Key Concepts in Biology

Characteristics of Life

  • Growth & Development

    • Organisms grow and develop throughout their life.
    • Differentiation: As the organism grows, its parts become different, specializing for various functions.

  • Reproduction

    • Sexual Reproduction: Involves two parents, leading to offspring that are genetically unique (e.g., humans).
    • Asexual Reproduction: Involves one parent, resulting in clones of the parent (e.g., bacteria).

  • Evolution

    • Over time, species change through evolution, adapting to their environment and passing on traits to future generations.

  • Cellular Structure

    • Unicellular Organisms: Composed of a single cell (e.g., bacteria).
    • Multicellular Organisms: Composed of multiple cells, working together (e.g., humans).
    • Prokaryotic Cells: Lack a nucleus (e.g., bacteria).
    • Eukaryotic Cells: Have a nucleus (e.g., animal cells).

  • Homeostasis

    • The ability of an organism to maintain a stable internal environment (e.g., humans maintaining body temperature at 98.7extoF98.7^{ ext{o}}F).

  • Obtaining and Using Energy

    • Autotrophs: Organisms that can make their own food (e.g., plants via photosynthesis).
    • Heterotrophs: Organisms that consume other organisms for energy (e.g., humans).

  • Genetic Information

    • All living organisms contain genetic material (DNA or RNA) that contains instructions for growth, development, and functioning.

  • Response to Stimuli

    • Organisms respond to external stimuli (e.g., feeling a slap and responding by slapping back or dodging).

This framework outlines the fundamental processes and characteristics that define life and underscores the complexity of biological systems.