Tissues Plant And Animal Tissues Chapter Notes | Biology for SSS 1 PDF Download

Tissues: The Teams of Workers

• A tissue is a group of similar cells that perform a specific function.
• Plants and animals have tissue systems to carry out essential tasks.
• Example: In humans, epithelial tissue covers the skin, and muscle tissue enables movement.
• Example: In plants, conducting tissue transports water and food.
• Tissues combine to form organs (e.g., tongue with epithelial, nerve, and muscle cells).
• Organs work together in organ systems (e.g., digestive system).
• Organ systems collectively form an organism (e.g., plant with root and shoot systems).

Plant Tissues

• Plant tissues are divided into two main types: Meristematic and Permanent.

Meristematic Tissue

• Cells can divide to produce new cells.
• Located at growing points like tips of roots, stems, and branches.
• Found between bark and wood in trees, increasing stem diameter.
• Characteristics:
  • Cells are small and usually cubical.
  • Cell walls are thin.
  • Nuclei are large.
  • Vacuoles are nearly absent.
  • Cells are tightly packed with minimal intercellular spaces.
  • Cells actively divide, adding new cells.
  • New cells transform into permanent tissues.
• Types of Meristematic Tissue:
  • Apical Meristem: Found at tips of roots, stems, young leaves, and axillary buds.
  • Cambium (Lateral Meristem): Located below bark, responsible for stem diameter growth.

Permanent Tissues

• Cells cannot divide and have specific shapes and functions.
• May be living (with nucleus) or dead (without nucleus).
• Types: Protective, Supporting, and Conducting.

Protective Tissue

• Cells have thick walls.
• Located on the surface of roots, stems, and leaves.
• Examples:
  • Epidermis of leaves secretes waxy, waterproof material.
  • Cork cells in bark contain strong waterproof material.

Supporting Tissue

• Provides structural support to plants.
• Types: Parenchyma, Collenchyma, and Sclerenchyma.
• Parenchyma:
  • Cells are large, thin-walled, and oval, circular, or polygonal.
  • Usually have a single large vacuole.
  • Found in soft parts like cortex and pith.
  • May store food (e.g., starch in potatoes).
  • Provides temporary support.
  • Chlorenchyma: Parenchyma with chloroplasts in leaves, aids in photosynthesis.
• Collenchyma:
  • Cells are elongated with thickened corners.
  • Found in leaf stalks and below stem epidermis.
  • Provides support to plant parts.
• Sclerenchyma:
  • Consists of long, narrow, dead cells with thick, lignified walls.
  • Provides strength to stems and leaf veins.
  • Examples: Fibres (used in ropes, mats, textiles like linen and hemp) and stone cells (in walnut shells, gritty masses in pears).
• Parenchyma, Collenchyma, and Sclerenchyma are simple tissues (made of one cell type).

Conducting Tissue (Vascular Tissue)

• Transports water, minerals, and food in plants.
• Types: Xylem and Phloem (complex tissues with multiple cell types).
• Xylem:
  • Cells are elongated, thick-walled, and tubular.
  • Transports water and minerals upward from roots.
  • Older xylem forms wood and does not transport.
  • Annual rings (xylem layers) indicate a tree’s age.
  • Components:
    • Tracheids: Elongated, dead cells with lignified walls, forming tubes for support and transport.
    • Vessels (Tracheae): Long, tube-like structures with dissolved transverse walls for water transport.
    • Xylem Parenchyma: Living cells for food storage and water conduction.
• Phloem:
  • Transports food from leaves to other parts (downward) and to growing leaves (upward).
  • Components:
    • Sieve Tubes: Elongated cells with perforated transverse walls (sieve plates) for food transport.
    • Companion Cells: Living cells aiding sieve tube function.
    • Phloem Parenchyma: Stores starch, fat, and organic material.
    • Phloem Fibres: Sclerenchymatous cells for support.
• Xylem and Phloem form vascular bundles (e.g., leaf veins), connecting with stem and root tissues.

Animal Tissues

Epithelial, Connective, Muscular, and Neural.

Epithelial Tissue

• Forms a thin, protective layer of tightly packed cells with no intercellular spaces.
• Location: Covers body surface, lines cavities, and internal organs (e.g., skin, mouth, lungs, stomach, blood vessels).
• Cell Shapes: Flat, cuboidal, or columnar.
• Functions: Protection, absorption, secretion, sensory perception.
• Types:
  • Squamous Epithelium: Thin, flat cells with prominent nuclei; found in mouth, nasal cavities, blood, and lymph vessels; protects against injury, germs, and drying.
  • Stratified Epithelium: Multiple layers of cells; found in skin and cornea.
  • Cuboidal Epithelium: Cube-shaped cells; found in kidney tubules, salivary glands, pancreatic ducts.
  • Columnar Epithelium: Tall, cylindrical cells; found in stomach and intestine lining.
  • Ciliated Columnar Epithelium: Columnar cells with cilia; found in trachea; cilia move materials.
  • Glandular Epithelium: Secretes chemicals; found in stomach, intestine, sweat glands, tear glands, liver.

Connective Tissue

• Binds tissues and organs, keeping them in place.
• Characteristics: Abundant matrix, fewer cells, and fibres.
• Types: Connective Tissue Proper, Supportive Connective Tissue, Fluid Connective Tissue.
• Connective Tissue Proper:
  • Areolar Tissue: Found beneath skin epidermis; makes skin elastic and withstands pulling.
  • Adipose Tissue: Stores fat; forms padding under skin, around kidneys, and eyeballs; insulates body heat.
  • Fibrous Connective Tissue: Forms tendons (muscle to bone) and ligaments (bone to bone).
• Supportive Connective Tissue:
  • Cartilage: Non-porous, elastic, no blood vessels or nerves; found in nose tip, ears, trachea, vertebrae, and bone ends.
  • Bone: Hard, porous, with blood vessels and nerves; contains osteoblasts and inorganic salts.
• Fluid Connective Tissue:
  • Blood: Composed of plasma (liquid) and cells (red blood cells, white blood cells, platelets); transports nutrients and provides immunity.
  • Lymph: Plasma-like fluid with white blood cells, no red blood cells; aids in transport and immunity.

Muscle Tissue

• Forms muscles that contract and relax for movement.
• Types:
  • Striated (Voluntary) Muscles: Controlled by will; long, nucleated, striated fibres; found in arms, legs, face, neck; constitute 50% of body weight.
  • Unstriated (Involuntary) Muscles: Not controlled by will; spindle-shaped, uninucleated cells; found in intestine walls, iris, skin, blood vessels, urinary bladder, uterus.
  • Cardiac Muscles: Involuntary, striated, branched, uninucleated; found in heart walls; contract without stimulation and resist fatigue.

Neural Tissue

• Forms the nervous system with specialized neurons.
• Neuron Structure: Contains cell body (perikaryon with nucleus), dendrites (hair-like extensions), and axon (long extension, up to 3 meters).
• Axons bundle to form nerves.
• Function: Perception and response in animals.

Analogies

• Blood Vessels - Rivers: Transport materials like rivers carry water.
• Capillaries - Canals: Small channels for material exchange.
• Red Blood Cells - Ships: Carry oxygen like ships transport goods.
• White Blood Cells - Anti-terrorist Squad: Fight infections like a squad fights threats.
• Urinary System - Drainage: Removes waste like a drainage system.
• Kidneys - Aquaguards: Filter blood like water purifiers.
• Liver - Thrifty Housekeeper: Manages and stores nutrients efficiently.
• Nerves - Landlines: Transmit signals like telephone lines.
• Plant Leaves - Agriculture Farms: Produce food through photosynthesis.