Bioenergetics

• What is the equation for photosynthesis?
• What is required to produce glucose molecules by photosynthesis? Energy
• What type of reaction is photosynthesis? Endothermic
• What is endothermic? Takes heat in.
• How is the energy needed by plants for photosynthesis supplied? Sunlight
• How is sunlight trapped? By a green chemical called chlorophyll, which is found in chloroplasts.
• What 4 factors affect the rate of photosynthesis? [4] - Temperature - Carbon Dioxide - Light Intensity - Chlorophyll concentration
• Why does the rate of photosynthesis drop to zero as it approaches 45C? The enzymes controlling photosynthesis have been destroyed.
• What is the limiting factor? The factor that stops the reaction going any faster.
• What 5 ways do plants use glucose? [5] - Respiration - Making cellulose - Making amino acids - Stored as lipids - Stored as Starch
• What is inverse square law? When you half the distance, the light intensity will be four times greater.
• What is the forumula for inverse square law?
• What is respiration? Process of transferring energy from glucose.
• What reaction is respiration an example of? Exothermic
• Why do organism need the energy from respiration? [3] - Chemical reactions to build larger molecules - Movement - Keep warm
• What are the two types of respiration? - Aerobic (with oxygen) - Anaerobic (without oxygen)
• What is the equation for aerobic respiration?
• Why does anaerobic respiration transfer much less eneregy than aerobic respiration? In anaerobic respiration, glucose is not completely broken down. This means that it transfer much less energy than aerobic respiration.
• How is the process of anaerobic respiration different in animals to the process found in plants and yeast? - In animals, lactic acid is produced. - In plants and yeast, ethanol (alcohol) and carbon dioxide is produced.
• What is anaerobic respiration in yeast cells called? Fermentation. This is important in the manufacture of bread and alcoholic drinks.
• Why does the rate of respiration need to increase during exercise? The body demands more energy
• What happens during periods of vigorous activity? The muscles may not get supplied with enough oxygen, so anaerobic respiration starts to take place in the muscle cells.
• What happens when anaerobic respiration begins to take place in the muscle cells? - Causes a build up of lactic acid - Creates oxygen debt
• What does Lactic acid do to the muscles? It causes them to hurt and stops them contracting efficiently. Lactic acid is a poision, so it needs to be removed quickly.
• What is metabolism? Metabolism is the sum of all the chemical reactions in a cell or the body.
• What are metabolic reactions controlled by? They are controlled by enzymes and many need a transfer of energy.
• How is energy transferred to metabolic reactions? The energy is transferred by respiration and use to make new molecules: - Conversion of glucose to starch, glycogen and cellulose - Formation of lipid molecules from a molecule of glycerol and three molecules of fatty acids - Use of glucose and nitrate ions to form amino acids, which are used to synthesise proteins - Breakdown of excess proteins into urea for excretion
• What does oxygen debt mean? The amount of oxygen required to remove the lactic acid, and replace the body's reserves of oxygen,
• What does an increase in the temperature do to the rate of photosynthesis? Increasing the temperature increases the rate of photosynthesis as the kinetic energy of particles is increased.
• Why does decreasing the amount of chlorophyll affect the rate of photosynthesis? Decreasing the amount of chlorophyll decreases the rate of photosynthesis as chlorophyll is required to absorb light energy.
• How does light intensity affect the rate of photosynthesis if increased? Increasing the light intensity increases the rate of photosynthesis until another factor becomes limiting.
• Why is photosynthesis an endothermic reaction? Energy is transferred from the environment to chloroplasts by light.
• How can you show that a plant gives off oxygen during photosynthesis? Using a water plant (eg. Elodea), collect gas bubbles produced during photosynthesis. The gas will relight a glowing splint as it contains oxygen.
• What is photosynthesis? The process by which plants synthesise glucose using light energy from the Sun. Light energy is converted into chemical energy.
• How can farmers use their knowledge of limiting factors to increase their profits? They can control temperature, light intensity and CO2 concentration to achieve the fastest possible rate of photosynthesis, leading to a greater yield.
• Give examples of leaf adaptations which maximise the rate of photosynthesis [6] - Broad leaves - Thin leaves - Chlorophyll present - Veins - Air spaces - Guard cells
• How does broad leaves maximise the rate of photosynthesis? Maximises the surface area
• How does thin leaves maximise the rate of photosynthesis? Short diffusion distance
• How does having chlorophyll present maximise the rate of photosynthesis? Traps light energy
• How do veins maximise the rate of photosynthesis? [2] - Transport water to leaves via the xylme tube - Remove photosynthesis products via phloem tube