B4: Community-level Systems Flashcards
1 MARK
What is an Ecosystem?
An ecosystem is made up of all the living organisms and physical conditions in an area.
2 MARKS
what is a community?
And what is where they live called?
A community is the organisms within the ecosystem.The area they live in is the habitat.
1 MARK
Meaning of population
The total number of organisms of each species in a habitat.
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What 3 groups can u divide organsims in a community by?
P.C.D
producers- make their own food by photosynthesis(algae and plants)
consumers- Cannot make their own food and have to eat other organisms to gain energy.All animals are consumers
Decomposers- Gain energy by feeding in dead or decaying material
How is energy transferred between organsims?
-energy from sun by light to the chlorophyll in the cell of a producer
-co2 and water react to produce glucose which stores energy in its chemical bonds
-glucose can be used to be converted into carbs,fats and proteins.-used for growth and repair
-as an organism grows it increases biomass(mass of living material present).
Consumers then eat producers and when organism respires,energy stored in its food is transferred in the production of ATP.Organism grows and biomass increases.
What is a food chain
displays what organisms eat
Arrow in food chains represent transfer of biomass/energy
Each step in the food chain is a trophic level
Order of food chain
Producer-primary consumer-secondary consumer-tertiary consumer
What is a food web
only shows organisms eating one food source. For example a sparrow eats slugs,snails and worms
What factors affect an ecosystem
Biotic- living factors: animals/plants/trees
Abiotic-non-living/physical factors: rainfall/temperature/soil ph
How does light intensity affect communities
Needed for photosynthesis
Greater light, greater success of a plant
temp affect on communities
Effects the enzymes that control metabolic reactions
Plants will develop more rapidly as metabolism will be quicker with higher temp.
Also true for warm blooded animals(ectotherms) which rely on sun to keep them warm.
moisture level affect on communties
-lack of water leads to death as water is the main component for blood plasma
-plants will wilt as they need water to keep cells turgid and for photosyntheis
soil ph affect on communities
affects biological activity in soil and availability of certain minerals.
some plants grow better in acidic soils.-ferns
others grow better in alkaline soils-cauliflower
what is competition
when plants and animals compete for limited resources.Leads to weaker and animals dying or leaving the area,and weaker plants dying.
what do plants need to survive
light
water
minerals
space
co2
what do animals need to survive
food
water
mates
shelter
territory
what is population?
the number of organisms of each speices living in an area.
what is the interactions between orgainsms called
ecological relationships
what is interdependence
the word to describe how different organisms rely on eachother within a community
predation
name given to relationship between predator and pray.
when pred pop high=prey pop low
pred pop low=pred prop low-prey increase
cyclic relationship.
mutualism
both organisms beneffiting from the relationship.
birds and buffalo
paratism
when only one organism benefits (parasite) and other (host) is harmed.
tapeworms and humans
what is a flaw of food chains
do not show organisms involved
does not show size of biomass transferred
what do pyramids of numbers show?
population at each trophic level
the width=number of organisms present in each trophic level
what is biomass
amount of living material in an organism
what happens in the pyramid of numbers
as you go along,size of organisms generally increases.However there are fewer and fewer organisms at each level
what can u take into account by plotting the amount of biomass in each tropic level
number and size of organisms present
why does biomass decrease at each tropic level
energy is trnasferred to prodcuers by sunlight.
only 1% is transferred into chemical stores where most of the light is reflected from the leaf.
most of remaining energy is limited by factors like temp or water availability.
up to half the remaining energy is transferred in order to increase the plants biomass
why do scientists ususlaly calculate the dry mass of an organism
as water contents can vary between individuals.
Animals must be dead and dried in a kiln
what is the general percentage of biomass transferred between tophic levels
10%
how is biomass lost
not all of an organism is eaten-plant roots or animal bones cant be consumed
respiration- produces ATP and this is used by muscles for movement.Also causes thermal energy to transfer to the environment
egestion-some parts of an organism cant be digested and are removed from the body by faeces
excretion-waste products released through excretion and water lost through urine
what happens at each stage of the food chain
energy transferred decreases.
formula for efficecny of biomass transfer
efficency=
biomass after transfer/biomass before transfer X100
nutrient cycling
-plants obtain nutrients needed from the soil
-passed onto animals when plant is eaten
-when plants die,decomposers release the trapped nutrients back to the soil and absorbed by other plants
-some into the atmosphere
-in this process materials are passed between the abiotic and biotic compnents of an ecosystem
materials that are cycled-carbon
one of the most elements in organisms
used to make carbs,fats,proteins and DNA
cycles between atmosphere,living organisms and fossil fuels
can also become trapped in oceans and rocks
materials cycled-nitrogen
-Plants absorb nitrates (a form of nitrogen) from the soil through their roots to grow. They do this with the help of bacteria living in their roots (called root nodule bacteria).
-Plants can also absorb nitrogen from the air.
-Farmers may add fertilisers (containing extra nitrates) to the soil, which plants can absorb.
-The nitrogen is passed-on to animals that eat the plants.
-When plants and animals die, bacteria recycle nitrogen back into the soil through decomposition.
-When lightning strikes soil, nitrogen is released back into the air.
nutrient cycling-water
-Water evaporates from the Earth’s surface, before rising up into the atmosphere.
-Once in the atmosphere, the water vapour cools and condenses into either rain or snow. This eventually returns to the Earth’s surface.
-The rain or snow will either become surface runoff (water flowing off land) or will travel through the earth as ground water.
-Plants take up water through their roots.
what is the carbon cyce
process by which carbon is cycled through the atmosphere,earth,plant and animals,
process of carbon cycle
-Carbon is removed from the atmosphere by producers (e.g. algae) who use it in photosynthesis.
-By consuming plant matter, animals obtain carbon compounds.
-Carbon is returned into the atmosphere (as carbon dioxide) because of the respiration that happens in plant and animal cells.
-When animals and plants die, decomposers return the carbon locked in their bodies back to the atmosphere via decay.
-Combustion of fossil fuels is another source of carbon entry into the atmosphere.
how is carbon removed from the atmosphere?
during photosynthesis- converts carbon dioxide and water into glucose and oxygen.
