In-Depth Plant Structure and Function Notes

  • Module Overview

    • Focus: Structures and functions of plant cells and tissues.

  • Key Vocabulary

    • Epidermis: Outermost layer of cells covering the plant.
    • Guard Cell: Cells that regulate the opening and closing of stomata.
    • Xylem: Vascular tissue for water and mineral transport.
    • Phloem: Vascular tissue for food transport.
    • Various other terms related to plant structures and responses like root cap, cortex, transpiration, tropism, etc.

  • Plant Cells

    • Characterized by a cell wall and large central vacuole.
    • Types of plant cells include:
    • Parenchyma cells:
      • Functions: Storage, Photosynthesis, Gas exchange, Protection, Tissue repair.
    • Collenchyma cells:
      • Functions: Support, Transport.
    • Sclerenchyma cells:
      • Functions: Support and flexibility for the plant, Tissue repair.

  • Plant Tissues

    • Group of cells performing a function.
    • Four main types of tissues:
    • Meristematic: Involved in growth.
    • Dermal: Protective outer layer.
    • Vascular: Transport tissues (Xylem and Phloem).
    • Ground: Functions like photosynthesis and storage.

  • Meristematic Tissues

    • Types based on position:
    1. Apical meristem: Increases height of plant.
    2. Intercalary meristem: Increases internode length.
    3. Lateral meristem: Increases girth of plant.

  • Dermal Tissue

    • Epidermis: Protective layer with structures like stomata, trichomes, and root hairs.
    • Stomata: Openings for gas exchange regulated by guard cells.
    • Root hairs: Increase surface area for absorption.

  • Vascular Tissues

    • Xylem:
    • Composed of vessel elements and tracheids for water transport.
    • Vessel elements are more efficient than tracheids.
    • Phloem:
    • Composed of sieve tube members and companion cells for food transport.

  • Ground Tissues

    • Composed of parenchyma, collenchyma, sclerenchyma cells.
    • Functions: Photosynthesis, storage, support.

  • Roots

    • Types of roots:
    • Taproot system: Anchors plant, storage (e.g., carrots).
    • Fibrous root system: Rapid water storage and anchorage.
    • Anatomy includes:
    • Root cap: Protects root as it grows.
    • Cortex: Storage and transport function.
    • Endodermis: Regulates water movement.
    • Pericycle: Produces lateral roots.

  • Stems

    • Support for leaves and reproductive structures.
    • Herbaceous vs. woody stems: Herbaceous are flexible, woody are rigid.
    • Types: Tuber, rhizome, runner, bulb, corm - all have varying functions like food storage and reproduction.

  • Leaves

    • Functions primarily in photosynthesis.
    • Structure includes petiole, blade, veins, and specific tissue types like palisade and spongy mesophyll.
    • Types: Simple (undivided) vs. compound (divided into leaflets).

  • ### Plant Responses

    • Nastic Responses: Movement not dependent on stimulus direction (e.g., Venus flytrap).
    • Tropisms: Growth responses toward (positive) or away (negative) from stimuli (light, gravity).
    • Types of tropism include phototropism, gravitropism, and thigmotropism.