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Biology Unit 2

OCR GCSE 21st Century Science Unit 2 B4, B5, B6

What do plant cells have that animal cells don't? Cell wall, vacuole, and chloroplasts
What is a cell wall in a plant cell made from? cellulose
what does the vacuole contain? a weak solution of sugar and salts
what are chloroplasts for? photosynthesis
what is different about a bacteria? they have no nucleus or mitochondria
what do bacteria have instead of a nucleus? they have a circular molecule of dna floating around the cytoplasm
what are enzymes? biological catalysts
what happens to an enzyme in too hot conditions? the bonds holding the enzyme together will break so that the active site changes shape and so the substrate will not fit- denaturing
what happens to an enzyme when the pH is too high or too low? it interferes with the bonds holding the enzyme together, changing the active site- denaturing
what is respiration? a series of chemical reactions that release energy by breaking down large food molecules
what is the energy from respiration used for? movement, active transport and synthesis of large molecules
what is the symbol of equation for aerobic respiration? glucose + oxygen - carbon dioxide + water (+ energy)
how does aerobic respiration compare to anaerobic in terms of energy released? aerobic respiration releases more energy per glucose molecule
where does anaerobic respiration take place? animal cells, plant cells, bacterial cells
when might you use anaerobic respiration? vigorous exercise when your body can't supply enough oxygen to your muscle cells
when might a plant use anaerobic respiration? in waterlogged soil where the roots have no oxygen
when might bacteria cells use anaerobic respiration? in wounds under the skin where there is little oxygen
what can anaerobic respiration produce in animals? lactic acid
what does anaerobic respiration produce in plant cells and yeast? ethanol and carbon dioxide
what is fermentation? when microorganisms break down sugars into other products by anaerobic respiration
what is fermentation used for? Biogas, bread making and alcohol
how is biogas made? fermentation of carbohydrates to produce methane and carbon dioxide
how does bread rise? yeast ferment carbohydrates releasing carbon dioxide, causing the read to rise
how is alcohol made? yeast ferments sugar to form ethanol
where does photosynthesis occur? the cells of the green parts of plants and some microorganisms such as phytoplankton
why does photosynthesis only happen if plants are green? it requires chlorophyl, which absorbs sunlight and allows the energy to used to convert carbon dioxide and water into glucose
what is the equation for photosynthesis? carbon dioxide + water - glucose + oxygen
how do plants use glucose? respiration, growth, and energy stores
how is glucose used for plant growth? glucose is converted into cellulose, or combined with nitrogen to make amino acids for proteins, or to help make cholorphyll
how is glucose used for plant energy stores? glucose is stored as starch for times when photosynthesis rate is slower, like in winter
what are the three factors that affect photosynthesis? light, carbon dioxide, and water
how does light affect the rate of photosynthesis? the rate of photosynthesis will only increase to the optimum rate, when it no longer is a limiting factor
how does carbon dioxide affect the rate of photosynthesis? the rate of photosynthesis will only increase to the optimum rate, when it is no longer a limiting factor
how does temperature affect rate of photosynthesis? too low temperatures will slow down the enzymes, and too hot will denature the enzymes needed for photosynthesis, usually about 45degrees C
Created by: seymg2011



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