Biology: Science, Evolution, and Taxonomy Concepts (Modules 1–3)

A comprehensive set of vocabulary flashcards covering the key concepts from science, the scientific method, life’s characteristics, biological organization, repeatability and sampling, basics of evolution, and taxonomy/phylogeny.

Limitations of science

Science cannot answer moral, ethical, or supernatural questions and cannot prove absolute certainty; it builds best explanations from available evidence.

Scope of science

Science asks questions about the natural world and uses evidence and repeatable experiments to explain phenomena.

Moral and ethical questions (outside science)

Questions about values or meanings that science is not equipped to answer.

Absolute certainty in science

Science does not prove things with absolute certainty; explanations are based on evidence and may be revised.

Testable question

A question that can be tested, measured, or observed in the natural world.

Observation

Noticing and recording phenomena using the senses or instruments.

Question

The inquiry you are trying to figure out in a study.

Independent Variable

The factor deliberately changed by the experimenter to test its effect.

Dependent Variable

The factor measured to assess the effect of the independent variable.

Hypothesis

A testable statement, often written as 'If… then… because…'..

Experiment

A controlled test designed to test a hypothesis by manipulating variables.

Data Collection

Gathering observations and measurements from experiments.

Analysis

Interpreting results to determine what the data show.

Conclusion

Judgment about whether the data support the hypothesis.

Control

A standard for comparison where the tested variable is left unchanged.

Theory (scientific)

A well-supported, broad explanation of natural phenomena (not a guess).

Made of cells

Living things are composed of one or more cells—the basic unit of life.

Use and obtain energy

Organisms acquire energy and use it to power metabolic processes.

Reproduce

The ability to produce offspring.

Grow and develop

Increase in size and progression through life stages.

Respond to environment

Ability to sense and react to stimuli from the surroundings.

Maintain homeostasis

Regulation of internal conditions to remain stable.

Have genetic material (DNA)

Organisms contain DNA as their hereditary material.

Evolve as a group over time

Populations change genetically across generations.

Atom

The basic unit of matter; building block of elements.

Molecule

A chemical structure made of two or more atoms bonded together.

Cell

The basic unit of life; the fundamental unit of biology.

Tissue

A group of similar cells performing a specific function.

Organ

A structure composed of tissues that performs a particular function.

Organ System

A group of organs that work together to perform a broader function.

Organism

An individual living thing.

Population

A group of individuals of the same species in a region.

Community

All populations of different species living in a region.

Ecosystem

The living and nonliving components in an area interacting as a system.

Biosphere

The global sum of all ecosystems; the zone of life on Earth.

Repeatability

Experiments should be repeatable by others with similar results.

Sample Size

Number of experimental units; larger samples yield more reliable results.

Observational Investigation

Observations where variables are not manipulated.

Experimental Investigation

Studies that manipulate variables and use controls to test hypotheses.

Biological Evolution

Change in the genetic makeup of populations over time; explains diversity and shared traits.

Natural Selection

Mechanism by which traits that improve survival or reproduction become more common over generations.

Variation

Differences among individuals in a population.

Heritability

Traits that are genetically passed from parents to offspring.

Differential Reproductive Success

Some individuals reproduce more successfully, shifting trait frequencies.

Environmental Pressures

Factors such as predators, climate, food, disease, or human activity that influence evolution.

Relative Fitness

The reproductive success of an individual relative to others in the population.

Reproductive Output

The number of offspring produced by an individual; drives adaptive change.

MRCA (Most Recent Common Ancestor)

The last shared ancestor between two or more organisms.

Cladistics

A method of building phylogenetic trees based on shared derived traits.

Shared Derived Traits

Traits that evolved after divergence from a common ancestor.

Ancestral Traits

Traits present in a common ancestor.

Derived Traits

Traits that evolved after divergence from an ancestor.

Clades

Groups that include an ancestor and all its descendants.

Homologous Structures

Inherited from a common ancestor; show shared ancestry.

Analogous Structures

Structures with similar function but different origins; due to convergent evolution.

Tree of Life

A single framework showing the evolutionary history of all life on Earth.

Phylogenetic Tree

A diagram showing evolutionary relationships among species.

Pedigree

A family tree used to study inheritance patterns.

Taxonomy

The science of classifying organisms into hierarchical groups based on shared characteristics.

Phylogeny

The study of evolutionary relationships among organisms.

Domain

Highest taxonomic rank in the three-domain system (Bacteria, Archaea, Eukarya).

Kingdom

Second-highest taxonomic rank after domain in traditional hierarchy.

Phylum

Taxonomic rank below kingdom; groups organisms with related characteristics.

Class

Taxonomic rank below phylum; groups related orders.

Order

Taxonomic rank below class; groups related families.

Family

Taxonomic rank below order; groups related genera.

Genus

Taxonomic rank above species; a group of related species.

Species

Basic unit of classification; organisms capable of interbreeding and producing fertile offspring.

Three-Domain System

Classification into Bacteria, Archaea, and Eukarya based on genetic differences.

Bacteria

Prokaryotic, unicellular organisms.

Archaea

Prokaryotic, genetically distinct from Bacteria; often in extreme environments.

Eukarya

Organisms with complex cells; includes animals, plants, fungi, and protists.