Photosynthesis

• What is photosynthesis?

  Photosynthesis is the process by which plants convert sunlight, carbon dioxide, and water into glucose and oxygen.

  Carbon Dioxide + Water → Oxygen + Glucose

  6CO₂ + 6H₂O → 6O₂ + C₆H₁₂O₆
• Where does Photosynthesis take place?

  Within chloroplasts in leaf palisade cells. They contain chlorophyll, a pigment which absorbs light energy.
• State the word equation for Photosynthesis.

  Chlorophyll

  Carbon Dioxide + Water → Glucose + Oxygen

  Light
• State the symbol equation for photosynthesis

  6CO₂ + 6H₂O → 6O₂ + C₆H₁₂O₆
• Is photosynthesis endothermic or exothermic? Explain why.

  Endothermic - energy is transferred from the environment to chloroplasts by light.
• Give examples of leaf adaptations which maximise their rate of photosynthesis.

  Broad leaves, maximse surface area. Thin leaves - short diffusion distance. Chlorophyll present - traps light energy. Veins - transport water to leaves via xylem, remove photosynthesis products via phloem. Air spaces - allow carbon dioxide and oxygen to leave. Guard cell - control opening of the stomata and allow gaseous exhange and prevent water loss through transpiration
• What are the four main factors that affect the rate of photosynthesis?

  Temperature

  Light intensity

  Carbon Dioxide concentration

  Amount of Chlorophyll
• How does temperature affect the rate of photosynthesis.

  Increases the rate of photosynthesis and the kinetic energy of the particle is increased. The rate decreases past a certain temperature as enzymes become denatured.
• How does light intensity affect the rate of photosynthesis?

  They are directly proporitional unless another limiting factor is present.
• How does carbon dioxide affect the rate of photosynthesis?

  Increasing the carbon dioxide concentration increases the rate of photosynthesis as CO₂ is required to make glucose.
• How does the amount of chlorophyll affect the rate of photosynthesis?

  The amount of chlorophyll is directly proportional to the rate of photosynthesis as chlorophyll is required to absorb light energy.
• What is a limiting factor?

  An environmental factor which affects the rate of photosynthesis
• How can farmers use their knowledge of limiting factors to increase their profits?

  Control temperature, light intensity, CO₂ concentration to achieve the greatest amount of photosynthesis causing the maximum growth and therefore the maximum yield.
• Relationship between the distance from light source and light intensity.

  Inverse Square Law - light intensity/distance²
• State the 5 uses of the glucose produced during photosynthesis.

  Respiration

  Starch for storage

  Cellulose for strength

  Amino acids and protein synthesis

  Lipids for energy storage in seeds