UNIT 2 TRANSPORT

• Exothermic reaction


  Transfers energy to the surroundings (e.g. respiration)
• Tissue


  A group of similar cells with similar functions
• Organs


  Different tissues working together
• Organ system


  Many organs that work together to perform a particular function
• Artificial pacemaker


  Electrical device used to correct irregularities in the heart rate
• Alveoli


  Air sacs in the lungs
• Arteries


  Carry blood away from the heart; thick muscular walls to keep the blood under high pressure
• Veins


  Carry blood to the heart; thin wall to keep blood under low pressure; have valves
• Capillaries


  Tiny blood vessels with very thin walls to allow substances to diffuse between the blood and other tissues
• Plasma


  Transports proteins and other chemicals around the body
• Red blood cells


  Carry oxygen using a chemical called haemoglobin
• White blood cells


  Help to protect the body against infection
• Platelets


  Fragments of cells which initiate clotting at wound sites
• Synapse


  A gap between two neurones
• Neurone


  A nerve cell that carries electrical impulses
• Receptor


  Cells that detect changes in the environment
• Aerobic respiration provides energy for all living things so that they can contract muscles, maintain body temperature and maintain their metabolism (breaking down and building up molecules)
• Anaerobic respiration releases less energy than aerobic respiration and happens when insufficient oxygen is supplied
• Unicellular organisms have large surface area to volume ratios with allows gases to diffuse directly into them efficiently, with no need for gaseous exchange systems
• The heart contains valves to stop blood flowing backwards
• A group of cells called the 'pacemaker' are found in the right atrium and they control resting heart rate
• Digestive enzymes break down large molecules in food into small, soluble molecules that can be absorbed into the blood
• Carbohydrates (long chains of glucose molecules) – e.g. starch - are broken down by carbohydrase enzymes into glucose to be used for respiration
• Lipids (fats and oils) are broken down by lipase enzymes into fatty acids and glycerol (used as a source of energy)
• Proteins are broken down by protease enzymes into amino acids (used to make new proteins)
• The liver breaks down unwanted amino acids into urea which is excreted as urine by the kidneys
• Benedict's solution turns from blue to brick-red in the presence of sugar, when heated
• Iodine turns black in the presence of starch
• Biuret reagent turns purple in the presence of protein
• Sudan(III) forms a red layer on top if fat is presence; ethanol goes cloudy if fat is present
• Negative feedback mechanisms in the body occur to stabilise a system; when there is a change in the system this leads to a response which reverses the change
• Effector


  A gland/muscle that responds to a change in the environment
• Endocrine system


  Glands that secrete hormones into the bloodstream
• Hormone


  Large molecules carried in the blood to a produce an effect in a target organ
• Pituitary gland


  Master gland in the brain that secretes several hormones
• Adrenaline


  Hormone produced by the adrenal gland to prepare the body for 'fight or flight'
• Thyroxine


  Hormone produced by the thyroid gland to play an important role in growth
• Meristem tissue


  Contains the cells in the plant that divide as the plant grows
• Differentiation


  When cells change to become a specific type of cell (specialise)
• Xylem tissue


  Hollow tubes made of dead cells that carry water and mineral ions from the roots to the leaves