Inv. 14/15 Ecology Study Guide

Individual

A single organism of a species, e.g., one deer in a forest.

Population

A group of individuals of the same species living in the same area and interacting, e.g., a herd of deer in a forest.

Community

All the different populations of organisms living and interacting in an area, e.g., deer, trees, birds, and insects in a forest.

Ecosystem

The community of organisms in an area along with their non-living environment, e.g., a forest with deer, trees, birds, soil, water, and sunlight.

Biome

A large geographic area with similar climate, plants, and animals, e.g., a temperate deciduous forest.

Biosphere

The part of Earth where life exists, including all biomes and ecosystems.

10% Energy Rule

Only 10% of energy is passed to the next trophic level; the rest is lost as heat.

Producers (Autotrophs)

Organisms that convert sunlight into energy, e.g., plants and algae.

Primary Consumers (Herbivores)

Organisms that eat producers.

Secondary Consumers (Carnivores/Omnivores)

Organisms that eat primary consumers.

Tertiary Consumers (Top Predators)

Organisms that eat secondary consumers.

Decomposers

Organisms like bacteria and fungi that break down dead organisms, recycling nutrients.

Detritivores

Organisms like earthworms and crabs that eat decomposing organic matter, recycling nutrients.

Food Chain

A linear flow of energy in an ecosystem.

Food Web

A complex network showing multiple feeding relationships and energy flow in an ecosystem.

Carbon Cycle

The process by which carbon is cycled through the environment via photosynthesis, respiration, decomposition, and combustion.

Nitrogen Cycle

The process involving nitrogen-fixing bacteria converting atmospheric nitrogen into usable forms and recycling nitrogen back into the soil.

Mutualism

An ecological relationship where both species benefit, e.g., bees pollinating flowers.

Commensalism

An ecological relationship where one species benefits and the other is unaffected, e.g., barnacles on whales.

Parasitism

An ecological relationship where one species benefits and the other is harmed, e.g., tapeworms in intestines.

Predation

An ecological relationship where one organism hunts and consumes another, e.g., wolves and deer.

Competition

An ecological relationship where two species compete for the same resources, affecting survival.

Keystone Species

A species that has a disproportionate effect on ecosystem stability, e.g., sea otters controlling sea urchin populations.

Primary Succession

The process of ecosystem development occurring on bare rock with no soil present, e.g., after a volcanic eruption.

Pioneer Species

The first organisms to colonize an area during primary succession, e.g., lichens and mosses.

Secondary Succession

The process of ecosystem development that occurs in disturbed areas with existing soil, e.g., after a wildfire.

Climax Community

A stable, mature ecosystem that develops over time.

Exponential Growth

Population growth that occurs rapidly (J-Curve) when resources are abundant.

Logistic Growth

Population growth that slows as it reaches carrying capacity (S-Curve).

Carrying Capacity

The maximum number of individuals an environment can support.

Density-Dependent Factors

Factors such as competition, predation, disease that increase with population size.

Density-Independent Factors

Factors such as natural disasters and climate changes that affect populations regardless of size.

Ecological Pyramids

Diagrams that show energy, biomass, and numbers at each trophic level.

Predator-Prey Relationships

Interactions between predator and prey populations that cycle in response to one another.

Effects of Disruptions

Consequences which include changes in food webs, loss of biodiversity, and altered biogeochemical cycles.

Succession and Stability

The process that shows how ecosystems recover over time, though human actions can slow or prevent recovery.