Biology: Properties of Life, Levels of Organization, and Related Concepts

A set of vocabulary-style flashcards covering the core concepts from the notes, including life properties, levels of organization, taxonomy, evolution, domains, and related interdisciplinary topics.

Life (biology)

A characteristic of living systems defined by eight shared properties: order, sensitivity to stimuli, reproduction, adaptation, growth and development, regulation/homeostasis, energy processing, and evolution.

Order

Organisms are highly organized structures composed of one or more cells; inside cells, atoms form molecules and organelles.

Sensitivity to stimuli

Organisms respond to diverse stimuli, e.g., plants bending toward light or bacteria showing chemotaxis or phototaxis.

Reproduction

DNA is duplicated and passed to offspring; offspring belong to the same species and share traits.

Adaptation

A fit between organisms and their environment, arising from evolution by natural selection, enhancing reproductive potential.

Growth and development

Organisms grow and develop according to genetic instructions that guide cellular growth and developmental processes.

Regulation/Homeostasis

Maintenance of a relatively stable internal environment through regulatory mechanisms (e.g., thermoregulation, nutrient transport).

Energy processing

All organisms obtain and convert energy for metabolic activities; some use photosynthesis, others metabolize chemical energy.

Evolution

Diversity of life arises through mutations and natural selection acting on reproducing populations.

Atom

The smallest unit of matter that retains the properties of an element and forms the building blocks of molecules.

Molecule

Two or more atoms bonded together; many biologically important molecules are macromolecules.

Macromolecule

Large biological molecules formed by monomers, such as DNA, proteins, and polysaccharides.

DNA

Deoxyribonucleic acid; the genetic material containing instructions for an organism’s functioning.

Organelles

Membrane-bound subcellular structures within a cell that perform specialized functions.

Cell

The basic unit of life; all living things are cellular; viruses are not considered living because they are acellular.

Prokaryote

A single-celled organism lacking a nucleus and membrane-bound organelles.

Eukaryote

Organisms whose cells contain a nucleus and membrane-bound organelles.

Tissue

Groups of similar cells carrying out a common function.

Organ

A structure composed of multiple tissues functioning together for a specific task.

Organ system

A higher level of organization consisting of functionally related organs.

Organism

An individual living thing; can be single-celled or multicellular.

Microorganism

Organisms that are microscopic, including some bacteria, archaea, and single-celled eukaryotes.

Population

All individuals of a species living in a defined area.

Community

All populations (of different species) in a defined area.

Ecosystem

All living organisms in a defined area plus the abiotic components (air, water, nutrients) of that environment.

Biosphere

The highest level of organization, encompassing all ecosystems and life on Earth.

Taxonomy

The science of classifying organisms into hierarchical groups based on relatedness.

Binomial nomenclature

Two-part scientific naming system: genus name (capitalized) + species name (lowercase), italicized (e.g., Homo sapiens).

Genus

A group of closely related species.

Species

The basic unit of classification; organisms that can interbreed and produce fertile offspring.

Eight taxonomic levels

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

Domain

The highest taxonomic rank; three domains: Bacteria, Archaea, Eukarya.

Bacteria

Single-celled prokaryotes without a nucleus.

Archaea

Single-celled prokaryotes without a nucleus; many extremophiles.

Eukarya

Organisms with cells that contain nuclei and organelles; includes fungi, plants, animals, and protists.

Phylogenetic tree

A diagram showing evolutionary relationships among biological species based on similarities and differences in genetic or physical traits.

Node

Branch point on a phylogenetic tree representing a common ancestor and divergence.

Carl Woese

Microbiologist who proposed the three-domain system (Bacteria, Archaea, Eukarya) based on genetic relationships.

Forensic science

Application of science to answer questions related to law; includes analyzing biological materials and DNA.

Bioethics

Field addressing the ethical, legal, and social implications of biological research and practice; seeks to balance benefits with harms.