organisation of an ecosystem

what do food chains show ?

show feeding relationships of different organisms + flow of energy between the organisms

define biomass

total mass of living material

what are trophic levels ?

stages in a food chain

what do arrow in a food chain represent ?

where energy is being passed

ex . arrow from grass to zebra shows grass gives energy to zebra

describe a simple food chain

producer - primary consumer - secondary consumer - tertiary consumer

what is a producer ?

organisms that makes it own food - always plants

what type of organisms are primary producers ?

photosynthetic organisms like green plants + algae that trap energy from the sun

what is a primary consumer ?

organism that feeds on producers

what is a secondary consumer ?

organism that feeds on primary consumers

what is a tertiary consumer ?

organism that feeds on secondary consumers

what is a predator ?

consumer that kills and eats other animals

what is prey ?

animal that is killed and eaten by another animal

describe the pattern of predators and prey in a stable community

the number of predators and prey rise and fall in cycles

why are producers the first trophic level?

• they provide all biomass for food chain ex production of glucose via photosynthesis

• rest of food chain involves transfer of this biomass

what is used to measure the abundance and distribution of organisms in an area ?

quadrat

what is used to study the distribution of organisms across a gradient ?

belt transect

when considering the abundance of organisms what is meant by the term mean ?

average number of organisms

how is the arithmetic mean calculated ?

sum of each number of each organism DIVIDED BY total number of each type of organism

what is mode when considering abundance of different organisms ?

most popular organism

what is mean when considering the abundance of organisms?

organism that represents middle value when numbers of each organism are arranged from lowest to highest

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

• organisms take in elements from the surroundings ex air , soil

• elements convert into complex molecules that become biomass

• elements is transferred along food chain

• element returns to environment during excretion + decomposition of dead animals

give 3 molecules that are cycle through ecosystems

• oxygen

• carbon dioxide

• water

describe the carbon cycle

• plants fix carbon dioxide into organic molecules during photosynthesis

• organic carbon containing molecules are passed onto organisms that eat plants ( herbivores / omnivores )

• carbon dioxide is released back into atmosphere by respiration from animals and plants

• burning fossil fuels also release carbon dioxide into atmosphere

why is the carbon cycle important ?

carbon containing molecules like glucose are important for living organisms to grow and provide energy for vital functions in cells

describe the water cycle ?

• water from lakes evaporates

• evaporated water condenses into clouds + returns to earth by precipitation

• water from precipitation is useful for life on land

• water returns to rivers and oceans through surface runoff

why is the water cycle important ?

living organisms require water and the water cycle provides organisms on land with continuous supply of water

what are microorganisms ?

tiny living things to small to seen with the eye ex germs

why are microorganisms important for the cycle of materials through an ecosystem ?

• ex bacteria and fungi , return carbon to environment by releasing carbon dioxide through respiration while they decompose dead matter

• decomposition of dead matter in soil returns mineral ions to environment for other organisms to use ex plants for growth

describe how environmental conditions affect communities

• things like temp , soil pH , light intensity affect abundance and distribution of organisms within communities

  ex . rising global temp has linked to extinction of frogs

how can different temps be bad for certain communities ?

• low temp could mean slower growth as organisms use more energy to keep warm

• high temp could mean organisms die as water becomes limited as evaporation increases

how can changes in water levels affect ecosystems ?

• animals may have to migrate to find water

• melting ice caps could destroy habitats of some animals ( icy regions )

how can atmospheric gases affect ecosystems ?

• some organisms cant survive when certain gases are present

• polluted water could cause illness to animals that drink it

what impact could sulfur dioxide have on the environment?

• formed when fossil fuels are burnt

• can dissolve in water to from acid rain which can erode buildings + pollute water sources

what impact can carbon monoxide have on the environment ?

• formed from incomplete combustion of fossil fuels

• binds irreversibly to haemoglobin which prevents it from carrying oxygen

• too much of it exposed can cause unconsciousness and death

name 5 green house gases

• water vapour

• carbon dioxide

• nitrous oxide

• methane

• CFCs

give 3 human activities that contribute to greenhouse gases

• burning fossil fuels

• deforestation

• large scale livestock farming

how do greenhouse gases lead to global warming ?

• allow heat from sun to enter atmosphere

• gases act as blanket and trap the heat in the atmosphere

state 3 negative consequences of global warming

• sea level rise caused by melting icebergs

• disrupted farming and agriculture

• increase spread of disease in warmer climates