The study of the living world.
Modern biology encompasses all levels of organization and interaction:
• among organic molecules
• among organelles within a cell
• among cells in an organ
• among the organ systems in an organism
• between organisms and the abiotic environment
• among individuals in a population
• among species in a biological community
Knowing the facts of biology without an understanding of the relationships among these levels of organization is insufficient to understand the biological world.
How do I know that you are alive?
Life is defined in terms of qualities that the living uniquely share:
• Life is organized o in sequences of increasing complexity (structures within structures) o the basic unit of life is the cell o levels of biological organization are hierarchical from cells - organisms - communities - biosphere
• Life requires energy o the natural tendency of matter is towards disorder (i.e., entropy or randomness) o living systems acquire and use energy to maintain their highly organized state o metabolism: the biochemical reactions that acquire and use energy
• Living things must maintain an internal constancy o this requires a separation from the non-living world o for metabolic processes to function normally, living things need to keep themselves stable in temperature, moisture level, chemistry, etc. o homeostasis: the ability to maintain internal constancy (i.e., to stay the same)
• Living things grow, develop, and reproduce o vital if a population of organisms is to survive more than one generation> o "Instructions" for growth and development are encoded in genes
• Living things react to environmental change - Irritibility - (an individual reacts to its environment) o reaction may be immediate as in a reaction to extreme heat, or longer term as in a change in leaf color in response to day length, but certainly within the lifetime of the