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Understanding Leaf Structure and Photosynthesis

May 11, 2025

Lecture Notes: Leaf Structure and Photosynthesis

Overview

  • Focus on the interior structure and function of leaves.
  • Connection to the process of photosynthesis.

Photosynthesis

  • Plants convert carbon dioxide and water into glucose and oxygen using sunlight.
  • Key structures handle reagents and products of photosynthesis.

Types of Leaves

  • Simple Leaves
  • Compound Leaves

Leaf Structure

1. Waxy Cuticle

  • Thin hydrophobic layer on leaf surface.
  • Reduces water loss via transpiration.

2. Upper Epidermis

  • Tightly packed cells.
  • Prevents water loss.
  • Translucent to allow light for photosynthesis.

3. Palisade Mesophyll (Palisade Parenchyma)

  • Major site of photosynthesis.
  • Packed with chloroplasts.
  • Column shaped cells.

4. Spongy Mesophyll (Spongy Parenchyma)

  • Loosely packed cells with intercellular spaces for gas exchange.
  • Contains chloroplasts for some photosynthesis.

5. Vascular Bundle

  • Xylem: Transports water upward from roots.
  • Phloem: Transports photosynthesis products throughout the plant.
  • Bundle Sheath Cells: Allow special photosynthesis in arid environments (C4 photosynthesis pathway).

6. Lower Epidermis

  • Prevents water loss.
  • Contains stomata for gas exchange.
    • Stoma: Allows carbon dioxide in and oxygen out.
    • Guard Cells: Regulate stoma opening based on environmental conditions.

7. Trichomes

  • Hair-like structures on leaf surface.
  • Deter predators and restrict insects.
  • Can store terpenes, which are hydrocarbon-rich and non-soluble.

Photosynthesis and Environmental Adaptation

  • Carbon Fixation: Extraction of carbon from atmosphere into organic carbon.
  • C4 and CAM plants adapt to dry environments with modified photosynthesis processes.

Terpenes

  • Found in lavender, pine, citrus, THC.
  • Non-polar, non-soluble; effective as a defense mechanism.

Conclusion

  • Review of leaf structure and photosynthesis.
  • Encourage to review diagrams and cross-sections for better understanding.

Remember to review any diagrams provided for a visual understanding of leaf structures and their roles in photosynthesis.

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