03 Plant Form and Function

General Biology 2: Plant Form and Function

Lesson Overview

• Class Date: February 12, 2025

• Session Topic: Plant Form and Function

• Objectives:

  • Describe characteristics of plant organisms.

  • Identify and describe plant tissues and trace the fate of meristematic tissues.

  • Describe the structure, function, and modifications of major plant organs (roots, stem, leaves, flowers, and fruit).

Characteristics of Plant Organisms

• Kingdom Plantae:

  • Multicellular, photosynthetic, and eukaryotic.

  • Cell walls composed of cellulose.

  • Exhibits alternation of generations (life cycle stages).

  • Well-developed tissues supporting various functions.

  • Stores energy as starch.

Plant Structure

• General Structure:

  • Vegetative Structures:

    • Shoot system (above ground).

    • Root system (below ground).

  • Reproductive Structures:

    • Flowers.

    • Seeds and fruits.

Plant Tissues

• **Types of Plant Tissues: **

  • Meristematic Tissues:

    • Undifferentiated cells capable of division and differentiation (totipotent).

  • Permanent Tissues:

    • Classified into:

      • Simple Tissues:

        • Parenchyma

        • Collenchyma

        • Sclerenchyma

      • Complex Tissues:

        • Xylem

        • Phloem

Meristematic Tissues

• Apical Meristems:

  • Located at the tips of roots and shoots.

  • Responsible for lengthening growth, primary tissue production (protoderm, ground meristem, procambium).

• Lateral Meristem:

  • Increases girth of roots and stems post-maturation (vascular cambium and cork cambium).

• Intercalary Meristems:

  • Found in grasses, contributing to length growth.

Permanent Tissues

• Simple Tissues:

  • Parenchyma: Main component of young plant organs, for storage and photosynthesis.

  • Collenchyma: Provides flexible support.

  • Sclerenchyma: Dead cells providing structural support, examples include fibers and sclereids.

• Complex Tissues:

  • Xylem: Transports water and provides support.

    • Contains tracheary elements, fibers, and parenchyma.

  • Phloem: Transports sugars, consists of sieve tube cells, companion cells, fibers, and parenchyma.

Plant Organs

• Roots:

  • Anchor the plant and absorb/conduct water and minerals.

  • Types include taproot (dicots) and fibrous root (monocots).

  • Modified Roots: Storage roots, buttress roots, climbing roots, pneumatophores, prop roots, root nodules, and strangling roots.

• Stems:

  • Support leaves and buds and facilitate water/solute transport.

  • Can store materials (e.g., water, starch).

  • Modified Stems: Rhizomes, runners/stolons, tubers, bulbs, corms, cladophylls, tendrils.

• Leaves:

  • Photosynthesis, gas exchange, transpiration, and attracting pollinators.

  • Modified Leaves: Bracts, spines, and insect-trapping structures.

• Flowers:

  • Key role in plant reproduction via pollination.

  • Composed of modified leaves: sepals, petals, stamens, and carpels.

• Fruits:

  • Seed-bearing structures formed from ovary post-pollination.

  • Types include simple fruit, aggregate fruit, and multiple fruit.

Recap and Discussion Prompts

• Questions for Class:

  • Discussions on the importance and adaptations of plant structures and their functions.

  • Explore botanical vs. culinary definitions of fruits and vegetables.

Conclusion

• Plant biology focuses heavily on understanding these structures and functions, emphasizing their adaptations for survival in different environments.