BIOLOGY- RPA6 photosynthesis

• What should you be able to describe by the end of the video?

  Investigate light intensity's effect on photosynthesis
• What additional concept should higher tier students explain?

  How results are affected by the inverse square law
• What equipment is used to start the experiment?

  • Boiling tube
  • LED light source
  • Sodium hydrogen carbonate solution
  • Pond weed
• Why is an LED light source preferred in the experiment?

  It releases minimal heat affecting temperature
• What should be placed between a normal light bulb and the boiling tube?

  A beaker of water to absorb heat
• What does sodium hydrogen carbonate solution release?

  Carbon dioxide needed for photosynthesis
• What happens after placing the pond weed in the boiling tube?

  It acclimatizes for five minutes
• What gas is produced by the pond weed during photosynthesis?

  Oxygen
• How do you measure the rate of photosynthesis in this experiment?

  Count the number of bubbles produced
• What is done after counting bubbles for one minute?

  Repeat the count two more times
• What is the next step after calculating the mean number of bubbles?

  Repeat the experiment at different distances
• What are the distances used in the experiment?

  10 cm, 20 cm, 30 cm, 40 cm
• What are the main problems with counting bubbles?

  • Bubbles can be too fast to count
  • Bubbles vary in size
• How can the problems with counting bubbles be solved?

  Measure the volume of oxygen produced
• What equipment is used to measure the volume of oxygen?

  A measuring cylinder filled with water
• What happens to the number of bubbles per minute as distance increases?

  It falls by a factor of four
• What is the relationship between distance and light intensity?

  Light intensity falls by a factor of four when distance doubles
• What scientific law explains the relationship between distance and light intensity?

  The inverse square law
• Why does light intensity affect the rate of photosynthesis?

  Less light reduces oxygen bubble production
• What should students be able to do after watching the video?

  • Describe the investigation of light intensity on photosynthesis
  • Explain results affected by the inverse square law (higher tier)