Ecosystems * Flashcards
What is the population?
all of the organisms of the same or closely related species in an area
What is a community?
two or more populations of organisms in an area
What is an ecosystem?
the interaction between a community of living organisms and their environment
What is a producer/autotroph?
an organism that makes its own food (usually a green plant)
What is a consumer/heterotroph?
an organism that eats ready-made food particles (ie a producer or another consumer)
primary/secondary consumer
What is a predator?
an organism that eats another consumer
What are prey?
an organism that is hunted and eaten by a predator
What are the three features of a pyramid of numbers?
What shape is it?
- the trophic level, starting from 1 at the bottom
- the population size inside each section of the pyramid, with the most at the bottom
- the species label, either inside each section or labelling each section
a triangle
What are the three features of a pyramid of biomass?
What shape is it?
- the trophic level, starting from 1 at the bottom
- the amount of biomass inside each section of the pyramid, with the most at the bottom
- the species label, either inside each section or labelling each section
a triangle
What are the three features of a pyramid of energy?
What shape is it?
- the tropic level, starting from 1 at the bottom
- the amount of energy inside each block
- the species label, either inside each section or labelling each section
different sized blocks stacked on top of each other
How do you calculate energy efficiency?
efficiency = energy available after/ energy available before x 100
How much energy is wasted at the producer level?
- some energy is used for metabolic reactions
- some doesn’t hit the chloroplasts
- only 1-5% is used to build new biomass
How much energy is wasted at the primary consumer level?
- some parts of a plant are inedible
- most passes through as cellulose
- some is used for metabolic reactions
- some used to maintain body temperature
- some used for muscle contractions
- some is excreted as waste
How much energy is wasted at the secondary consumer level?
- parts of prey can’t be eaten e.g. antlers
-some used for metabolic reactions - some used to maintain body temperature
- some used for muscle contractions
- some excreted as waste
What is a biotic factor?
living organisms in an ecosystem
What is an abiotic factor?
non-living physical and chemical elements in an ecosystem (the environment)
What is an indicator species?
an organism whose presence, absence or relative wellbeing in an environment shows the health of its ecosystem
What is air pollution?
What is an impact of air pollution?
burning fossil fuels emitts sulfur dioxide which gets soaked into clouds and falls as ‘acid rain’
this washes away many indicator species which shows the level of air pollution
What is evaporation?
solar energy from the sun heats the water and it rises as water vapour
What is condensation?
water vapour has risen and it cools to form clouds
What is precipitation?
when any form of water falls from a cloud
What is transpiration?
the movement of water through a plant and it exits as water vapour
What is infiltration?
when water has fallen as precipitation and is absorbed into the ground
What is surface runoff?
if a large volume of water falls on the ground, some water can run along the surface of the ground instead of being absorbed
What is respiration?
the process in living organisms that releases energy from glucose
6O2 + C6H12O6 –> 6CO2 + 6H2O
What is potable water?
drinkable water
What is desalination?
removing salt and other minerals from water to make it suitable for animal consumption or irrigation
What is reverse osmosis?
the movement of water from an area of low water concentration to an area of high water concentration
How is desalination carried out using reverse osmosis?
- salt water is forced at a high pressure into a vessel with a partially permeable membrane
- the pressure causes the water molecules to move in the opposite direction to osmosis
- water molecules pass across the membrane leaving the salt behind, so pure water is available for drinking
What is the carbon cycle?
when carbon is passed from the atmosphere as CO2, to living things, passed from one organism to the next, and returned to the atmosphere as CO2 again
How is carbon dioxide removed from the atmosphere?
green plants remove CO2 from the atmosphere through photosynthesis
the carbon becomes part of complex molecules inside the plant, like proteins and carbohydrates
How is carbon passed from one organism to the next?
- when an animal eats a plant, carbon from the plant becomes part of the fats and proteins in the animal
- decomposers feed on waste material from the animals and the remains of dead animals and plants, and the carbon becomes a part of these organisms
How is carbon dioxide returned to the atmosphere?
- organisms return CO2 to the atmosphere by respiration
- CO2 released by combustion - the burning of fossil duels releases large quantities into the atmosphere
What are the three key processes in the carbon cycle?
What does the carbon start as and end as in each process?
photosynthesis - CO2 –> glucose
respiration - glucose –> CO2
combustion (burning) - fuel –> CO2
What is nitrogen used for?
essential in the formation of amino acids which form proteins
How much nitrogen is in the air?
78%
Why can’t nitrogen be used directly by plants?
What do they use instead?
nitrogen is very unreactive
nitrogen can be converted to nitrates in the soil, which can be used by plants
What is the first stage of the nitrogen cycle?
nitrogen gas from the air is converted into ammonium ions by nitrogen fixing bacteria in the soil or root nodules
lightning reacts oxygen with nitrogen to form nitrate
What is the second stage of the nitrogen cycle?
ammonium ions are converted to nitrates by nitrifying bacteria in the soil
What is the third stage of the nitrogen cycle?
plants absorb nitrates from the soil and use them to build proteins
What is the fourth stage of the nitrogen cycle?
decomposers break down the bodies or waste of dead organisms meaning nitrogen is returned to the soil as ammonium ions
What is the fifth stage of the nitrogen cycle?
denitrifying bacteria in the soil break down nitrates and return nitrogen gas back to the air
What is nitrogen fixing bacteria?
converts nitrogen gas to ammonia which turns into ammonium ions
found in the soil or root nodules of legumes
What is nitrifying bacteria?
converts ammonia into nitrites then nitrates
found in the soil
What is denitrifying bacteria?
converts nitrates back into nitrogen gas
found in the soil
What are the two methods farmers use to increase the nitrate content of the soil?
- crop rotation
- using fertilisers
How does crop rotation improve soil fertility?
farmers grow legumes such as peas or beans, which can form nitrate as they have nitrogen fixing bacteria in their roots
one year the farmer will grow one of these crops and then in the following years will plant new crops in the nitrate rich soil, and rotate the different crops around the field
How does using fertilisers improve soil fertility?
natural fertilisers like manure or compost are used to provide a source of nitrate to increase the crop yield
artificial fertilisers like ammonium nitrate can also be applied to the fields
Give the five stages of eutrophication
1 excessive nitrates are leached into the river
2 plants flourish/alga bloom, which depletes oxygen in the water
3 algae prevents sunlight from reaching other plants which die and the oxygen is depleted further
4 dead plants are broken down by bacteria which uses up even more oxygen through respiration
5 oxygen levels become anoxic meaning no life is possible and all other organisms die
Which indicator species show a level of clean, some, moderate, high and very high water pollution?
clean - stonefly nymph, mayfly larva
some - freshwater shrimp, caddis fly larva
moderate - bloodworm, water louse
high- sludge-worm, red-tailed maggot
very high - no living insects
Which species indicate air pollution?
species of lichens and blackspot fungus are sensitive to air pollution, so they will not grow if there are high levels of sulfur dioxide (acid rain)
What is decomposition?
the breaking down of dead matter
What are decomposers?
bacteria and fungi that help the process of decomposition
What is the rate of decay?
How can it be estimated (what can you measure)?
the speed at which dead matter is broken down by decomposers
can be estimated by measuring changes in pH, change in mass or change in temperature
How does temperature effect the rate of decay?
at colder temps, decomposers will be less active so the rate of decomposition is low
as the temp increases decomposers become more active and the rate of decay increases
at extremely high temps the decomposers will be killed and decomposition will stop
when decomposers break compost down the heap becomes warmer due to the respiration of the decomposers generating heat
How does the volume of water effect the rate of decay?
with little or no water there is less decomposition because the decomposers cannot survive
as the volume of water increases the rate of decomposition also increases
many decomposers secrete enzymes to absorb or dissolve molecules and without water these reactions cannot occur
How does the level of oxygen effect the rate of decay?
with little or no oxygen there is less decomposition because the decomposers cannot survive - they need oxygen to respire
as the volume of oxygen increases the rate of decomposition also increases
How do you calculate the rate of change?
rate of change = change in value/ change in time
What are 3 pros and cons of fish farming?
pros :
- fish are a good source of protein
- less impact on open waters so no marine habitats are effected
- only the required fish are killed - other methods can kill lots of other organisms
cons:
- the fish are kept in very small tanks
- fish dont have the choice to live in artificial conditions
- giving the fish growth hormones isnt natural so its not an organic source of food for us
What is the impact of fish farming on biodiversity?
fish farming doesnt affect ,arine ecosystems and food chains
however fish are inbred which reduces their biodiversity and results in genetic spcies
What are 2 pros and 1 con of non-indigenous species?
pros:
- species can be introduced to eat a harmful naturally occurring species - biological control
-no pesticides or chemicals are used
cons:
- if left alone the populations of non-indigenous species can interfere with the ecosystem, damaging habitats or causing other naturally occurring species to die out
What is interdependance?
all organisms depend on each other
protecting one organism means protecting many
What is ecosystem stability?
by preserving ecosystems they’re remaining as they should be
What are potential recources?
what undiscovered cures could be destroyed if we dont look after ecosystems
What are rights/responsibilities?
all organisms have a right to life and we have a responsibility to leave earth as we found it
What are the five issues affecting food security?
-rising human population
- increasing animal and fish farming
- the impact of new pests and pathogens
- environmental change caused by human activity
- sustainability issues
What are biofuels?
growing crops to provide an alternative fuel source which is renewable
e.g. bioethanol made from fermenting sugar in corn
What is food security?
when everyone has access to safe and healthy food
What is mutualism?
a symbiotic relationship where all species involved benefit
What is parasitism?
a symbiotic relationship where one organism benefits by feeding off a host organism causing harm
What is parasitism?
a symbiotic relationship where one organism benefits by feeding off a host organism causing harm
Give an example of mutualism
oxpecker birds and zebras - the oxpecker bird eats ticks and flies on the zebra, which reduces the risk of disease
Give an example of parasitism
What adaptations does the parasite have?
a tapeworm inside the intestines
- hooks and suckers to attach to intestine wall
- flattened body so increased surface area for absorption of digested food
