Lecture Notes: Photosynthesis and Plant Adaptations

Introduction

• Discussion on special abilities of organisms
  • Flying like a peregrine falcon
  • Walking up walls like a Texas banded gecko
  • Unique ability of plants: Photosynthesis
    • Produces oxygen, essential for life

Importance of Photosynthesis

• Key process for plant survival and food webs
• Plants, bacteria, and protists can perform photosynthesis
• Produces glucose, a crucial energy source

Photosynthesis Process

• Balanced equation similar to cellular respiration
  • Cellular respiration involves ATP production
  • Inputs of photosynthesis are outputs of cellular respiration and vice versa

Adaptations for Photosynthesis

• Plants capture light using pigments
  • Visible light spectrum, different wavelengths
  • Chlorophyll: absorbs red and blue light, reflects green light
  • Other pigments handle different wavelengths

Photosynthesis Reactions

• Occurs in chloroplasts of plant cells

Light-Dependent Reactions

• Occur in thylakoids (granum/grana)
• Light is captured, water is split to form oxygen, electrons, and protons
• Produce ATP and NADPH for light-independent reactions

Light-Independent Reactions (Calvin Cycle/Dark Reaction)

• Occurs in stroma (fluid outside thylakoids)
• Carbon dioxide enters through stomata, is fixed into an organic form
• Uses ATP and NADPH from light-dependent reactions to convert CO2 into glucose

Adaptations in Photosynthesis

• Plant adaptations for different environments
  • Diversity in leaf shapes, coverings, and pigments
• Example: CAM Photosynthesis
  • Used by cacti to conserve water in hot climates
  • Captures CO2 at night to avoid opening stomata during the day

Conclusion

• Photosynthesis is a complex and vital process
• Plants have evolved various adaptations to optimize photosynthesis in diverse environments
• Encouragement to continue exploring the details of photosynthesis