Ecology and Ecosystem Dynamics: Key Concepts and Relationships

What is a species?

A group of organisms that can breed and produce fertile offspring

Define abiotic factors and give two examples.

Abiotic factors are non-living parts of an ecosystem that affect living organisms. Examples: sunlight, water.

Define biotic factors and give two examples.

Biotic factors are living parts of an ecosystem that affect other organisms. Examples: plants, animals.

What do food chains display?

Food chains show how energy and nutrients flow from one organism to another in an ecosystem.

Give an example of a food chain starting with the sun and including four organisms.

Sun → Grass → Mouse → Snake → Hawk

What is a trophic level?

A trophic level is the position an organism occupies in a food chain, based on how it gets its energy.

What does "trophic" mean?

"Trophic" relates to feeding or nutrition.

Identify the role of a producer in an ecosystem.

Producers make their own energy through photosynthesis and provide energy for other organisms. Example: plants.

Identify the role of a consumer in an ecosystem.

Consumers eat other organisms to get energy. Examples: herbivores, carnivores, omnivores.

Identify the role of a decomposer in an ecosystem.

Decomposers break down dead organisms and recycle nutrients back into the soil. Examples: fungi, bacteria.

How much energy is transferred from one trophic level to the next?

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

Why does the grass population increase if the mouse population decreases?

If fewer mice eat the grass, there is less grazing, so the grass population can grow.

What is an autotroph?

An organism that makes its own food from sunlight or chemicals.

Name two types of producers.

Plants (use photosynthesis), Algae (use sunlight in water).

What are consumers or heterotrophs?

Organisms that cannot make food and eat other organisms.

Name the four classes of heterotrophs and what they eat.

Herbivores - plants, Carnivores - animals, Omnivores - plants & animals, Decomposers - dead organisms/waste.

Name two types of decomposers.

Fungi and Bacteria.

What is an energy pyramid?

Diagram showing energy flow through trophic levels in an ecosystem.

What is a food web?

Network of connected food chains showing energy flow.

How is chemical energy measured?

In calories or joules.

What effect do predators have on ecosystems?

Control prey populations, keeping ecosystems balanced.

What is the focus of population dynamics?

How populations change in size over time.

What is a habitat?

The natural place where an organism lives.

Factors affecting population size (examples)?

Habitat, Migration, Immigration, Emigration, Birth, Death.

What are open systems?

Systems that exchange matter and energy with surroundings.

What are limiting factors?

Factors that restrict population growth or distribution.

How can abiotic factors affect population size?

limit population sizes by determining survival, reproduction rates, and habitat suitability

How can biotic factors affect population size?

Food, predators, disease, and competition affect survival.

What is a niche?

An organism's role in its ecosystem.

How do invasive species affect ecosystems?

Reduce biodiversity by outcompeting natives and disrupting balance.

Define carrying capacity.

Maximum number of organisms an environment can support.

Patterns of population growth?

Exponential - unlimited growth, Peak - rise then crash, Logistic - slows near carrying capacity.

Primary vs. Secondary succession?

Primary - no soil, pioneer species first. Secondary - soil exists, ecosystem recovers.

What is symbiosis?

Close interaction between two species affecting at least one.

Types of symbiotic relationships?

Parasitism - one harmed, Commensalism - one benefits, Mutualism - both benefit.

Predator-prey relationship?

Predator hunts prey; controls populations and maintains balance.

Levels of ecological organization (largest to smallest)?

Biosphere, Ecosystem, Community, Population, Organism, Cell.

Energy pyramid levels from top to bottom (example organisms and energy)?

Quaternary Consumer - Hawk - 0.1%, Tertiary Consumer - Snake - 1%, Secondary Consumer - Frog - 10%, Primary Consumer - Grasshopper - 100%, Producer - Grass - 100% sunlight captured.

How does competition affect an ecosystem?

Limits resources, reduces population, forces adaptation.

How does globalization affect biodiversity?

Spreads invasive species, pollution, habitat loss; reduces biodiversity.