Biology Chapter 3 Vocabulary Study Guide

A comprehensive vocabulary study guide for biology, focusing on essential biological terms and definitions.

Cell

The simplest unit of life, consisting of one or more living units.

Cell membrane

Separates the living material within the cell from the nonliving environment around it.

Nucleus

The part of the cell that houses all of its DNA.

Cytoplasm

The entire contents of the cell enclosed by the cell membrane but outside the nucleus.

Prokaryotes

Organisms that lack a nucleus, such as bacteria and archaea.

Eukaryotes

Organisms that have a nucleus, including animals, plants, fungi, and protists.

DNA

A polymer of nucleotides that stores genetic information.

RNA

A molecule complementary to DNA that functions in protein synthesis.

Proteins

Molecules that provide structure and perform most cellular work.

Transcription

The process of synthesizing RNA from DNA.

Translation

The process of synthesizing proteins from an RNA template.

ATP

An energy-carrying molecule composed of adenine, ribose, and phosphate groups.

Selectively permeable

Describes a membrane that allows some substances to pass while restricting others.

Diffusion

The movement of molecules from an area of high concentration to an area of low concentration.

Passive transport

The movement of substances across membranes without the use of energy.

Active transport

The movement of substances against a gradient, requiring energy.

Phototroph

An organism that captures energy from sunlight.

Chemotroph

An organism that derives energy from chemicals.

Autotroph

An organism that produces its own food.

Heterotroph

An organism that obtains food from other organisms.

Chemoautotroph

An organism that uses inorganic chemicals for energy and makes its own food.

Chemoheterotroph

An organism that gets energy and carbon from other organisms.

Metabolism

All chemical reactions occurring within an organism.

Catabolism

The breakdown of molecules, producing ATP.

Anabolism

The building of molecules, which requires energy.

Endotherms

Organisms that generate body heat internally.

Ectotherms

Organisms that rely on environmental heat.

Homeostasis

The maintenance of stable internal conditions.

Stimulus

A change in the environment that elicits a response.

Response

The reaction of an organism to a stimulus.

Endocrine system

The system that secretes hormones into the bloodstream.

Hormone

A chemical messenger transported in the blood.

Negative feedback

A response that counteracts a change.

Positive feedback

A response that enhances a change.

Gas exchange

The exchange of oxygen and carbon dioxide.

Blood

The fluid in closed circulatory systems.

Gills

Organs for gas exchange in aquatic organisms.

Lungs

Organs for breathing air.

Capillaries

Small blood vessels where exchange of substances occurs.

Osmosis

The movement of water across membranes.

Osmoregulation

The control of water balance in organisms.

Nitrogenous waste

Waste produced from the metabolism of proteins.

Ammonia

A toxic form of nitrogen waste.

Urea

A less toxic form of nitrogen waste.

Uric acid

The least toxic nitrogen waste.

Innate immunity

The non-specific defense system of an organism.

Adaptive immunity

The specific immune response tailored to particular pathogens.

Antigen

A molecule that triggers an immune response.

Asexual reproduction

Reproduction involving one parent.

Sexual reproduction

Reproduction involving two parents.

Fertilization

The fusion of gametes to form a zygote.