8/27 Scientific Method and Core Biological Theories

Vocabulary flashcards covering the key terms from the lecture on the hypothetical deductive method, variables, hypotheses, theory versus construct versus fact, and major biological theories.

Hypothetical deductive method

A scientific approach where observations raise questions, a hypothesis is formed, and experiments test the hypothesis to explain patterns and processes in nature.

Observation

Noticing a phenomenon in the environment or within organisms that prompts further questions and investigation.

Question

The inquiry that follows an observation, such as asking what, why, or how a phenomenon occurs.

Independent variable

The factor deliberately manipulated or varied in an experiment; represented on the x axis in graphs.

Dependent variable

The outcome measured in an experiment that changes in response to the independent variable; represented on the y axis in graphs.

Hypothesis

A testable statement that explains an observation and can be evaluated through experimentation.

Null hypothesis (H0)

The hypothesis that posits no relationship between the independent and dependent variables.

Alternative hypothesis (HA)

The hypothesis that posits a relationship or effect between the dependent and independent variables.

Experimentation

The process of testing a hypothesis by manipulating the independent variable and observing the dependent variable in lab or field settings.

Theory

A well tested, unifying explanation for a broad range of observations that coordinates facts and laws, with revisions possible as new evidence emerges.

Construct

An untestable statement used to explain observations, often contrasted with hypotheses and theories.

Fact

An observation or conclusion considered true to a high degree, but not an absolute; facts require mechanisms and may be revised with new evidence.

Empirical evidence

Quantifiable and measurable data derived from observation or experimentation that support or refute hypotheses.

Cell theory

The idea that the cell is the smallest unit of life and that all organisms are composed of cells carrying out life processes.

Germ theory

The idea that specific microorganisms, such as bacteria and fungi, can cause disease.

Evolutionary theory

The concept that life changes over time through evolutionary mechanisms, with descent from common ancestors modified over generations.

Descent with modification

Darwin's idea that modern species arise from common ancestors through gradual changes over time.

Gene theory

The concept that genes are the units of inheritance and that DNA carries genetic information.

DNA

The molecule of inheritance discovered in 1954; a four nucleotide alphabet that encodes genetic information.

Genetic alphabet

The four nucleotide bases—A, C, G, and T—that form the code for DNA sequences.