Bio paper one

• Eukaryotic cells


  Cells that contain their genetic material enclosed in a nucleus
• Eukaryotic cells


  • Contain a nucleus
  • Contain a cell membrane
  • Contain cytoplasm
• Prokaryotic cells


  Cells where the genetic material is not enclosed in a nucleus
• Prokaryotic cells


  • Do not have a nucleus
  • Have a cell membrane
  • Have a cell wall
  • Contain cytoplasm
  • May have plasmids
• Prokaryotic cells


  Are much smaller than eukaryotic cells
• Bacterial cells are an example of prokaryotic cells
• Some bacteria also have pili, which are hair-like structures used for attachment and transferring genetic material during conjugation.
• Bacteria have flagella that allow them to move through their environment by rotating or whipping back and forth.
• Chloroplasts contain chlorophyll which absorbs light energy from sunlight to make glucose during photosynthesis.
• The cell wall provides support to the bacterium and protects it from bursting due to osmosis.
• Photosynthesis


  The reaction that plants use to trap light energy
• Plants use light for their source of energy
• Photosynthesis


  • It is an endothermic reaction
  • It takes place in the leaves of a plant
  • Leaves contain the green chemical chlorophyll
• Photosynthesis


  1. Plant takes in carbon dioxide and water

  2. Light energy is absorbed by chlorophyll

  3. Carbon dioxide and water are converted into glucose

  4. Oxygen is produced
• Chemical formulas


  • Carbon dioxide (CO2)
  • Water (H2O)
  • Glucose (C6H12O6)
  • Oxygen (O2)
• Light intensity increases


  Rate of photosynthesis increases
• Light intensity is a limiting factor


  Photosynthesis is not as fast as it could be because there isn't enough light
• Carbon dioxide level increases

  Rate of photosynthesis increases
• Carbon dioxide is a limiting factor


  Photosynthesis is not as fast as it could be because there isn't enough carbon dioxide
• Temperature increases


  Enzymes involved in photosynthesis work faster, increasing the rate
• Temperature keeps increasing


  Enzymes denature, decreasing the rate of photosynthesis
• Factors that affect the rate of photosynthesis are: light intensity, carbon dioxide level, amount of chlorophyll, and temperature
• Photosynthesis


  Carbon dioxide + water + light energy → Glucose + Oxygen
• Respiration


  Process that releases energy from glucose in the mitochondria
• Photosynthesis only produces glucose during the day


  Plant cells respire all the time, including at night
• Starch


  Insoluble storage molecule made from glucose, which can be converted back to glucose when needed
• Fats and oils


  Storage form of energy made from glucose in many plants
• Cellulose


  Molecule in the plant cell wall, made from glucose, that gives it strength
• Amino acids


  Made from glucose, used by plants to synthesize proteins
• Peas are a good protein source
• Plants need to absorb nitrate ions from the soil to make amino acids from glucose
• Investigating the effect of light intensity on the rate of photosynthesis


  1. Take a boiling tube and place it 10 cm away from an LED light source

  2. Fill the boiling tube with sodium hydrogen carbonate solution

  3. Put a piece of pond weed into the boiling tube

  4. Leave for 5 minutes to acclimatize

  5. Count the number of bubbles produced in 1 minute
• Repeating the experiment at different distances


  1. Repeat the experiment at 20 cm, 30 cm, and 40 cm from the light source

  2. Calculate the mean number of bubbles produced per minute at each distance
• Problems with counting bubbles


  • Number of bubbles can be too fast to count accurately
  • Bubbles are not always the same size
• Measuring the volume of oxygen produced

  1. Place the pond weed in a measuring cylinder filled with water

  2. Measure the volume of oxygen produced
• Doubling the distance from the light source


  The number of bubbles per minute falls by a factor of 4
• Inverse square law


  If the distance is doubled, the light intensity falls by a factor of 4, which causes the number of oxygen bubbles to fall by 4 times
• Limiting factor in photosynthesis


  The factor that is currently restricting the rate of photosynthesis
• Determining the limiting factor in photosynthesis


  1. Increase light intensity

  2. Increase carbon dioxide concentration

  3. Increase temperature
• Increasing light intensity


  Rate of photosynthesis increases initially