organisation of an ecosystem

Define population

A group of organisms of the same species that live in the same area and can interbreed.

Define habitat

The specific place where an organism lives

define community

populations of different species that interacting

Define ecosystem

The interaction between the biotic and abiotic factors in an area

What do food chains show?

Food chains show the feeding relationships of different organisms and the flow of energy between the organisms.

Define biomass

The total mass of living material

What are trophic levels?

stages in a food chain

What do the arrows in a food chain represent?

The direction of biomass transfer

describe a Simple food chain

producer → primary consumer → secondary consumer → tertiary consumer

What is producer surplus?

An organism that makes its own food

what types of organism are Primary producers

Photosynthetic organisms, such as green plants and algae, that trap energy from the sun

what is a Primary consumer

An organism that feeds on producers

what is a Secondary consumer

An organism that feeds on primary consumers.

Tertiary consumer

An organism that feeds on secondary consumers.

Predator

An organism that hunts, kills, and feeds on other animals (prey).

Prey

An organism that is killed, and consumed by a predator.

describe the patterns of predators and prey in a stable community

number of predators and prey rise and fall in cycles

why are producers the first trophic level

● Producers provide all biomass for the food chain (production of glucose via photosynthesis). ● The rest of the food chain involves the transfer of this biomass.

What is a quadrat?

A square or rectangular sampling area used to estimate the abundance and distribution of organisms in a particular habitat.

What is a belt transect?

A linear sampling method used to study the distribution of organisms across a gradient

Mean (abundance of organisms)

The average number of organisms per unit area or volume

How is the arithmetic mean calculated?

Sum of each number of each organism/the total number of each type of organism.

Mode (abundance of organisms)

most populous organism

Median (abundance of organisms)

The middle value in a set of data when arranged in ascending or descending order, representing the organism that falls at the midpoint.

describe how materials cycle through the living and non-living components of an ecosystem

● Organisms take in elements from their surroundings e.g. soil, air. ● Elements converted to complex molecules which become biomass. ● Elements transferred along food chains. ● Elements returned to environment during excretion and decomposition of dead organisms.

3 Molecules cycled through ecosystems

Oxygen, carbon dioxide, and water

Describe the carbon cycle

• Plants fix carbon dioxide into organic molecules during photosynthesis.

• The organic carbon-containing molecules are passed onto organisms that eat the plants.

• Carbon dioxide is released back into the atmosphere by respiration from animals and plants.

• Burning fossil fuels also releases carbon dioxide into the atmosphere.

Importance of carbon cycle

Carbon-containing molecules such as glucose are important for living organisms to grow and provide energy for vital functions within cells.

Describe the water cycle

• Water from lakes and oceans evaporates.

• The evaporated water condenses into clouds and returns to earth as precipitation.

• The water from precipitation is useful for life on land.

• The water then returns to rivers and oceans through surface runoff.

Importance of water cycle

Living organisms require water and the water cycle provides organisms on land with a continuous supply of water.

Why are microorganisms important for the cycling of materials through an ecosystem?

Microorganisms (bacteria and fungi) return carbon to the environment by releasing carbon dioxide through respiration while they decompose dead matter. The decomposition of dead matter in soil returns mineral ions to the environment for other organisms to use e.g. plants use mineral ions for growth.

what is meant by Decomposition

The breakdown of dead organic matter into simpler organic matter

How do decomposers break down dead matter?

Decomposers release enzymes which catalyse the breakdown of dead material into smaller molecules.

2 Types of decomposition

Aerobic decomposition (with oxygen) anaerobic decomposition (without oxygen)

what Factors affect rate of decomposition

Oxygen availability temperature water content

Why is oxygen required for decomposition?

Most decomposers require oxygen for aerobic respiration

how does the availability of oxygen affect the rate of decomposition

● As oxygen levels increase, the rate of decomposition increases. ● As oxygen levels decrease, the rate of decomposition decreases.

Why can decomposition still occur in the absence of oxygen?

Some decomposers respire anaerobically *However, the rate of decomposition is slower as anaerobic respiration produces less energy

How does soil water content affect the rate of decomposition?

Decomposers require water to survive: ● In moist conditions the rate of decomposition is high. ● In waterlogged soils there is little oxygen for respiration so the rate of decomposition decreases.

Why does decomposition require water?

Water is required for the secretion of enzymes and absorption of dissolved molecules.

how does temperature affect the rate of decomposition

Decomposers release enzymes: ● Rate highest at 50°C (optimum temperature for enzymes). ● Lower temperatures, enzymes work too slowly, rate decreases. ● High temperatures, enzymes denature, decomposition stops.

How is the rate of change calculated when considering the decay of biological material?

Rate of change = Change in value Change in time Where value is a measurable variable associated with the decay of the material

Use of compost

Compost is used as a natural fertilizer improve soil fertility promote the growth of crops and garden plants.

what is compost

nutrient rich product of the rapid decay of waste biological materials in optimum conditions set by gardeners and farmers.

describe how biogas generators work

provide methane gas for fuel through anaerobic decomposition that occurs in animal waste

describe how environmental conditions affect communities

-Factors such as temperature, soil pH, and light intensity can influence the abundance and distribution of organisms within communities -rising global temperatures have been liked to the extinction of frog species (skin makes them more vulnerable to temp change)

how can different temperatures be bad for certain communities

too low temp= growth will be slower as organism will use more energy to stay warm. -temp too high= organism can die and water will become limited as evaporation increases

Detrimental impacts of sulfur dioxide

-formed when fossils fuels containing impurities burn -sulphur dioxide can dissolve in water to form acid rain which can erode buildings and pollute water sources

how can changes in water levels affect ecosystem

-animals may have to migrate to find water -melting ice caps= habitats destroyed

Detrimental impacts of carbon monoxide

carbon monoxide is formed from the incomplete combustion of fossil fuels. carbon monoxide binds irreversibly to haemoglobin which prevents it from carrying oxygen too much expose can cause unconsciousness and death

how can atmospheric gasses affect ecosystems

some organism cannot survive when certain gases are present. polluted water= causes illness to animals that drink it

Greenhouse gases

water vapour carbon dioxide nitrous oxide methane CFCs

Human activities contributing to greenhouse gases

burning fossil fuels deforestation large-scale livestock farming

how do Greenhouse gases lead to global warming

Greenhouse gases allow heat from the sun to enter atmosphere -act as a 'blanket' in the atmosphere and traps heat

state 3 negative consequences of global warming

sea level rise caused by melting icebergs disrupted farming and agricultural increases spread of diseases in warmer climates