bioenergetics

• Photosynthesis Produces Glucose Using Light
• Photosynthesis


  Change carbon dioxide and water into glucose and oxygen
• Photosynthesis


  • Takes place in chloroplasts in green plants
  • Light energy is transferred for the process
• The equation for photosynthesis is: carbon dioxide + water -> glucose + oxygen
• Ways plants use glucose

  • For respiration
  • Making cellulose
  • Making amino acids
  • Stored as oils or fats
  • Stored as starch
• Limiting factors


  Factors that can stop photosynthesis from happening any faster (light intensity, CO2 concentration, temperature)
• Chlorophyll can also be a limiting factor of photosynthesis
• Inverse square law


  Light intensity decreases in proportion to the square of the distance
• If you double the distance, the light intensity will be four times smaller
• Greenhouses


  • Help trap the Sun's heat
  • Maintain ideal temperature
  • Provide artificial light
  • Increase CO2 levels
  • Protect from pests and disease
  • Allow addition of fertilisers
• Sorting out the ideal conditions in a greenhouse costs money but allows much faster plant growth and more frequent harvests
• Greenhouse


  • Help to trip the Sun's bast
  • Make sure temperature doesn't become limiting
• Greenhouse temperature control in winter

  Use heater to keep temperature at ideal level
• Greenhouse temperature control in summer

  Use shades and ventilation to cool things down
• Light is always needed for photosynthesis, so commercial farmers often supply artificial light after the Sun goes down to give their plants more quality photosynthesis time
• Increasing carbon dioxide levels in greenhouse

  1. Use paraffin heater to heat the greenhouse

  2. Paraffin burning produces carbon dioxide as a by-product
• Keeping plants enclosed in a greenhouse makes it easier to keep them free from pests and diseases
• Farmers can add fertilisers to the soil to provide all the minerals needed for healthy growth
• Keeping greenhouse conditions just right for photosynthesis


  Plants will grow much faster and a decent crop can be harvested much more often, which can be sold
• It's important that a farmer supplies just the right amount of heat, light, etc. - not more than the plants need, as this would just be wasting money
• An experiment was carried out to find out the effect of temperature on the rate of photosynthesis
• Variables that should have been controlled in the experiment

  • Two variables
• A plant is moved from 15 cm away from the light source


  The rate of photosynthesis changes
• Respiration is NOT "Breathing In and Out"
• Respiration


  The process of transferring energy from glucose
• Respiration happens in plants too, it's how they get energy from their food
• Respiration transfers energy for all kinds of things, like building up larger molecules, allowing muscles to contract, and keeping body temperature steady
• Metabolism


  All the chemical reactions in an organism
• Reactions that happen in metabolism

  • Glucose molecules joining together to form starch, glycogen, and cellulose
  • Lipid molecules made from glycerol and fatty acids
  • Glucose combined with nitrate ions to make amino acids, which are then made into proteins
  • Glucose broken down in respiration
  • Excess protein broken down to produce urea
• Aerobic respiration


  Respiration using oxygen, the most efficient way to transfer energy from glucose
• Aerobic respiration goes on all the time in plants and animals, mostly in the mitochondria
• Anaerobic respiration


  Respiration without oxygen, the incomplete breakdown of glucose
• Anaerobic respiration is used if there's not enough oxygen, like during vigorous exercise
• Anaerobic respiration in muscle cells

  Glucose -> lactic acid
• Anaerobic respiration does not transfer nearly as much energy as aerobic respiration
• Anaerobic respiration in plants and yeast

  Glucose -> ethanol + carbon dioxide
• Anaerobic respiration in yeast cells is called fermentation, which is used to make bread and alcoholic drinks
• In bread-making, the carbon dioxide from fermentation makes the bread rise
• In beer and wine-making, the fermentation process produces the alcohol
• When you exercise, your body responds in different ways to get more oxygen and energy to the muscles