Ecology and Biological Resources Flashcards
Define habitat
Place where an organism lives e.g. Rocky shore or a field
Define population
All the organisms of one species in a habitat
Define community
All different species in a habitat
Define ecosystem
All the organisms living in a particular area and all the non-living conditions e.g. Temp / climate
What is a quadrat
Square frame that encloses a known area
Used to estimate population size
Process of quadrat
Place quadrat (e.g. 1m) at random point
Count all organisms in quadrat
Multiply by total area (in m)
Problems with quadrats
May not be representative as it is random
May not be accurate so use bigger quadrats at multiple places and find mean
Explain how to use a quadrat to investigate distribution of organisms
Mark out line in area
Collect data along the line using quadrats placed next to each other (called transects)
what is a producer?
begging of food chain
produces their own food
what are decomposers ?
end of food chain
break down dead material and waste
what is a trophic level ?
each stage of good chain (e.g. producer)
trophics of a food chain
producer
primary/secondary/tertiary consumer
decomposer
explain why not all energy is transferred in food chains
some parts aren’t eaten (roots/bones)
some parts are indigestible (e.g. fibre)
lots is used to power life processes
most is eventually lost as heat
describe the water cycle
water evaporates (sun)
plants transpire water also
warm water cools and condenses to form clouds
water falls as precipitation
describe the carbon cycle
plants use CO² to photosynthesise
animals eat plants and die (as well as plants) and are broken down by decomposers
decomposers/animals/plants all respire, giving out CO²
products like wood and fossil fuels are burned (combustion) releasing CO²
describe decomposers (N² cycle)
break down proteins (dead matter) and urea and turn into ammonia
describe nitrifying bacteria
turns ammonia into nitrates
describe nitrogen-fixing bacteria
turns atmospheric nitrogen into nitrogen compounds
describe denitrifying bacteria
turns nitrates into nitrogen gas (no benefit)
where do the nitrogen bacteria live?
soil or nodules on plant roots
how does lightning play a part in the nitrogen cycle?
has enough energy to make nitrogen gas react with oxygen to form nitrates
how is carbon monoxide released?
usually car emissions (when hydrocarbons burn without enough oxygen)
why is carbon monoxide poisonous ?
combines with red blood cells and prevents them from carrying oxygen
how are cars made to reduce carbon monoxide emissions ?
fitted with catalytic converters that turn carbon monoxide int carbon dioxide
what causes acid rain?
sulfur dioxide (come from sulfur impurities in fossil fuels) which reacts with rain clouds to form dilute sulfuric acid
why is acid rain harmful?
causes lakes to become more acidic, killing organisms as they are sensitive to pH changes
kills trees by damaging leaves releasing toxic substances in soil, making it hard to take up nutrients
how has human activity increased CO² levels ?
car exhausts and burning fossil fuels
deforestation
how has human activity increased methane levels?
increase of rice growing and cattle rearing
how has human activity increased nitrous oxide levels?
released from soils after fertilisers used
vehicle engines and industry
what is CFCs?
how has human activity increased CFCs levels?
man made chemical previously used for aerosols and fridges
most countries agreed to stop however may still get released
describe eutrophication
fertilisers enter lake, adding nutrients
algae grow fast and block light
plants can’t photosynthesise so die
with more food, microorganisms feed on dead plants and reproduce rapidly, eventually depleting oxygen
organisms in lake die
explain another way of eutrophication
sewage goes into lake
sewage contains phosphates and nitrates
same process as fertilisers
how does deforestation affect leaching ?
trees removed and nutrients get leeched away but don’t get replaced, leaving infertile soil
how does deforestation affect soil erosion ?
tree roots hold soil together
when trees removed, soil can be washed away by rain and leave infertile ground
how does deforestation affect water cycle ?
trees stop rainwater reaching rivers too quickly
when they’re cut, rainwater flows straight into rivers, can cause floods
also makes local climate drier as trees transpire
how does deforestation affect carbon cycle ?
when trees cut and burned, it releases CO²
fewer trees means less photosynthesis so less CO² being used up
