Biology topic 4

• photosynthesis equation


  Carbon Dioxide + Water -----> Glucose + Oxygen

  
  

  6CO2 + 6H2O -----> C6H12O6 + 6O2
• where does photosynthesis take place

  Chloroplast

  
  

  Chloroplasts use energy from light to transform carbon dioxide and water into glucose and oxygen.
• How plants use glucose

  RESPIRATION- transfers energy from glucose

  MAKING CELLULOSE- to make strong plant cell walls

  MAKING AMINO ACIDS- glucose and nitrate ions make amino acids which are then turned into proteins

  STORED AS FATS OR OILS - glucose is turned into lipids for storing in seeds

  STORED AS STARCH- stored in stems, roots and leaves to use when photosynthesis isn't occurring
• Limiting factors of photosynthesis

  LIGHT INTENSITY (at night)

  CARBON DIOXIDE CONCENTRATION (warm and bright)

  TEMPERATURE (winter)

  
  

  amount of CHLOROPHYLL can also be a limiting factor
• light on rate of photosynthesis

  
• CO2 on rate of photosynthesis

  
• Temperature on rate of photosynthesis

  
• rate of photosynthesis: light intensity and temperature

  
• rate of photosynthesis: light intensity and CO2 levels

  
• Rate of photosynthesis: practical apparatus

  
• light intensity on rate of photosynthesis practical

  1) place light source a set distance away from pondweed.

  2) leave pondweed to photosynthesise for a set period of time (about 5 mins)

  3) count the number of oxygen bubbles produced in a minute

  or

  3) use ruler and measure length of gas bubble

  4) control variables = temp and time

  5) repeat with light source at different distances
• CO2 on rate of photosynthesis practical


  1. Set up a test tube rack containing a boiling tube filled with sodium hydrocarbonate 10 cm away from the light source

  2. Gently push pondweed into boing tube with the cut end uppermost

  3. Leave the pondweed for 5 minutes

  4. Count how many bubbles there are after 1 minute and calculate mean
• why greenhouses are used

  - trap suns heat - ensure temp is not limiting.

  - may use heater (in winter) or ventilation (in summer)

  - commercial farmers often supply artificial light

  - can also increase CO2 levels

  - easier to keep free from pests and disease

  - easy to add fertilisers

  HOWEVER

  - is expensive - need to find the correct amount so to not waste money
• what is respiration


  The process of transferring energy from glucose which goes on in every cell
• How energy from respiration is used

  - build up larger molecules (from smaller ones)

  - allow muscles to contract

  - keep body temperature steady
• What is metabolism


  The sum of all the reactions in a cell or the body
• AEROBIC respiration equation


  glucose + oxygen -> carbon dioxide + water
• aerobic respiration


  - Respiration that requires oxygen

  - happens all the time in plants and animals

  - inside mitochondria
• ANAEROBIC respiration equation


  glucose → lactic acid (+ energy released)
• anaerobic respiration


  - Respiration that does not require oxygen

  - incomplete breakdown of glucose

  - produces lactic acid

  - does not transfer as much energy

  - only useful in emergencies (e.g. when exercising)
• Anaerobic respiration in plants and yeast

  Glucose --> ethanol + carbon dioxide
• what is anaerobic respiration in yeast called


  fermentation
• Anaerobic respiration in yeast uses

  - make bread and alcoholic drinks

  - bread making: CO2 makes bread rise

  - Beer/wine making: fermentation produces alcohol
• Oxygen debt


  the amount of extra oxygen required after physical exercise to convert accumulated lactic acid to glucose.

  TO COUNTERACT THIS:

  - keep breathing heavily to get more oxygen

  - pulse and breathing rate stay high
• Investigating the effect of exercise on the body

  take pulse after:

  sitting down for 5 mins,

  then after 5 mins of walking,

  then after 5 mins of jogging,

  then after 5 mins of running

  and plot results in bar chart

  
  

  Reduce any random errors do it as a group and find an average.