Photosynthesis and Plant Adaptations Lecture Notes

Introduction

• Special Abilities of Organisms: Daydreaming about having abilities like flying (peregrine falcon) or wall-walking (Texas banded gecko).
• Unique Ability of Plants: Photosynthesis.
  • Not only plants perform photosynthesis; some protists and bacteria do too.
  • Plants are the focus as they are major producers in food webs, essential for oxygen production and as a source of food and medicine.

Photosynthesis Overview

• Purpose: Plants make their own food, specifically glucose, through photosynthesis.
• Equation Similarity: Photosynthesis and cellular respiration have similar inputs and outputs but are not simply reversed.
• Glucose: Essential for cellular respiration; plants produce it internally.

Light Absorption and Pigments

• Light Capture: Plants use pigments to capture light.
  • Visible light consists of various wavelengths and colors.
  • Chlorophyll: Absorbs red and blue light but reflects green, making plants appear green.
• Pigments: Other pigments besides chlorophyll capture different light wavelengths, contributing to plant color variation.

Photosynthesis Process

• Chloroplasts: Site of photosynthesis, containing chlorophyll.
• Two Major Reactions:
  1. Light-Dependent Reactions:
     • Occur in the thylakoids (stacks called grana).
     • Capture light and split water to produce electrons, protons, and oxygen.
     • Produce ATP and NADPH needed for the next reaction.
  2. Light-Independent Reactions (Calvin Cycle):
     • Occur in the stroma (fluid outside thylakoids).
     • Do not require light but use ATP and NADPH from light-dependent reactions.
     • Process involves carbon fixation, transforming inorganic CO2 to organic forms with an enzyme's help.
     • Ultimately results in glucose production.

Plant Adaptations for Photosynthesis

• Variety of Adaptations:
  • Leaf shapes, coverings, and pigments adapted for efficient photosynthesis.
• Example: CAM Photosynthesis:
  • Adaptation for hot environments, like deserts.
  • Stomata open at night to minimize water loss, storing CO2 for daytime use.

Conclusion

• Importance of Photosynthesis: Vital for plant survival and ecosystem health.
• Further Reading: Additional resources available for in-depth understanding.
• Encouragement: Stay curious about the wonders of plant biology and photosynthesis.