Biology Form 4 - Condensed Notes

Fields and Careers in Biology

  • Biology: Study of living things.

  • Branches: Microbiology, Botany, Physiology, Genetics, Ecology.

  • Applications: Medicine, food production, pharmaceuticals, agriculture.

  • Careers: Biotechnology, food technology, environmental engineering, health, agriculture, forestry.

Safety and Rules in a Biology Laboratory

  • Emergency equipment: Shower, eyewash station.

  • Equipment: Fume hood, laminar flow cabinet, biological safety cabinet.

  • Personal Protective Equipment: Goggles, gloves, face mask, lab coat, lab shoes.

  • Waste disposal: Specific guidelines for disposing of chemicals and biological waste.

  • Spill management: Procedures for handling chemical and mercury spills.

  • Safety Practices: Clothing ethics, emergency help, handling specimens, fire safety, chemicals, glass.

Communicating in Biology

  • Data presentation: Tables for organizing data.

  • Graphs: Line graphs, bar charts, histograms.

  • Biological drawings: Accurate, labeled, proportionate.

  • Anatomical terms: Plane, section, direction.

Cell Structure and Function

  • Cell Theory: All living things are made of cells.

  • Plant vs. Animal Cells: Differences in shape, organelles.

  • Organelles:

    • Mitochondria: Energy production (ATP).

    • Centrioles: Cell division (animal cells).

    • Golgi Apparatus: Modifies and packages proteins.

    • Plasma Membrane: Controls substance movement.

    • Lysosome: Breaks down cell waste.

    • Nucleus: Controls cell activities (DNA).

    • Ribosome: Protein synthesis.

    • Endoplasmic Reticulum: Transport system.

    • Vacuole: Storage (large in plant cells).

    • Chloroplast: Photosynthesis (plant cells).

    • Cell Wall: Support (plant cells).

  • Unicellular Organisms: Single cell performs all life processes.
    * Movement: Amoeba (pseudopodia), Paramecium (cilia).
    * Nutrition: Phagocytosis, cilia.
    * Excretion: Diffusion, contractile vacuole (osmoregulation).
    * Reproduction: Binary fission, spore formation, conjugation.

  • Multicellular Organisms: Specialized cells for specific functions.
    * Human Cells: Muscle, nerve, blood, epithelial, sperm.
    * Plant Cells: Xylem, phloem, mesophyll, guard, root hair.

  • Tissues: Groups of similar cells.
    * Human: Epithelial, muscle, nerve, connective.
    * Plant: Meristematic, permanent (dermal, ground, vascular).

  • Cell Component Density: High density of certain components correlate with specialized functions.

  • Cell Dysfunction: Can lead to diseases (e.g., Tay-Sachs).

Levels of Organization in Multicellular Organisms

  • Cells → Tissues → Organs → Organ Systems → Organism.

  • Human Organ Systems: Reproductive, respiratory, digestive, circulatory, lymphatic, nervous, integumentary, endocrine, skeletal, muscular, urinary.

  • Plant Systems: Shoot and root systems.

Movement of Substances Across the Plasma Membrane

  • Plasma Membrane: Controls movement of substances.

    • Structure: Phospholipid bilayer, proteins, glycoproteins, glycolipids, cholesterol.

  • Permeability: Selective permeability based on molecule size, polarity, and ionic charge.

  • Passive Transport: No energy required.

    • Simple Diffusion: Movement down concentration gradient.

    • Osmosis: Water movement from high to low water potential.

    • Facilitated Diffusion: Using channel or carrier proteins.

  • Active Transport: Energy required, movement against the concentration gradient through carrier proteins (pumps) such as sodium-potassium pump and proton pump.

  • Solutions: Isotonic, hypotonic, hypertonic effects on cells.

  • Applications: Wilting, rehydration drinks, saline solutions, liposomes, reverse osmosis.

Chemical Compositions in a Cell

  • Water: Polar molecule, cohesive and adhesive forces, high specific heat capacity.

  • Carbohydrates: Organic compounds (C, H, O).
    * Types: Monosaccharides, disaccharides, polysaccharides.
    * Functions: energy source, food reserve, support structure.

  • Proteins: Complex compounds (C, H, O, N).
    * Made of amino acids.
    * Functions: building new tissues, repair damaged tissue, synthesis of enzymes, hormones, antibodies

  • Lipids: Hydrophobic compounds (C, H, O).
    * Types: Fats, waxes, phospholipids, steroids.
    * Functions: Cuticle, sebum, plasma, membrane, energy.

  • Nucleic Acids: Polymers of nucleotides (C, H, O, N, P).
    * Types: DNA, RNA. Provide genetic codes in living organisms
    * Structure of DNA: Double helix of nucleotide.