bioenergetics

• what is photosynthesis?

  process by which plants manufacture carbohydrates from raw materials using light energy.
• what are the reactants of photosynthesis?

  carbon dioxide and water
• what are the products of photosynthesis?

  glucose and water
• what is the equation for photosynthesis?


  6CO2 + 6H20 --- C6H12O6 + 6O2
• How are the reactants for photosynthesis obtained?

  CO2 will diffuse from the air into the stomata

  H2O is absorbed from the soil by the roots
• What type of reaction is photosynthesis and why?

  endothermic

  light energy is taken in by the chloroplasts from the environment and light energy is trapped by chlorophyll
• What factors affect the rate of photosynthesis?

  Temperature

  light

  CO2 concentration

  number of chloroplasts
• How does temperature affect the rate of photosynthesis?

  at higher temperatures particles have more kinetic energy

  meaning CO2 and H20 can travel faster through a plant

  Increasing the rate of successful collisions between reactants and enzymes

  resulting in the formation of products
• How does light intensity affect the rate of photosynthesis?

  A higher intensity of light more light is available to carry out photosynthesis

  meaning the more light a plant receives , the faster the rate of photosynthesis
• How does CO2 concentration affect the rate of photosynthesis?

  CO2 is one of the raw materials required for photosynthesis

  meaning the more CO2 present , the faster the reaction can occur

  increasing the rate of photosynthesis
• How does the number of chloroplasts affect the rate of photosynthesis?

  Chloroplasts contain chlorophyll

  which absorb the light energy for photosynthesis

  meaning more chloroplasts means light energy can be absorbed more quickly

  increasing the rate of photosynthesis
• what is the number of chloroplasts affected by?

  diseases

  lack of nutrients

  loss of leaves
• what is the inverse square law?

  light intensity=1/distance^2
• What is the relationship between light intensity and distance?

  As distance increases light intensity decreases

  this means they are inversely proportional
• How do farmers control the rate of photosynthesis in greenhouses and why is this beneficial?

  By only using the minimum levels of heat, water, light and nutrients

  which reduces costs
• What are the five ways glucose is used in plants?

  really - energy for respiration (aerobic and anaerobic)

  silly - insoluble starch for storage (in stems, leaves and roots)

  fat - fats and oils for storage (in seeds)

  cunts - cellulose to strengthen cell wall

  never - combined with nitrate ions to produce amino acids

  provide - for protein synthesis ^^
• what is respiration?

  a chemical reaction that takes place in all living organisms to transfer energy from glucose
• what type of reaction is aerobic respiration?

  Exothermic
• How is oxygen used in aerobic respiration?

  To break down nutrient molecules to release energy (e.g glucose)
• What are the uses of aerobic respiration in humans?

  P - protein synthesis

  A - a constant body temperature

  P - passage of nerve impulses

  A - active transport

  C - cell division and growth

  M - muscle contraction
• What is the equation for aerobic respiration?

  C6H12O6 + 6O2 ---> 6CO2 + 6H2O
• What are two differences between aerobic and anaerobic respiration?

  . Less energy released in anaerobic

  . no oxygen needed in anaerobic
• When does anaerobic respiration occur?

  When the body cant provide enough oxygen so glucose is incompletely broken down

  (e.g in vigorous exercise)
• What is glucose incompletely broken down into in animals during anaerobic respiration?

  Lactic acid
• What is glucose incompletely broken down into in yeast during anaerobic respiration?

  Alcohol and carbon dioxide
• What is anaerobic respiration?

  The incomplete breakdown of glucose without oxygen
• Why is there an increase in demand for oxygen during exercise?

  Muscle contraction requires energy from respiration

  Aerobic respiration requires oxygen

  Number of contractions increases --> demand for oxygen for respiration increases
• How does the body react to the higher demand for oxygen for aerobic respiration during exercise?

  Increase in breathing rate - to increase amount of oxygen absorbed into the bloodstream via diffusion

  and amount of carbon dioxide removed (as there is more produced in aerobic respiration)

  Increased heart rate - to increase supply of oxygenated blood to the muscles
• why is lactic acid formed during anaerobic respiration?

  glucose is not completely oxidised
• What is oxygen debt?

  The amount of extra oxygen needed to react with the lactic acid built up in cells due to anaerobic respiration to remove it from these cells
• How is lactic acid dealt with in the body?

  Oxygen reacts with lactic acid to form carbon dioxide and water --> the same as in aerobic respiration

  Lactic acid is transported to the liver by blood flowing through the muscles where it is converted back into glucose
• What is metabolism?

  The sum of all reactions in a cell or the body
• What are metabolic reactions used for?

  synthesising new molecules
• What is glucose used in the synthesis of?

  Starch - energy storage in plants

  glycogen - storage in liver and muscle cells

  cellulose - to strengthen plant cell walls
• What is glycerol used in the synthesis of?

  Combined with 3 fatty acids in the synthesis of lipids
• What are amino acids used in the synthesis of?

  Proteins
• What is involved in the production of amino acids?

  glucose and nitrates
• What are excess proteins broken down into?

  Urea - excreted from the body