Plant Biology: Algae and Non-Vascular Plants

Plant Characteristics

• Living things are compared based on their similarities.
• Everything originated from green algae.
• Plants' closest relative is green algae.

Similarities Between Green Algae and Plants

• Cell Walls:
  • Fungi cell walls are made of chitin.
  • Bacterial cell walls are made of peptidoglycan.
  • Cellulose is the most abundant organic molecule on Earth.
  • Chitin is the second most abundant organic molecule on Earth.
• Energy Storage:
  • Starch is a glucose-based energy storage compound, similar to cellulose.
• Photosynthesis:
  • Plants use chlorophyll a & b for photosynthesis.
• Genetic Similarities:
  • Genetic similarities exist between plants and algae.

Non-Vascular Plants

• Lack veins (vascular tissue).
• Cannot grow large.
• Simple diffusion moves fluids.
• Grow close to the ground.
• Lack of stems and leaves.
• Cannot survive in dry conditions.
• Major generation is the gametophyte.
  • Mosses:
    • Grow in wet areas.
    • Gametophyte is larger than the sporophyte.
    • Photosynthetic.
    • Sporophyte is smaller, non-photosynthetic.
  • Liverworts:
    • Flat body plants.
    • Lie along the mud.
    • Gametophyte is larger than the sporophyte.
    • Photosynthetic.
    • Sporophyte is smaller, non-photosynthetic.

Vascular Plants

• Have vascular tissue.
• Major generation: Sporophyte (large).
• Minor generation: Gametophyte (small).
• Has stems and leaves.
• Primitive Vascular Plants:
  • Selaginella
  • Ferns
  • Horsetails
  • Do not produce seeds, only spores.
• Seed Plants (Gymnosperms):
  • Conifers (pine trees):
    • Produce male pollen cones and female seed cones.
    • Wind disperses pollen.
    • Seeds develop when pollen lands on cones.
    • Seeds drop when mature.
  • Cycads:
    • Plants are either male or female.
    • Females produce seeds.
    • Males produce pollen.
    • Sperm swim to ovules for fertilization and growth.
  • Ginkgo:
    • Sperm cells swim for fertilization and growth.

Organs (Flowering Plants - Angiosperms)

• Lack organ systems, but have organs.
• Roots:
  • Primary/Taproot (first root)
  • Secondary/Branch root
  • Cotyledon (seed leaf): food for seedling before photosynthesis
• Stem:
  • Support and transport.
  • Made of nodes and internodes.
• Leaves:
  • All reproductive parts considered “leaves”
  • Has vascular tissue.
  • Blade (flat, photosynthetic).
  • Petiole (attaches the blade to the stem).
  • Axillary Buds: produce new stems and leaves.
• Dicot Leaf characteristics: -2 seed leaves. -Leaf Veins: branched or net-like pattern. -Flower parts: multiples of four or five. -Vascular bundles arranged in a stem ring. -Taproot system (one main root with smaller roots).
• Monocot Leaf characteristics: -1 seed leaf. -Leaf Veins: parallel pattern. -Flower parts: multiples of three. -Vascular bundles scattered throughout the stem. -Fibrous root system (many small roots spreading out).

Plant Tissues

• Dermal Tissue:
  • Outer layer of any plant organ.
  • Epidermis: thin layer of live cells around the organ.
• Vascular Tissue:
  • Carries water and minerals (xylem) and sugars (phloem).
    • Dicots: Ring of vascular bundles.
    • Monocots: Scattered vascular bundles.
• Xylem: (Inside) water and mineral transport (root to shoot).
• Phloem: (Outside) sugar transport (source to sink).
• Ground Tissue:
  • Outermost layer of ground tissue: Cortex.
• Parenchyma: Ground tissue cells.

Plant Cells (Vascular Tissue)

• Xylem cells: Dead at maturity. Found in all vascular plants.
  • Tracheids: Basic water-transport cells.
  • Vessels: More efficient water-transport cells.
• Phloem cells: Alive at maturity.
  • Sieve cells: The "transport tubes" of phloem.
  • Companion cells: Support sieve cells.

Plant Processes and Functions

• Guard Cells: Regulate stomata opening/closing (water levels).
• Root Hairs: Increase surface area for water absorption.
• Cork: Provides structure, strength, and support (Programmed cell death).
• Wood: Transfers xylem and phloem.
• Wood Rays: Allow lateral movement of water/sap.
• Meristems (Stem Cells): Cells with rapid growth potential.
  • Apical Meristems: Located at the tips of roots and shoots, involved in primary growth.
  • Lateral Meristems: Responsible for secondary growth.
• Secondary Growth: Growth in girth of woody plants through the vascular cambium to form secondary xylem and phloem.

Explore the fascinating characteristics of plants and their closest relatives, green algae. This quiz delves into similarities in cell walls, energy storage, and photosynthesis, as well as the defining features of non-vascular plants. Test your knowledge on how these organisms interrelate and function in their environments.