bioenergetics

• photosynthesis equation?

  carbon dioxide + water -> glucose + oxygen
• what kind of reaction is photosythesis?

  an endothermic reaction in which energy is transferred from the environment to the chloroplasts as light.
• photosynthesis symbol equation?

  6co2 + 6h2o -> c6h12o6 + 6o2
• pondweed practical?

  this practical is to investigate the effect of light intensity on the rate of photosynthesis. you will increase the distance of the lamp from your pondweed and record how many bubbles you observe within 30 seconds. do three counts at each distance then calculate the mean number of bubbles per minute.
• what is a limiting factor?


  a factor that can limit the amount of photosynthesis a plant can manage.
• why do plants need carbon dioxide?

  to make glucose
• what can the glucose produced in photosynthesis be used for?
• what can the glucose produced in photo synthesis be used for?

  respiration, converted into insoluble starch for storage, to produce fat or oil for storage, produces cellulose which strengthens the cell wall, to produce amino acids for protein synthesis.
• how do plants produce proteins?

  they use nitrate ions that are absorbed from the soil.
• how does temp affect rate of photosynthesis?

   As temperature increases the number of collisions increases, therefore the rate of photosynthesis increases. However, at high temperatures, enzymes are denatured and this will decrease the rate of photosynthesis.
• how does CO2 conc affect rate of photosynthesis?

  Carbon dioxide is one of the reactants in photosynthesis. If the concentration of carbon dioxide is increased, the rate of photosynthesis will therefore increase. 
• how does light intensity affect rate of photosynthesis?

  The rate of photosynthesis is directly proportional to the light intensity until another factor becomes limiting.
• limiting factors?

  these factors interact and any one of them may be the factor that limits photosynthesis.
• why are limiting factors important economically?

  they are important in the economics of enhancing conditions in greenhouses to gain maximum rate of photosynthesis while still maintaining profit.
• what is cellular respiration?

  cellular respiration is an exothermic reaction continuously occurring in living cells.
• what do organisms need energy for?

  chemical reactions to build larger molecules, movement, keeping warm
• aerobic respiration?

  glucose + oxygen -> carbon dioxide + water
• anaerobic respiration?

  glucose -> lactic acid
• why is less energy transferred in anaerobic respiration?

  as the oxidation of glucose is incomplete in anaerobic respiration much less energy is transferred than in aerobic respiration.
• anaerobic respiration in plants and yeast cells?

  glucose -> ethanol + carbon dioxide
• what is oxygen debt?

  The amount of oxygen required to remove the lactic acid, and replace the body's reserves of oxygen, is called the oxygen debt.
• Metabolism is the term used for all the chemical reactions that go on inside an organism's body.

  These reactions build up molecules, and break them down. They are controlled by enzymes.
• what happens during exercise?

  the heart rate, breathing rate and breath volume increase to supply muscles with more oxygenated blood.
• what happens if insufficient oxygen is supplied in the muscles?

  If insufficient oxygen is supplied anaerobic respiration takes place in muscles. The incomplete oxidation of glucose causes a build up of lactic acid and creates an oxygen debt. During long periods of vigorous activity muscles become fatigued and stop contracting efficiently.
• oxygen debt?

  Blood flowing through the muscles transports the lactic acid to the liver where it is converted back into glucose. Oxygen debt is the amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells.
• what is glucose used for?

  glucose is used for respiration which releases energy for taking in minerals (nitrates needed to make amino acids, by active transport using energy), cell reactions and building new molecules (starch = storage, cellulose = cell walls, lipids = cell membranes)
• what does the liver do?

  it can detoxify poisonous substances like ethanol from alcoholic drinks, passes breakdown products into blood so they can be excreted via kidneys, breaks down old worn out blood cells and stores iron until it needs to synthesise more cells.
• metabolism of carbohydrates?

  synthesis of larger molecules from starch glycogen and cellulose. a breakdown of glucose in respiration to release energy
• metabolism of proteins?

  synthesis of amino acids from nitrate ions and glucose. amino acids used to make proteins
• metabolism of lipids?

  synthesis of lipids from one molecule of glycerol and three molecules of fatty acids.
• what are the uses of glucose in plants?

  • respiration
  • making cellulose - strengthens cell wall
  • making amino acids for protein synthesis
  • stored as insoluble starch
  • stored as fats or oils
• how to optimise a greenhouse?

  • heaters could be used in the winter and in summer shades and ventilation could be used
  • artificial light could be used to help photosynthesis during the night
  • a paraffin heater to increase carbon dioxide
  • keeping plants enclosed helps them stay free from pests and disease
• what is energy from respiration used for?

  • building larger molecules
  • muscles contracting
  • controlling body temperature