Photosynthesis and Respiration

Video Summary

• Photosynthesis and Respiration
  • The two are closely related
  • Photosynthesis: Takes in carbon dioxide, releases oxygen
  • Respiration: Takes in oxygen, releases carbon dioxide

Gas Exchange in Plants

• Comparison of Gas Exchange During Day and Night
  • Daytime: Photosynthesis requires light
  • Nighttime: No photosynthesis, only respiration

Experiment 7.9

• Hydrogen Carbonate Indicator

  • Normal atmospheric carbon dioxide concentration is 0.04%
  • Color change: Red (normal) → Yellow (increased carbon dioxide) → Purple (reduced carbon dioxide)

• Experiment Setup

  • Prepare four test tubes, each with 3g of Hydrogen Carbonate Indicator
  • A and C contain leaves
  • A and B are not wrapped in foil (simulate daytime); C and D are wrapped in foil (simulate nighttime)

• Experiment Results

  • A: Turns purple, as leaves absorb carbon dioxide
  • B: Remains red, as there is no change
  • C: Turns yellow, as leaves release carbon dioxide
  • D: Remains red, as there is no change

Summary

• Plant Gas Exchange Depends on the Rates of Photosynthesis and Respiration
  • Daytime: Net carbon dioxide absorption, net oxygen release
  • Nighttime: Only respiration occurs, net oxygen absorption, net carbon dioxide release

Observation of Gas Exchange on Leaf Surface

• Experiment 7.10

  • Use a microscope to observe the surface of the leaf
  • Stomata are the structures for gas exchange
  • The opening and closing of stomata control the in and out movement of gases
  • Chloroplasts and nuclei are near the stomata

• Summary: Plant Gas Exchange Occurs Through Stomata