Bioenergetics

• co2 from air enters leaves via diffusion

  water from soil enters roots via osmosis

  sunlight absorbed by chlorophyll

  glucose made in leaves

  oxygen is the waste products as it exists via diffusion
• Equation of photoynthesis

  carbion dioxide + water -> glucose + oxygen
• Balanced photosynthesis equation

  6CO(2) + 6H(2)O -> C6H12O6 + 6O(2)
• Uses of glucose

  -Respiration to release energy

  -Converts to insoluble starch to store glucose

  -Makes fats/oils to store glucose

  -Used to produce cellulose to strengthen cell wall

  -Combines with nitrates from soil forming amino acids and makes proteins for growth
• Is photosynthesis endo/exothermic


  Endothermic

  -Energy transferred from surroundings to chloroplasts via light
• Limiting Factors

  Light intensity

  Carbn dioxide

  Temperature
• How to answer Light intensity and carbion limiting factor graphs

  (Light intensity) is the limiting factor because as (light intensity) increases so does rate of photosynthesis

  No longer limiting factor so temperature/Carbion dioxide is limiting
• why does the rate drop rapidly when temperature is no longer limiting

  Enzymes denature
• What to look for in greenhouse questions

  -Maximises photosynthesis rates

  -Maintains profits eg cost of energy
• How can we measure rate of photosynthesis

  -Pondweed, measuring how many bubbles per minute

  -Volume of oxygen produced per minute
• Pondweed practical

  -Set up lamp, ruler and beaker with water and pondweed

  -Add sodium bicarbonate (Adds CO2 so its not limiting factor)

  -Move the lamp to 10cm, switch on and wait so ROP stabalises

  -Count number of bubbles produced in one minute

  -Change distance each time by adding 10 cm, repeat 4-5 times

  -Repeat
• Control variables of pondweed practical

  -Same pondweed and length

  -Same temperature by using a water bath

  -Same Carbon dioxide concentration

  -Repeat experiment 3 times take a mean excluding anomolies
• other experiments to pondweed

  -Change light intensity by changing brightness of bulb

  -Alter potential difference

  -Change the colour of light using colour filters
• Inverse square law

  light intensity = 1/increase in distance^2
• Respiration provides energy for all living things
• Respiration is exothermic and happens continuously
• process of aerobic respiration

  -Oxygen taken into lungs

  -Glucose taken into small intestines

  -Transported via blood - capillaries

  -Waste products of carbon dioxide and water

  -Releases energy
• Released energy uses

  -Chemical reactions building large molecules

  -Movement (contraction)

  -Keeping warm (exothermic)

  -Active transport of molecules and mineral ions
• What is glucose converted to in animal cells in anaerobic

  lactic acid
• What is glucose converted to in plant and yeast cells in anaerobic

  ethanol and carbon dioxide
• What is the difference in energy between respirations

  anaerobic has much less energy breakdown as oxidation of glucose is incomplete
• response to exercise

  -More energy is needed

  -To provide more energy, breathing rate increases

  -Deeper faster breaths - more oxygen taken into blood for aerobic respiration

  -Heart rate increases

  -High BPM - more oxyginated blood supplied to working muscle cells

  -Releases more energy for contraction
• What happens when there is not enough oxygen

  anaerobic respiration
• Process of anaerobic respiration

  -Glucose is converted to lactic acid

  -Oxygen debt

  -Lactic acid builds up, muscles become fatigued

  -Stop contracting efficiently
• Where is lactic acid transported to

  the liver

  Converts it back to glucose to remove lactic acid from blood
• What is oxygen debt

  Amount of extra oxygen needed after anaerobic respiration to react with lactic acid to remove it from cells
• Metabolism conversions

  Simple sugars <-> complex carbohydrates

  Amino acids <-> proteins

  Fatty acids and glycerol <-> lipids
• Metabolism in plants

  -Glucose converts to starch/cellulose by forming a long chain

  -Glucose combines with nitrate ions to form amino acids
• Metabolism in plants and animals

  lipid molecules from glycerol and 3 fatty acids
• Metabolism in animals

  -Breakdown of excess amino acids to form urea for excretion

  -Conversion of glucose to glycerol by forming cains to store glucose in muscles and liver