
• alkali metals are very reactive
• alloy = a metal with one or more other elements added to improve its properties.
• anaemia = a deficiency of iron
• aerobic exercise = exercise where all the energy needed can be supplied by aerobic respiration
• anaerobic respiration = respiration that does not need oxygen
• angle of incidence = angle between incoming light ray and the normal
• angle of refraction = angle between the normal and a ray of light that had been refracted
• anther = male reproductive organ in plants that produce pollen
• artery = blood vessels that carries blood away from the heart
• asexual reproduction = new organisms from one parent only
• alveolus = small pocket in the lungs where gases are exchanged between that air and the blood
• atom = small particles from which all substances are made
• bacterium = a microorganism
• attract = two things pulling towards each other
• balanced force = two forces on an object are the same strength but in opposite directions
• binary fission = when a cell splits into two
• biodiversity = range of different species of organisms in an area
• biofuel = fuel made from plants or animal waste
• blood vessel = a tube that carries blood around the body
• boiling = when a liquid turns into a gas
• boiling point = temperature at which a liquid boils
• bond = a force that holds some atoms tightly together
• breathing = movement of muscles that make the lungs expand and contract
• brittle = not easily bent, not flexible and breaks under force
• bronchus = the trachea splits into two tubes, one bronchus goes to the left lungs the other to the right lung
• byproduct = a substance produced by a chemical reaction that is not the desired product of the reaction
• catalyst = a substance that speeds up a chemical reaction without being used up itself
• capillary = thin-walled blood vessel that carries blood from arteries to veins
• carbohydrate = a nutrient that is used as the main source of energy
• carbon monoxide = poisonous gas produced by carbon burning without enough oxygen
• carpel = female reproductive organs in plants (ovary, style and stigma)
• cell = basic unit of all life. All organism are made of cells
• cell division = splitting of a cell to form two identical cells