Biology Revision Essay

5670 WordsSep 21, 201423 Pages
Biology BASICS All living organisms are made from cells – all have some common features Nucleus: * Controls type & quantity of enzymes made by cytoplasm * Regulates chemical changes in cell * Controls cell division * Chromosomes found in nucleus Cell Membrane: * Controls entry + exit of chemical in and out of the cell * Maintains structure of the cell Cytoplasm: * all living material other than the nucleus * Where chemical reactions occur – provide energy and useful substances * Mainly liquid, contains large molecules of fat + protein(s) + enzymes Mitochondria: * Generates ATP from food substances Structures in plant cells Cell wall: * outside cell membrane, made up of cellulose * Non-living, allows H20 + dissolved substances through * Not selective like the membrane Vacuole: * cavity filled with cell sap * Large and central. Pushes against the cytoplasm. * Helps maintain strength of the cell * Lack of H2O, vacuole shrinks, cell loses rigidity – plant wilts Chloroplasts: * contains chlorophyll so that photosynthesis can take place Respiration Aerobic * Takes place in mitochondria - ATP used as energy source for chemical reactions * Oxygen needed for this chemical reaction ( oxidation) GLUCOSE + OXYGEN CARBON DIOXIDE + WATER + ENERGY * Some energy becomes heat:- warm blooded animals, heats body :- cold blooded animals, allows fast movement Anaerobic * In absence of oxygen (Eg) yeast on sugar solution can produce carbon dioxide to produce alcohol ENZYMES ENZYMES GLUCOSE ALCOHOL + CARBON DIOXIDE OR GLUCOSE ATP +

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