Biology 20 Key Definitions

A set of vocabulary flashcards based on key definitions in Biology 20 including Ecosystems & Energy, Cycles, Photosynthesis, Cellular Respiration, and Human Systems.

Ecosystem

A community of organisms interacting with each other and with their physical environment.

Biosphere

All parts of Earth where living organisms exist.

Population

Members of the same species living in the same area.

Community

All the different populations living and interacting in an area.

Habitat

The place where an organism normally lives.

Producer

An organism that makes its own food, usually through photosynthesis.

Consumer

An organism that obtains energy by eating other organisms.

Decomposer

An organism that breaks down dead organisms and waste and returns nutrients to the environment.

Food chain

A sequence showing how energy passes from one organism to another.

Food web

A network of interconnected food chains.

Trophic level

A feeding level within an ecosystem.

Biodiversity

The variety of living organisms in an area.

Carrying capacity

The largest population an environment can sustainably support.

Limiting factor

Anything that restricts the growth or size of a population.

Symbiosis

A close relationship between organisms of different species.

Predation

An interaction where one organism hunts and eats another.

Competition

When organisms try to obtain the same limited resources.

Carbon cycle

The movement of carbon between organisms, the atmosphere, oceans, soil, and rocks.

Nitrogen cycle

The movement of nitrogen through the atmosphere, soil, and living organisms.

Water cycle

The continuous movement of water through Earth's atmosphere, land, and living organisms.

Photosynthesis

The process plants use to convert light energy into chemical energy stored in glucose.

Chloroplast

An organelle where photosynthesis occurs in plant cells.

Chlorophyll

A green pigment that absorbs light energy for photosynthesis.

Glucose

A simple sugar that cells can use as an energy source.

ATP

A molecule that stores and transfers usable energy within cells.

Light-dependent reactions

The first stage of photosynthesis, where light energy is captured and converted into chemical energy.

Calvin cycle

The stage of photosynthesis where carbon dioxide is used to produce carbohydrates.

Cellular respiration

The process cells use to release usable energy from glucose.

Glycolysis

The first stage of cellular respiration, where glucose is broken down into smaller molecules.

Aerobic respiration

Cellular respiration that requires oxygen.

Anaerobic respiration

Energy-producing processes that occur without oxygen.

Fermentation

An anaerobic process that allows cells to continue producing some ATP when oxygen is unavailable.

Homeostasis

The maintenance of stable internal conditions in an organism.

Digestive system

The system that breaks food down and absorbs nutrients.

Respiratory system

The system responsible for exchanging oxygen and carbon dioxide.

Circulatory system

The system that transports blood, oxygen, nutrients, hormones, and wastes around the body.

Excretory system

The system that removes metabolic wastes from the body.

Gas exchange

The movement of gases such as oxygen and carbon dioxide between an organism and its environment.

Nutrient absorption

The movement of digested nutrients into the bloodstream or lymph.

Blood vessel

A tube that carries blood through the body.