Ecology: Key Concepts, Classification, Ecosystems, and Population Dynamics

What is an organism?

An individual living thing, such as a plant, animal, fungus, or bacterium.

What is the biosphere?

All parts of Earth where life exists: land, water, and parts of the air.

What is a species?

A group of similar organisms that can breed with one another and produce offspring.

What are four ways organisms may respond to environmental change?

They may adapt, migrate, hibernate, or die.

Name one human action that can reduce biodiversity.

Pollution, habitat destruction, or overhunting.

What are five ways humans use the environment?

For food, clothing, shelter, health, and fuel.

What is the classification order from broadest to most specific?

Domain, kingdom, phylum, class, order, family, genus, species.

What is the most specific classification level?

Species.

Which groups appear in the guide's kingdoms picture?

Animals, plants, fungi, protists, eubacteria, and archaebacteria.

Why does the guide say '5 kingdoms' but show six groups?

Older systems combine bacteria in one kingdom; the picture separates eubacteria and archaebacteria.

What are cells?

The basic units that make up living things.

What is a stimulus?

A change an organism can detect and respond to, such as light or heat.

What does it mean to respond to a stimulus?

To react to a change in the environment.

Why do organisms need energy?

To carry out life processes such as growth and movement.

What does reproduction mean?

Producing new organisms of the same species.

What is the difference between growth and development?

Growth means getting larger; development means changing as an organism matures.

Can movement happen inside an organism?

Yes. Movement can be internal, such as moving materials through the body, or external, such as walking.

What does biotic mean in ecology?

Living or once-living parts of an environment, such as a tree, fallen leaf, or dead animal.

What does abiotic mean?

A nonliving part of the environment that was never alive, such as water, sunlight, or rock.

What four processes does the guide emphasize while an organism is alive?

Movement, energy use, respiration, and response.

What is an ecosystem?

Living organisms and nonliving factors interacting in one area.

What is a food chain?

One path showing how energy moves from one organism to another.

What is a food web?

Several connected food chains.

What do arrows in a food chain show?

The direction energy moves: from the organism being eaten to the eater.

What is a producer?

An organism, such as a plant, that makes its own food.

What is a primary consumer?

An organism that eats a producer.

What is a secondary consumer?

An organism that eats a primary consumer.

What is a trophic level?

An organism's feeding position in a food chain or energy pyramid.

What is at the base of an energy pyramid?

Producers.

What is the 10% rule?

About 10% of energy at one trophic level becomes available to the next level.

If producers have 1,000 energy units, about how many reach primary consumers?

About 100 energy units.

Why is less energy available at higher trophic levels?

Organisms use much of their energy for life processes, and some is lost as heat.

What do decomposers do?

They break down dead material and recycle nutrients.

Name two common decomposers.

Fungi and bacteria.

What is ecological succession?

The gradual change in a community over time.

What is primary succession?

Succession that starts where there is no existing community or soil, such as bare rock.

What is secondary succession?

Succession after a disturbance where soil remains, such as after a fire.

What is symbiosis?

A close, long-term relationship between different species.

What is mutualism?

Both species benefit.

What is commensalism?

One species benefits; the other is neither helped nor harmed.

What is parasitism?

One species benefits; the other is harmed.

Which relationship benefits both species?

Mutualism.

Which relationship harms one species?

Parasitism.

What is a limiting factor?

Something that affects how large a population can grow.

What is a density-dependent factor?

A factor whose effect changes with population density, such as competition, predation, disease, or parasitism.

What is a density-independent factor?

A factor that can affect a population regardless of its density, such as a drought or storm.

What is predation?

A predator catches and eats prey.

What is competition?

Organisms try to use the same limited resource, such as food or space.

What is carrying capacity?

The largest population an environment can support over time.

What does a J-shaped growth curve show?

Exponential growth: the population increases faster and faster.

When can exponential growth happen?

When resources are abundant and limiting factors have little effect.

What does an S-shaped growth curve show?

Growth slows and levels off near carrying capacity.

What happens when birth rate is higher than death rate?

The population grows.

What happens when birth rate equals death rate?

Population size is roughly stable if migration is ignored.

What is a boom-and-bust pattern?

A sharp population increase followed by a sharp decrease.

What is a cyclical population pattern?

Population size rises and falls repeatedly, as in many predator-prey relationships.

In a predator-prey cycle, what often happens after prey numbers rise?

Predator numbers may rise later because more food is available.