bioenergetics

• what do plants use light for?

  energy for photosynthesis
• what type of reaction is photosynthesis?

  endothermic
• what part of the leaf absorbs the light energy

  chlorophyll
• write the word equation for photosynthesis.

  carbon dioxide + water ----> glucose + oxygen
• write the symbol equation for photosynthesis

  co2 + H20 ----> C6 H12 06 + O2
• what happens to the rate of photosynthesis as we increase light intensity?

  Increases (more light energy to carry out reaction quicker)
• what type of factor is light intensity in the photosynthesis graph?

  limiting factor as without the light, photosynthesis takes place
• what does it mean when the graph plateaus (rate of photosynthesis)

  the light intensity is not the limiting factor, new factor added,,,, e.g, carbon dioxide
• name 3 limiting factors of photosynthesis

  1. light intensity
  2. amount of chlorophyll
  3. temperature
• explain how amount of chlorophyll is a limiting factor

  • contracts less light and energy than normal leaves
  • so less SA for photosynthesis
• explain how temperature is a limiting factor to photosynthesis

  • enzymes will work faster in warmer temperatures so rate of photosynthesis increases
  • however, if temperature is too high then enzymes will denature and rate of PS
• name the 4 uses of glucose from photosynthesis

  1. release energy in respiration
  2. produce the insoluble storage- starch
  3. convert it to fats and oils
  4. produce amino acids
• what is the need for glucose to turn into starch in photosynthesis

  • starch can be converted back to glucose at any time
  • useful as plants photosynthesise all day so starch is a good storage source for the night
• why is glucose made in photosynthesis converted into fats and oils?

  energy storage
• what is cellulose (cell walls structure) made out of?

  glucose produced in photosynthesis
• why does glucose made in photosynthesis converted to amino acids?

  used by plant to synthesise protines
• how do plants make amino acids from glucose?

  plants absorb nitrate ions from the soil
• why do farmers want to increase the rate of photosynthesis

  increases the yield of crop they produce
• how do farmers increase the rate of photosynthesis?

  light and heat their greenhouses,,,, also, they add extra carbon dioxide,,,, some use oil burners as it produces heat and carbon dioxide at the same time
• what type of reaction is respiration

  exothermic- because it releases energy
• aerobic respiration word equation is....

  glucose + oxygen -energy-> carbon dioxide + water
• why does aerobic respiration release so much energy?

  because the glucose molecule gets fully oxodised
• chemical equation for aerobic respiration

  C6 H12 O6 + O2 ---> CO2 + H20
• what happens if cells dont have enough oxygen?

  anerobic respiration is carried out
• when do muscle cells respire anaerobically?

  during intense exercise or when oxygen supply is limited
• anaerobic respiration word equation

  glucose ---> lactic acid
• why does anaerobic respiration release less energy than aerobic?

  oxidation of glucose is incomplete so their is less oxygen
• anaerobic respiration in yeast and plant cells equation...

  glucose ---> ethanol + carbon dioxide
• what is anaerobic respiration in yeast cells called.

  fermentation
• what is fermentations ---> uses for drinks

  • to make alcoholic drinks,, e.g, beer
  • the alcohol in these drinks is ethanol
• how does fermentation help bread?

  • the carbon dioxide produced in anaerobic respiration creates bubbles in dough, causing it to rise
• during excercise, why does the body need a great deal of energy

  for muscle contraction
• what happens during exercise

  • aerobic respiration increases
  • breathing rate and volume increases
  • heart rate increases (to pump oxygenated blood around the body)
• what happens during long periods of vigorous activity (e.g.,, exercise)

  lactic acid build up,,, causing muscles to become fatigued,,, stops efficiency of muscle contraction
• explain the stages of oxygen debt

  1. lactic acid is transported out of the muscles by the blood
  2. then, acid is taken to the liver and converted back into glucose in a series of chemical reactions
• define oxygen dept

  the amount of extra oxygen the body needs after exercise to deal with the accumulated lactic acid
• define respiration

  a chemical reaction that releases energy from glucose
• metabolism

  the sum of all chemical reactions in a cell or the body
• define metabolism

  the sum of all chemical reactions in a cell or the body
• what 3 things can glucose be converted into in plants

  1. cellulose
  2. amino acids
  3. starch