Biology Chapter 1: Characteristics of Life

Chapter 1: Characteristics of Life

• Biology is the branch of science that studies life.
• Organization is a defining feature of living organisms, consisting of many levels of organization starting with atoms and building up to cells, tissues, organs, organ systems, and finally the organism itself.
• Sensitivity is another defining characteristic of living organisms - they respond to stimuli in their environment.
• Growth is the increase in body size and is achieved by increasing the number and size of cells, as well as the amount of non-cellular material.
• Development includes all changes an organism undergoes throughout its life, specifically all changes from one stage to another in the life cycle.
• Reproduction is the process by which living organisms produce new individuals.
• Adaptation is a defining feature of living organisms, a characteristic that allows survival in a particular environment.
• Regulation is the ability of living organisms to maintain a stable internal environment (homeostasis) despite changes in the external environment.
• Energy processing describes how living organisms use energy for growth, movement, and all other life processes.
• Homeostasis is the maintenance of stable internal conditions despite external changes, achieved through various mechanisms such as thermoregulation (e.g., sweating).
• Metabolism refers to all chemical reactions that occur within a cell. These reactions can be categorized as either catabolic (breaking down molecules) or anabolic (building up molecules).
• Catabolism is the breakdown of complex molecules into simpler ones, releasing energy in the process.
• Anabolism is the building up of complex molecules from simpler ones, requiring energy input.
• Cells are the fundamental units of structure and function in living things.
• Prokaryotes are a group of single-celled organisms that lack a true nucleus.
• Eukaryotes are a group of organisms that do have a true nucleus.
• Tissues are made up of groups of similar cells that work together to perform a specific function.
• Organs are made up of different tissues working together to carry out a more complex function.
• Organ systems consist of multiple organs that work together to perform a particular bodily function.
• Organisms consist of multiple organ systems working together.
• Population is a group of individuals of the same species living in the same area.
• Community is a group of different populations living together in the same area.
• Ecosystem includes all living organisms (the biotic component) and their nonliving environment (the abiotic component), such as soil, water, and sunlight.
• Biosphere encompasses all ecosystems on Earth.
• Evolution is the source of the diversity of life, a process by which populations change over time, with adaptations aiding in survival.
• Species is a group of organisms that can interbreed and produce fertile offspring.
• Domain is a taxonomic classification that includes three domains: Eukarya, Bacteria, and Archaea.
• Eukarya includes multicellular organisms like plants, animals, and fungi, as well as single-celled protists.
• Bacteria and Archaea are both prokaryotes and represent single-celled organisms.
• Taxonomy is the branch of biology concerned with naming, identifying, and classifying organisms.
• Nomenclature is the system of assigning scientific names to organisms.
• Binomial nomenclature, introduced by Linnaeus, uses two words to name each species: the genus name (always capitalized) and the species name (not capitalized).
• Hierarchical classification is a system of classifying organisms in a series of increasingly inclusive categories.
• Taxonomic hierarchy includes these major levels: Domain, Kingdom, Phylum/Division, Class, Order, Family, Genus, Species.
• Species is the fundamental unit of classification.