Bioenergetics summarised revision notes GCSE AQA

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which denatures the enzyme in the plant so photosynthesis stops. Farmers, to achieve the maximum yield can use a paraffin heater. Light intensity: -The amount of light increases, so does the rate of photosynthesis, but it cannot go higher so light intensity is the limiting factor. At a certain point the rate of photosynthesis speeds up so something is the limiting factor. Farmers can add lights to the greenhouse to deduct the limiting factor. Carbon Dioxide: -Concentration of CO2 increases the rate and photosynthesis also does but not at full capacity so CO2 is the limiting factor but then it speeds up making something else like temperature and light intensity the limiting factor. To eliminate this as a limiting factor, farmers can also use paraffin heaters as they prodcue CO2 when heated. USES OF GLUCOSE: -For respiration -Storage of starch -Makes seeds -Making proteins -Making cellulose Exam question: How do plants get energy for photosynthesis? (2) Aerobic Respiration: - A cellular reaction An exothermic reaction Uses oxygen Mnemonic to remember the uses: Ryan ate sunflower seeds for protein content. Answer: Light is trapped (1) by chlorophyll (1) Needed for : Movement, keeping warm and chemical reactions to build larger molecules Equation Glucose + Oxygen --> Carbon dioxide + water TOP TIP: The respiration equation is the opposite to the photosynthesis equation Exam Question: The heart rate increases during exercise. This increase in heart rate increases blood flow to the muscle. Explain, as fully as you can, why this increase in heart rate is necessary. (4) Model Answer: The blood carries oxygen and glucose and the blood flow also helps takes carbon dioxide away from the body (1) Glucose is needed to perform aerobic respiration (1) Aerobic respiration is needed to release energy (1) Energy is required so our muscles can contract. (1) ANAEROBIC RESPIRATION: Anaerobic respiration doesn't use oxygen and it is important to note that this does not replace aerobic respiration but top it up when your muscles have a lack of oxygen. EQUATION: Glucose -> Lactic acid The oxidation of glucose is incomplete so less energy is released. Lactic acid casues muscle fatigue. What is oxygen debt? Extra oxygen in the body needs to react with the lactic acid to remove it from the cells. This is repaid by breathing hard to get more oxygen in the blood and the heart continues to beat faster to remove the lactic acid from the blood. This is then taken to the liver to convert the excess lactic acid into glucose. Anaerobic respiration in Plant and Yeast cell: Glucose --> Ethanol + Carbon Dioxide This is fermentation and has an economic importance. Because this is needed alcohol and baking industry. METABOLISM : Metabolism is the sum of all the reactions in a cell or in the body. For example respiration, mitosis, photosynthesis, active transport Uses: -Formation of lipids molecules from three molecules of fatty acids and one molecules glycerol Breakdown of excess proteins to form urea for excretion - The use of glucose and nitrate ions to form amino acids which are needed to make proteins Respiration Conversion of glucose to starch