Ecosystems

Ecosystem

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

Producer

An organism that makes its own food through photosynthesis (e.g., plants, algae).

Consumer

An organism that eats other organisms to gain energy.

Autotroph 

An organism that produces its own food from sunlight or chemical energy.

Heterotroph

An organism that cannot make its own food and must consume other organisms.

Herbivore

An animal that eats only plants (e.g., rabbit).

Carnivore

An animal that eats only other animals (e.g., lion).

Omnivore

An animal that eats both plants and animals (e.g., bear).

Predator 

 An organism that hunts and eats other organisms.

Prey

An organism that is hunted and eaten by a predator.

Parasite 

An organism that benefits at the expense of its host (e.g., tapeworm).

Host

An organism that a parasite lives on or in, providing it with resources.

Symbiosis

A close relationship between two species that live together.

Mutualism

A type of symbiosis where both species benefit.

Commensalism 

A type of symbiosis where one species benefits and the other is unaffected.

Parasitism 

A type of symbiosis where one species benefits and the other is harmed.

Competition 

When organisms compete for the same resources like food, space, or mates.

Decomposer 

Organisms that break down dead material and recycle nutrients (e.g., fungi, bacteria).

Scavenger

An organism that eats dead animals (e.g., vulture).

Biotic

Living components of an ecosystem.

Abiotic 

Non-living components of an ecosystem (e.g., sunlight, water, temperature).

Food chain 

A sequence showing how energy flows from one organism to another through feeding relationships.

Food web 

A network of interconnected food chains showing energy flow in an ecosystem.

Energy flow 

The transfer of energy from producers to consumers and decomposers, with energy lost as heat at each level.

Photosynthesis

The process by which plants convert sunlight, water, and CO₂ into glucose and oxygen.

Cellular respiration

The process by which organisms break down glucose to release energy (ATP), carbon dioxide, and water.

Carbon cycle 

The movement of carbon through the atmosphere, living organisms, oceans, and the Earth.

Water cycle

The movement of water through evaporation, condensation, precipitation, and collection.

Introduced species 

A species that has been brought into a new ecosystem by humans, which can disrupt the balance.

Communities

All the different species living together in one area.

Population changes over time

How the size of a population increases or decreases because of births, deaths, immigration, and emigration.

Sampling techniques 

Methods used to estimate how many organisms live in an area.

Mark–recapture –

A method where animals are caught, marked, released, then caught again to estimate population size.

Human impacts 

The ways humans change ecosystems, like pollution, habitat loss, and deforestation.

Natural disasters 

Sudden events like fires, floods, or storms that can quickly change ecosystems.

Inhibition 

When one organism stops another from growing or surviving (often by releasing chemicals).

1st-level consumer

An organism that eats producers (usually herbivores).

2nd-level consumer

An organism that eats 1st-level consumers.

3rd-level consumer

An organism that eats 2nd-level consumers (top predators).

Carrying capacity

The largest number of organisms an environment can support without running out of resources.

Chloroplast 

The plant cell part where photosynthesis happens.

Chlorophyll

The green pigment in plants that absorbs sunlight.

Stomata

Tiny holes in leaves that let gases move in and out.

Mitochondria

The part of the cell that releases energy from food (cellular respiration).

Greenhouse gases

Gases that trap heat in the atmosphere, like CO₂ and methane.

Enhanced greenhouse effect 

Extra warming caused by humans adding more greenhouse gases to the atmosphere.

Introduced species

A species brought into a new place by humans that didn’t naturally live there.