Living Things: Characteristics, Needs, Classification, and Evolution

Comprehensive vocabulary flashcards covering the characteristics and needs of living things, experimental disproof of spontaneous generation, levels of biological classification, binomial nomenclature, and evolutionary principles.

Organism

Any living thing, such as an animal, a plant, a mushroom, strep bacteria, or a lichen.

Cell

The basic unit of structure and function in living things.

Unicellular Organism

A single-celled organism in which one cell carries out all the functions necessary to stay alive.

Multicellular Organism

An organism composed of many cells that are specialized to perform specific tasks and work together to keep the organism alive.

Carbohydrates

Energy-rich chemicals that provide cells with energy.

Proteins and Lipids

Chemicals used as building blocks for cells and tissues, with lipids also functioning to give and store energy.

Nucleic Acids

Chemicals, such as deoxyribonucleic acid (DNA), that contain genetic information and provide chemical instructions directing the actions of cells.

Stimulus

Any change or signal in an organism's environment (such as light, sound, flavor, or odor) that causes it to react in some way.

Response

An action or change in behavior displayed by an organism in reaction to a stimulus.

Asexual Reproduction

A reproductive process involving only one parent that produces offspring identical to that parent, such as budding in a hydra.

Sexual Reproduction

A reproductive process in which two parents combine their DNA to produce an offspring with a mix of characteristics from both parents.

Spontaneous Generation

The mistaken historical belief that living things can arise from nonliving sources, such as maggots emerging directly from rotting meat.

Controlled Experiment

A scientific test in which two or more tests are carried out that are identical in every way except for one variable.

Control Group

The group in an experiment exposed to the exact same factors as the experimental group, except that it is not exposed to the specific variable being tested.

Francesco Redi

An Italian doctor in the 1600s who conducted a controlled experiment with covered and uncovered jars of decaying meat to demonstrate that flies laid eggs that hatched into maggots, helping disprove spontaneous generation.

Louis Pasteur

A French chemist who disproved spontaneous generation by using curved-neck flasks of boiled broth to demonstrate that bacteria entered from the air and did not arise spontaneously from the broth.

Autotroph

An organism (also called a producer) that makes its own food by capturing the sun's energy through photosynthesis to convert water and gas into food.

Heterotroph

An organism (also called a consumer) that cannot make its own food and must feed on other organisms or break down dead organisms to obtain energy.

Homeostasis

The maintenance of stable internal conditions inside an organism despite changes in the external environment.

Classification

The scientific process of grouping organisms and objects based on their shared similarities and characteristics.

Taxonomy

The scientific study of how organisms are classified, named, and identified.

Domain

The broadest level of organization in biological classification, consisting of Eukarya, Archaea, and Bacteria.

Domain Eukarya

The classification domain comprising eukaryotic organisms whose cells contain nuclei with DNA, including the kingdoms of plants, animals, fungi, and protists.

Domain Archaea

A classification domain of unicellular organisms that lack a nucleus and have cellular structures and chemical processes distinct from bacteria.

Domain Bacteria

A classification domain consisting of unicellular organisms that lack a nucleus and differ from Archaea in cellular structure and chemical processes.

Levels of Classification

The eight-tier taxonomic hierarchy arranged from broadest to most specific: Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species.

Carolus Linnaeus

A Swedish biologist in the 1730s who developed a system of classifying organisms based on observable traits and introduced binomial nomenclature.

Binomial Nomenclature

A two-part naming system in which an organism is assigned a unique scientific name consisting of its genus and species, written in italics with only the genus capitalized.

Genus

A classification grouping of similar, closely related organisms; it forms the first, capitalized word in an organism's scientific name.

Species

A group of similar organisms that can mate with each other and produce fertile offspring; it forms the second word in an organism's scientific name.

Taxonomic Key

A guide consisting of a series of paired, numbered statements describing physical characteristics used to identify and name unknown organisms.

Evolution

The process of change over time by which modern species developed from earlier kinds of life.

Natural Selection

The evolutionary mechanism proposed by Charles Darwin stating that individuals better adapted to their environment are more likely to survive and reproduce.

Convergent Evolution

The evolutionary process by which unrelated organisms independently evolve similar characteristics due to living in similar environments.

Aristotle's Classification System

An early classification system created by Greek scholar Aristotle (384 to 322 BCE) dividing animals by how they move (fly: $22\%$, walk/run/hop: $46\%$, swim) and plants by size (grass, shrubs, trees).