Lecture 2: Properties of Life, Levels of Biological Organization, & The Scientific Method

A set of vocabulary flashcards covering key concepts from the lecture notes on life, organization, and the scientific method.

Biology

The science that studies life and living organisms.

Organism

A living thing; typically composed of cells and capable of growth, reproduction, response to stimuli, energy use, and evolution.

Cell

The basic unit of all living things; the smallest form of life, often enclosed by a plasma membrane.

Plasma membrane

The boundary that separates a cell from its surroundings and helps keep its contents organized.

Homeostasis

Maintenance of a relatively constant internal environment through internal regulation and behavior.

Stimulus

An internal or external signal that elicits a response; examples include low blood sugar or smelling food.

Photosynthesis

The process by which plants convert light energy into chemical energy.

Metabolism

The set of chemical processes by which organisms acquire and use materials and energy.

Growth

Increase in size or number of cells; for single-celled organisms, growth by size; for multicellular organisms, growth mainly by cell division.

Reproduction

The process by which organisms produce offspring (by division, seeds, or birth).

DNA

Deoxyribonucleic acid; genetic material present in cells and passed to descendants.

Gene

A specific segment of DNA that is the basic unit of heredity.

Evolution

Descent with modification; organisms adapt and change over time.

Extinction

The permanent disappearance of a species when it no longer exists.

Nonliving

Things that do not meet all characteristics of life; not composed of cells.

Atoms

The basic units of matter that define elements.

Molecules

Groups of two or more atoms bonded together.

Population

A group of individuals of the same species living in a particular area.

Species

A group of organisms that can interbreed and produce fertile offspring.

Community

All populations of different species living together in a given area.

Ecosystem

A system consisting of living organisms and their physical environment interacting in a specific area.

Scientific method

A six-step approach to solving problems: observation, question, hypothesis, prediction, experiment, conclusion.

Observation

Careful noticing of a phenomenon or event that leads to questions.

Hypothesis

A proposed explanation addressing the observation or question.

Prediction

A statement of expected outcomes if the hypothesis is correct (If… then…).

Experiment

A test designed to evaluate the prediction under controlled conditions.

Conclusion

A judgment based on repeatable results and data.