Bioenergetics (biology paper 2)

• Chlorophyll absorbs energy which is used for photosynthesis
• Photosynthesis takes place in The choloroplast
• Carbon dioxide + water ➔ glucose + oxygen
• 6CO2 + 6H2O ➔ C6H12O6 + 6O2
• Photosynthesis is an endothermic reaction
• glucose can be used for respiration and can also be stored as starch
• Plants get carbion dioxide which is needed for photosynthesis by diffusion it diffuses from the air into the leaves via the stomata
• Plants get water from the soil into the root hair cells by osmosis
• Starch is used a long term storage molecul as

  • It is compact
  • it is insoluble in water
  • can be easily Broken down when needed
• Plants need glucose + nitrate ions to make amino acids
• Plants need glucose:

  • Cellular respiration - break down the glucose to release energy 
  • Make cellulose - which is used to make strong cell walls
  • Make starch - which is used to store glucose for a later time
  • Make amino acids - which are used to make proteins 
• Plants might not produce enough chlorophyl:

  • Lack required nutrients
  • May have a disease (TMV)
• 3 factors that affect the rate of photosynthesis:

  • Light intensity
  • Amount of carbon dioxide
  • temperature
• the rate of photosynthesis varies with temperature:

  • When temperature rises the rate of photosynthesis also increases as the particles have more energy and they can move quickly- they can react quicker
  • Once the temperature reaches it optimum temperature the enzymes involved may start to break down and eventually denature
• Farmers in cooler climates often use greenhouses. These help trap the heat energy from sunlight, and so increase the temperature. They also keep out pests which could otherwise damage the plants. 
• Farmers use artificial lighting to make sure photosynthesis takes place 24 hours a day
• Paraffin heaters have 2 benefits

  • releases lots of heat
  • Releases lots of carbon dioxide
• Respiration is the release of energy from sugar molecules such as glucose
• Respiration is an exothermic reaction
• 3 ways cells use the energy from respiration

  • to combine smaller molecules to make larger molecules
  • for muscle contraction
  • To maintain body temperature
• Metabolism is the combination of all chemical reactions in an organism 
• Aerobic respiration equation

  Glucose + oxygen ———> carbon dioxide + water
• Glucose is converted to lactic acid during respiration in animals
• Word equation for anaerobic respiration in plants and fungi

  Glucose ———> ethanol + carbon dioxide
• Why animal cells prefer aerobic respiration and not anaerobic respiration

  • anaerobic respiration doesn’t break down the glucose molecules completely so it releases less energy
  • Anaerobic cells produce lactic acid which can damage cells
• why plants may not produce enough chlorophyl:

  • lack required nutrients
  • have a disease like TMV
• 3 environment factors that affect rate of photosynthesis

  • light intensity
  • Amount of carbon dioxide
  • temperature
• Limited factor in photosynthesis

  • Temperature
  • carbon dioxide concentration
• Farmers in cooler climates often use greenhouses. These help trap the heat energy from sunlight, and so increase the temperature. They also keep out pests which could otherwise damage the plants. 
• Farmers can use artificial lighting me sure photosynthesis takes 24 hours a day
• Paraffin heated have 2 benefits as it releases

  • Heat
  • carbon dioxide
• 1. In order to move during exercise, we have to contract and relax our muscles. 
  2. Muscular contraction requires energy though, which has to be released by cellular respiration. 
  3. Most of the time cells carry out aerobic respiration, which is far more efficient but requires oxygen. 
  4. This means that we have to pump oxygen around the body faster when we exercise. 
  5. As a result we increase both our heart rate and our breathing rate.
• aerobic respiration requires aerobic respiration
• anaerobic respiration leads to oxygen debt
• the liver removes the lactic acid from the blood
• to measure someones breathing rate, we have to count how many times their chest rises and falls in a given amount of time