Photosynthesis Lecture Notes

Introduction

• Objective: Understand what happens in photosynthesis and the factors affecting its rate.
• Nature: Photosynthesis is an endothermic reaction, meaning it requires energy (light energy).

Key Concepts of Photosynthesis

• Energy Source: Plants use light as their energy source.
• Location: Photosynthesis occurs in plant leaves.
• Chlorophyll: A green chemical in leaves that absorbs light energy.

Photosynthesis Reaction

• Inputs: Carbon dioxide (CO₂) and water (H₂O).
• Process:
  • Light energy absorbed by chlorophyll.
  • Converts CO₂ and H₂O into glucose (C₆H₁₂O₆).
• Outputs: Glucose and oxygen (O₂).
• Word Equation: Carbon dioxide + Water → Glucose + Oxygen
• Chemical Formulas: Required to recognize but not balance for exams.

Factors Affecting Photosynthesis Rate

Light Intensity

• Initial Observation: Rate of photosynthesis is zero without light.
• Impact of Increase:
  • As light intensity increases, the rate of photosynthesis increases.
  • Indicates light was a limiting factor.
• Plateau: Past a certain point, increases in light do not increase photosynthesis rate, implying another limiting factor.

Carbon Dioxide Levels

• Observation: Similar pattern as light intensity.
• Limiting Factor: Initially, CO₂ is limiting; eventually, something else becomes limiting.

Chlorophyll Amount

• Effect: Leaves with less chlorophyll trap less light, resulting in a reduced rate of photosynthesis.

Temperature

• Effect:
  • Increasing temperature speeds up enzymes, increasing the photosynthesis rate.
  • Excessive temperature causes enzyme denaturation, reducing the rate.

Conclusion

• Be able to describe the process of photosynthesis and its limiting factors.
• Recommended to review additional questions found in related study materials.