Biology - Chapter 9 - Ecosystems and material cycles

If any part of an ecosystem changes, what happens?

Other parts of the ecosystem can be affected

What is the definition of habitat?

Where an organism lives

What is the definition of population?

All of the organisms of a species that live in that habitat

What is the definition of community?

All of the population of different species in the same habitat

What are biotic factors?

Living factors of the environment

What are abiotic factors?

Non living factors of the environment

What is the definition of ecosystem?

The interaction of a community of living organisms with the non living parts of the environment

What is interdependence?

All species depend on other species in some way

What is competition?

Organisms fighting for the necessary resources for survival

What is abundance?

How many organisms there are

What is distribution?

Where the organisms are

What is sampling?

Measuring a subset or organisms to make predictions about the entire population

What do quadrats do?

Measure abundance

What do transects do?

Measure distribution changes

What do food chains show?

What gets eaten by what in an ecosystem

What is a producer?

A photosynthetic organism

What do primary consumers eat?

They eat producers

What do secondary consumers eat?

They eat primary consumers

What do tertiary consumers eat?

They eat secondary consumers

What happens as the energy passes up the levels in a food chain?

Much of the energy is lost

What are trophic levels?

The different levels within a food chain

What are trophic level 1?

Producers - where all energy in a food chain comes from

What are trophic level 2?

Primary consumers - herbivores

What are trophic 3?

Secondary consumers - carnivores

What is an apex predator?

An organism that does not have any predators

What do omnivores eat?

Producers and animals

What are decomposers?

Bacteria

What are detritivores?

Worms

What do decomposers and detritivores do?

Decompose dead plant and animal matter in the environment and recycle the nutrients back into the ground

What do pyramids of biomass show?

The biomass of each trophic level in a food chain

What is biomass?

Mass of living organisms

What are three reasons as to why biomass may be lost?

Organisms do not consume it all, may not be absorbed, released through respiration

What is the equation for the efficiency of biomass transfer?

Biomass transferred / biomass available at previous level X 100

What is biodiversity?

The variety of different species on earth / within an ecosystem

What are the functions of biodiversity?

Stability, pollinators, medication

What is fertiliser?

A substance that is applied to soil in order to supply plants with nutrients

What are NPK fertilisers made up of?

Nitrogen, phosphorus and potassium

How does leaching occur?

When nutrients are washed out of the soil by water and enters lakes and rivers, which stimulates rapid algae growth

What does leaching result in?

Eutrophication

What is the process of eutrophication?

Nutrients from fertilisers stimulate rapid growth of algae, algae blocks light from reaching plants below, the lack of light prevents photosynthesis causing them to die, decomposers feed on matter and the population of decomposers increase causing oxygen decline, aerobic organisms die

What is the water cycle?

Energy from the sun causes water to evaporate, water vapour condenses into clouds, precipitation occurs

What is the carbon cycle?

Plants take in carbon dioxide from the atmosphere, this is passed onto animals. When animals decay, carbon dioxide is released. (when animals dont decay, they are burned as fossil fuels which releases carbon dioxide)

What does overfishing threaten?

The existence of many fish species in the world

What are fish farms?

Large enclosures / tanks that are designed to provide controlled environments for the growth of fish for human consumption

What happens in fish farms?

Large numbers of fish are bred in small enclosures and fed high quality food to maximise growth and reproduction rates, in order to meet demand

What is the nitrogen cycle?

Describes how nitrogen is recycled within an ecosystem and how it is converted between different chemical forms

What is the process of the nitrogen cycle?

Nitrogen fixation → nitrification → assimilation → decomposition → denitrification

What is the process of nitrogen fixation?

Atmospheric nitrogen in the air is converted into nitrates and ammonia

What produces nitrates in the process of nitrogen fixation?

Lightning

What produces ammonia in the process of nitrogen fixation?

Nitrogen fixing bacteria

What is nitrification carried out by?

Nitrifying bacteria in the soil

What is ammonia converted to in nitrification?

Nitrites

What is nitrites converted to in nitrification?

Nitrates

What is assimilation?

Plants absorbing nitrates and ammonium ions and using them to create biological molecules such as proteins

When does decomposition occur?

When decomposers feed on the waste excretions of animals and the rotting corpses of dead animals

What do decomposers convert urea and protein into?

Ammonia

What is denitrification?

When denitrifying bacteria in the soil converts nitrates back into atmospheric nitrogen

Why is denitrification bad?

As it means there are fewer nitrates in the soil, reducing the amount available for the plants to absorb and assimilate