Chapter 2 + case study

Species

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

Population

A group of the same species living in the same area at the same time.

Habitat

The environment where a species lives.

Niche

The role of an organism in its ecosystem.

Community

All organisms in an area.

Ecosystem

A community and its abiotic (non-living) environment.

Biotic factors

Living parts of an ecosystem (e.g., predation, disease).

Abiotic factors

Non-living parts of an ecosystem (e.g., pH, temperature, light).

Limiting factors

Things that slow population growth (e.g., space, food, disease).

Carrying capacity

Max number of individuals an area can support.

Producer (autotroph)

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

Consumer (heterotroph)

An organism that eats other organisms.

Decomposer

An organism that breaks down waste and dead matter (e.g., fungi).

Trophic levels

Feeding levels in an ecosystem (producer → primary consumer → secondary…).

Food chain

One path of energy through an ecosystem.

Food web

Many interconnected food chains.

Energy pyramid

A model showing energy distribution among trophic levels (10% energy rule).

10% Rule

Only approximately 10% of energy is transferred to the next trophic level.

Carbon cycle

The cycle involving photosynthesis, respiration, combustion, and fossil fuels.

Nitrogen cycle

A cycle including nitrogen fixation, nitrification, assimilation, and denitrification.

Water cycle

The cycle including evaporation, condensation, precipitation, and transpiration.

Biome

Large ecosystems characterized by specific temperature and precipitation patterns.

Zonation

Spatial patterns in a habitat caused by abiotic factors like salinity or exposure.

Succession

Change in ecosystems over time.

Climax community

The final stable stage of ecological succession.

Pioneer species

The first colonizers in a disturbed ecosystem.

Quadrat

A sampling method used to count organisms in a square area.

Transect

A sampling method using a line or belt to study species distribution.

Capture–mark–recapture

A method to estimate population size based on marked individuals.

Simpson’s Diversity Index

A measure of biodiversity calculated using the number of organisms and individuals per species.

Bioaccumulation

The build-up of a toxic substance in the body of one organism over time.

Biomagnification

The increase in concentration of a toxic substance as it moves up the food chain.