B8 Photosynthesis

• Photosynthesis?

  how plants synthesise glucose using light energy from Sun. Light energy converted to chemical energy
• Where does photosynthesis occur?

  chloroplasts in plant leaves. chloroplast contain chlorophyll which absorbs light energy.
• Photosynthesis equation(words)

  carbon dioxide + water -> glucose + oxygen
• Photosynthesis: endothermic or exothermic? why?

  endothermic. light energy transferred from environment to chloroplasts .
• How can you show a plant gives off oxygen during photosynthesis?

  use water plant. collect gas bubbles given off during photosynthesis. gas relights a glowing splint (oxygen test)
• Leaf adaptations for photosynthesis

  1. broad leaves = large surface area. 2. thin leaves = short diffusion distance. 3. chlorophyll = trap light energy. 4. veins = transport water via xylem. take glucose via phloem. 5. guard cells = control opening of stomata for gas exchange and prevent water loss
• Four factors affecting rate of photosynthesis

  temperature. light intensity. carbon dioxide concentration. amount of chlorophyll.
• How does temperature affect rate of photosynthesis?

  increase temperature = increase rate of photosynthesis. after a certain temperature rate decreases as enzymes denatured
• How does light intensity affect rate of photosynthesis?

  increase light intensity = increase rate of photosynthesis
• How does carbon dioxide concentration affect rate of photosynthesis?

  increase carbon dioxide = increase rate of photosynthesis
• How does amount of chlorophyll affect rate of photosynthesis?

  Decrease chlorophyll = decreased rate of photosynthesis
• Limiting factor?

  factor that limits the rate of photosynthesis
• How to calculate rate of photosynthesis?

  pondweed in sealed glass tube filled with water and connected to syringe. oxygen gas produced by weed causes bubble in tube to move. distance moved by bubble is used to calculate volume of oxygen.
• How can farmers increase their profits using their knowledge of photosynthesis limiting factors?

  control temperature, light and carbon dioxide concentration
• What is inverse square law for light intensity?

  light intensity = 1 /distance squared
• How do plants use glucose produced in photosynthesis?

  respiration or convert to starch for storage or produce cellulose for cell walls
• Photosynthesis equation

  $6CO_2\hspace{2mm}+$$\hspace{2mm}6H_2O\hspace{2mm}\longrightarrow\hspace{2mm}C_6H_{12}O_6\hspace{2mm}+$$\hspace{2mm}6O_2$