Lecture Notes on Photosynthesis and Plant Adaptations

Introduction

• Special abilities of organisms and the speaker's interest in plants' ability to photosynthesize.
• Photosynthesis is not limited to plants; some protists and bacteria can also perform it.
• Importance of photosynthesis:
  • Produces oxygen, essential for animal life.
  • Plants are major producers in food webs and produce glucose.

Photosynthesis Overview

• Plants make their own glucose through photosynthesis.
• Balanced equation of photosynthesis compared to aerobic cellular respiration:
  • Inputs of photosynthesis (e.g., CO2, water) are outputs of cellular respiration.
  • Outputs of photosynthesis (e.g., glucose, oxygen) are inputs of cellular respiration.

Light Capture and Pigments

• Plants use pigments to capture light, mainly chlorophyll.
• Visible light has different wavelengths/colors, affected by pigments.
• Chlorophyll absorbs red and blue light; reflects green light (reason for green appearance of plants).
• Chlorophyll is found in chloroplasts of plant cells.

Photosynthesis Reactions

Light Dependent Reactions

• Occur in thylakoids of chloroplasts (stacks called grana).
• Light is captured, water is split into electrons, protons, and oxygen.
• Produce ATP and NADPH needed for light independent reactions.

Light Independent Reactions (Calvin Cycle)

• Occur in stroma of chloroplasts.
• Carbon dioxide enters through stomata, which plants can open/close.
• Inorganic CO2 is fixed to an organic form.
• ATP and NADPH from light dependent reactions are used.
• Complex pathways convert fixed CO2, ATP, and NADPH into glucose.

Photosynthesis Equation

• CO2 and glucose representation in the Calvin Cycle and light dependent reactions.
• Further details include photosystems and recycling of ATP and NADPH.

Plant Adaptations for Photosynthesis

• Adaptations in leaf shape, coverings, and pigments.
• Example: CAM Photosynthesis in cacti.
  • Cacti open stomata at night to capture CO2, preventing water loss during hot days.

Conclusion

• Importance of understanding photosynthesis and plant adaptations.
• Encouragement to explore more about this process and stay curious.