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N5 Biology U3KA3 - Photosynthesis and Limiting Factors

May 14, 2024

Photosynthesis and Limiting Factors 🌱

Introduction

  • Focus on photosynthesis, often seen as difficult but manageable when broken down into sections.
  • Basic photosynthesis equation: Water + Carbon Dioxide + Light Energy (chlorophyll) → Oxygen + Sugar (glucose).
    • Oxygen: Released into the atmosphere for us to breathe.
    • Sugar: Used by the plant for energy and growth.

Key Concepts

Plant Cells and Chlorophyll

  • Chloroplasts: Plant cells contain chloroplasts with green pigments called chlorophyll.
  • Chlorophyll: Absorbs light energy, crucial for photosynthesis.

Stages of Photosynthesis

  • Two stages: Light Reactions and Carbon Fixation.

Stage 1: Light Reactions

  • Capturing Light Energy:
    • Sunlight captured by chlorophyll in the chloroplasts.
    • Light energy converted into chemical energy (ATP).
  • Photolysis of Water:
    • Water (Hâ‚‚O) splits into hydrogen and oxygen.
    • Hydrogen: Used in stage 2.
    • Oxygen: Released as a by-product.

Stage 2: Carbon Fixation

  • Enzyme-Controlled Reactions:
    • Involves using hydrogen and ATP (from Light Reactions) + Carbon Dioxide (from atmosphere) to produce sugar.
  • Sugar Utilization:
    • Energy Source: For respiration to make more ATP.
    • Stored Energy: Converted to starch for storage.
    • Building Material: Converted to cellulose for cell walls.

Limiting Factors of Photosynthesis

  • Definition: Factors that can slow down the rate of photosynthesis.
  • Three Main Limiting Factors:
    • Carbon Dioxide Concentration: Essential for stage 2; higher concentration increases rate up to a saturation point.
    • Light Intensity: More light increases rate up to a saturation point where other factors become limiting.
    • Temperature: Enzymes work better up to an optimum temperature; too high temperatures denature enzymes, slowing down photosynthesis.

Exam Tips

  • Always specify correct terms: 'light intensity', 'carbon dioxide concentration'.
  • Understand and be able to explain graphs showing the effects of these limiting factors.

Summary

  • Know the stages of photosynthesis, what occurs in each stage, the fate of the produced sugar, and the limiting factors.
  • Review quizzes and other resources provided to solidify understanding.

Conclusion

  • Clear understanding of the components and processes of photosynthesis essential for exams.
  • Additional resources will be provided to aid study and exam preparation.

Full transcript