Ecosystem key terms and Competition

Laura Armstrong & Joe Wolfensohn

Teachers

Key Definitions in Ecology

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Competition in Ecology

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Laura Armstrong

Head of Biology

Joe Wolfensohn

Assistant Head of Biology

Recall Questions

This topic requires prior knowledge of basic ecology definitions.

What is a habitat?

The place where an organism lives.

What is an adaptation?

A feature that helps an organism survive in its environment.

What is competition?

Interactions between organisms in which both require a resource that is in limited supply (such as food, water, or territory)

Topic Explainer Video

Check out these @JoeDoesBiology videos that explain ecosystem key terms and competition, then read the study notes. Once you’ve gone through them, don’t forget to try the practice questions!e

Key Definitions in Ecology

Term	Definition
Ecosystem	The interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment.
Population	All the organisms of one species living in a habitat.
Community	All the different species living in a habitat.
Interdependence	How organisms in a community rely on each other for food, shelter, pollination, seed dispersal, etc.
Competition	The struggle between organisms to get enough resources to survive and reproduce.
Abiotic factors	The non-living parts of an ecosystem (e.g., light, temperature, moisture).
Biotic factors	The living parts of an ecosystem (e.g., predators, food availability, pathogens).
Habitat	The place where an organism lives.
Stable community	A community where population sizes and environmental conditions stay relatively constant over time (e.g., ancient oak woodland).

Competition in Ecology

Competition happens when organisms need the same limited resources.
It affects population sizes:

If resources are plentiful, more organisms survive and reproduce.
If resources are limited, some organisms will not get enough to survive, so the population size decreases.

If a species is better adapted to compete, it may outcompete another species and cause its numbers to fall.

What Do Animals Compete For?

Food
Water
Mates (if they are the same species)
Territory / shelter

What Do Plants Compete For?

Light
Space
Water
Mineral ions from the soil

Exam Tip

Don’t confuse population, community, and ecosystem. Remember:

Population = one species in a habitat.
Community = all living species in a habitat.
Ecosystem = interaction between the community (living factors) and the non-living factors in a habitat.

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