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Characteristics of Life

• Metabolism: Refers to all chemical reactions occurring within organisms, encompassing energy production and utilization.

• Growth and Development: Involves an increase in size and complexity over time.

• Reproduction: The process of producing new individuals, ensuring species continuity.

• Homeostasis: The ability of an organism to maintain a stable internal environment despite external changes.

• Response to Stimuli: Describes how organisms react to changes in their surroundings.

• Adaptation: Evolutionary changes that enhance an organism's survival across generations.

• Organization: Refers to the structured arrangement of cells and systems within an organism.

Organisation of Life

• Chemical Level: Fundamental components such as atoms and molecules (e.g., water, proteins).

• Cellular Level: The basic unit of life, exemplified by cells (e.g., muscle cells).

• Tissue Level: Groups of similar cells working together (e.g., muscle tissue).

• Organ Level: Tissues that perform specific functions collectively (e.g., heart).

• Organ System Level: Multiple organs functioning together (e.g., circulatory system).

• Organism Level: A complete living being comprising various systems (e.g., humans).

Inorganic and Organic Differences

• Inorganic Compounds: Compounds that lack carbon-hydrogen bonds (e.g., water, minerals).

• Organic Compounds: Compounds that contain carbon-hydrogen bonds (such as carbohydrates, lipids, proteins, and nucleic acids).

Water

• Properties:

  • Polar Molecule: Exhibits uneven charge distribution, leading to polarity.

  • Universal Solvent: Capable of dissolving a variety of substances.

  • High Heat Capacity: Helps regulate temperature in organisms.

  • Cohesion and Adhesion: Contributes to surface tension and capillary action.

• Functions in Living Organisms:

  • Acts as a transport medium (e.g., blood plasma).

  • Serves as a medium for chemical reactions.

  • Assists in temperature regulation (e.g., through sweating).

  • Provides lubrication (e.g., in joints and eyes).

Minerals

• Essential for various biological functions:

  • Calcium (Ca): Vital for bone and teeth strength, as well as muscle function.

  • Iron (Fe): Key component of hemoglobin, facilitating oxygen transport.

  • Phosphorus (P): Critical for DNA, RNA, and energy molecules (ATP).

  • Magnesium (Mg): Acts as an enzyme activator and is a component of chlorophyll.

  • Potassium (K) and Sodium (Na): Involved in nerve impulses and muscle contraction.

pH Scale

• Definition: Measures the acidity or alkalinity of a substance.

• Scale Range: 0-14

  • 0-6: Acidic (high H⁺ concentration).

  • 7: Neutral (pure water).

  • 8-14: Alkaline/Basic (low H⁺ concentration).

• Biological Importance:

  • Enzyme activity is dependent on pH levels.

  • Blood pH (7.35-7.45) is crucial for maintaining bodily functions.

Carbohydrates

• Elements: Composed of Carbon (C), Hydrogen (H), and Oxygen (O).

• Types:

  • Monosaccharides: Single sugar molecules (e.g., glucose, fructose).

  • Disaccharides: Two monosaccharides linked together (e.g., sucrose, lactose).

  • Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen, cellulose).

• Functions:

  • Serve as a primary energy source.

  • Provide structural support (e.g., cellulose in plant cell walls).

Lipids

• Elements: Composed of Carbon (C), Hydrogen (H), and Oxygen (O).

• Types:

  • Fats and Oils: Function as energy storage.

  • Phospholipids: Essential for cell membrane structure.

  • Steroids: Includes hormones (e.g., cholesterol).

• Functions:

  • Long-term energy storage.

  • Provide insulation and protection.

  • Are integral components of cell membranes.

Proteins

• Elements: Composed of Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N).

• Building Blocks: Made up of amino acids.

• Types and Functions:

  • Structural Proteins: Provide support (e.g., collagen).

  • Enzymes: Catalyze and speed up chemical reactions.

  • Transport Proteins: Carry substances throughout the body (e.g., hemoglobin).

  • Hormones: Regulate various physiological processes (e.g., insulin).

  • Antibodies: Play a crucial role in the immune response.

Food Tests

• Test for Starch:

  • Reagent: Iodine solution.

  • Positive Result: Blue-black color.

• Test for Glucose:

  • Reagent: Benedict’s solution.

  • Positive Result: Brick-red precipitate (after heating).

• Test for Proteins:

  • Reagent: Biuret solution.

  • Positive Result: Purple color.

• Test for Lipids:

  • Reagent: Ethanol and water.

  • Positive Result: Milky-white emulsion.