Plant & Animal Tissues – Quick Review

Plant Cells

  • Multicellular, eukaryotic; contain nucleus & membrane-bound organelles.
  • Unique organelles:
    • Cell wall ➜ shape, support, protection.
    • Chloroplast ➜ photosynthesis.
    • Large central vacuole ➜ storage, maintains turgor.

Plant Structural Systems

  • Shoot system ➜ leaves, stems, flowers, fruits (above ground).
  • Root system ➜ roots, tubers (below ground).

Plant Tissues

Dermal Tissue (Epidermis)

  • Outer single layer; covered by cuticle (reduces water loss, blocks pathogens).
  • Root hairs ➜ increase absorption area.
  • Trichomes on stems ➜ shade, conserve water.
  • Guard cells & stomata on leaves ➜ gas exchange.

Ground Tissue

  • Parenchyma ➜ thin-walled, large vacuoles; storage, photosynthesis, gas diffusion.
  • Collenchyma ➜ uneven thick walls; flexible support for growing parts.
  • Sclerenchyma ➜ lignified, dead at maturity; rigid support (fibres & sclereids).

Vascular Tissue

  • Xylem ➜ transports water & minerals root→shoot; tracheids & vessel elements (dead, hollow).
  • Phloem ➜ transports sucrose & organics; sieve-tube elements (living, no nucleus).

Animal Tissues

Epithelial Tissue

  • Continuous sheets lining surfaces & cavities; functions: secretion, absorption, protection, filtration.
  • Simple epithelium (one layer):
    • Squamous ➜ thin; blood vessels, alveoli.
    • Cuboidal ➜ box-shaped; kidney tubules.
    • Columnar ➜ tall; digestive tract, oviducts (with microvilli/cilia).
  • Stratified epithelium ➜ multiple layers; skin, mouth, vagina.
  • Glandular epithelium ➜ secretion; unicellular (goblet cell) or multicellular glands.

Connective Tissue

  • Most abundant; components: specialized cells, protein fibers, ground substance (ECM).
  • Loose (areolar) ➜ elastic support; around organs, allows expansion.
  • Dense ➜ packed collagen; tendons & ligaments.
  • Reticular ➜ mesh support in lymphoid organs & red marrow.
  • Cartilage ➜ chondrocytes in lacunae; hyaline, elastic, fibrocartilage.
  • Bone ➜ osteoblasts (form), osteocytes (maintain), osteoclasts (resorb).
  • Blood ➜ plasma + erythrocytes, leukocytes, platelets (formed in marrow).
  • Adipose ➜ adipocytes store lipids; white fat (adults), brown fat (infants, heat production).

Nervous Tissue

  • Neurons: dendrites (input), cell body, axon (output).
  • Neuroglia: support, protect, nourish neurons.

Muscular Tissue

  • Skeletal ➜ striated, multinucleate; voluntary movement.
  • Smooth ➜ spindle-shaped, non-striated; involuntary (viscera, vessels).
  • Cardiac ➜ striated, branched; involuntary contraction of heart.

Plant vs Animal Cell / Tissue Highlights

  • Plants: cell wall, chloroplasts, large vacuole; tissues organized into dermal, ground, vascular.
  • Animals: lack cell wall/chloroplast; tissues grouped into epithelial, connective, nervous, muscular.
  • Transport: xylem & phloem (plants) vs circulatory system with blood (animals).
  • Support: lignified sclerenchyma & cell walls (plants) vs bone & cartilage (animals).