B9 | ecosystems & material cycles Flashcards
what is food security?
having access to enough food that is safe to eat and has the right balance of nutrition
role of photosynthesis in the carbon cycle
- plants take in carbon dioxide by photosynthesis
- plants make carbon compounds (glucose) from carbon dioxide
role of respiration in the carbon cycle
- plants release carbon dioxide during respiration
- plants are eaten by animals
- carbon from plants is passed to animals
- animals release carbon dioxide during respiration
role of decomposition in the carbon cycle
- microorganisms feed on dead plants and animals
- microorganisms release carbon dioxide during respiration and decomposition
role of combustion in the carbon cycle
- fossil fuels are formed from dead plants and animals
- fossil fuels contain stored carbon
- carbon dioxide is released into the atmosphere during combustion
what effect does burning fossil fuels have on the environment?
- causes an increase in carbon dioxide and other greenhouse gases
- heat is blocked from radiating back into space causing global temperature to increase (global warming)
- loss of biodiversity e.g. glaciers melting, loss of habitats
what is desalination?
the process of removing mineral ions (like sodium) from salt water to make it potable (drinkable)
water cycle
1) precipitation: rain, hail, sleet and snow falls from clouds producing freshwater for organisms
2) condensation: water vapour cools and turns into clouds
3) transpiration: evaporation and diffusion of water from the leaves of trees/plants
4) groundwater flow: when water flows through the rocks and soil underground
5) surface run-off: when water runs off the surface of the ground
6) evaporation: when the sun heats up water from the oceans and it goes up into the atmosphere
how does reverse osmosis work?
moves water into purification tanks under high pressure (water molecules move against concentration gradient)
water is forced through a partially permeable membrane leaving behind/removing salts from the water
role of decomposers in the nitrogen cycle
- decomposers are bacteria which breaks down dead organic matter
- they convert proteins into urea and ammonia
- ammonia is released into soil
- this increases nitrogen in the soil
role of nitrifying bacteria in the nitrogen cycle
- nitrifying bacteria converts ammonia into nitrites
- nitrites are then converted into nitrates
- which absorbed by plants to make proteins
role of nitrogen-fixing bacteria in the nitrogen cycle
- nitrogen-fixing bacteria turn atmospheric nitrogen into ammonia and ammonium ions under aerobic conditions
- found in the soil and in the root nodules of leguminous plants
- mutualistic relationship: plants protect bacteria from predators and bacteria provide nitrites to make proteins
- roots absorb nitrites by active transport
role of denitrifying bacteria in the nitrogen cycle
- converts nitrates back into nitrogen gas
- this happens when soil becomes waterlogged and occurs under anaerobic conditions
- increases the amount of nitrogen in the atmosphere
what is decomposition?
natural process of the breakdown of dead plant and animal matter/waste into simpler molecules such as carbon dioxide, water and mineral ions (carried out by bacteria or fungi)
how does temperature affect the rate of decomposition?
- high temperature = enzymes in microorganisms work faster/at optimum temperature & microorganisms reproduce faster
- temperature TOO high = denature of enzymes
- low temperature = enzymes don’t have enough energy to make reactions occur fast enough
how does oxygen availability affect the rate of decomposition?
microorganisms need oxygen for cell respiration
how does water availability affect the rate of decomposition?
decomposers need water to survive, reproduce and carry out biological processes
what is compost?
decomposed organic matter that is used as a natural fertiliser for crops and gardens – it recycles nutrients back into the ecosystem – improving plant growth
why do we freeze/refrigerate food?
decreases the temperature which prevents microorganisms from reproducing/stops enzymes from working (decreases rate of decomposition)
why do we dehydrate food?
reduces water availability for microorganisms which prevents them from reproducing and surviving (decreases rate of decomposition)
why do we store food in cans?
airtight cans prevents oxygen/new microorganisms from getting inside which prevents decomposition/reproduction (decreases rate of decomposition)
cans are also sterilised
why do we store food in salt water?
microorganism loses water due to osmosis (water moves from area of high concentration [organism/food] to area of low concentration [salt water]) which decreases rate of decomposition
why do we store food in oil?
prevents oxygen from getting to microorganisms which decreases rate of transpiration
how do fish farms in open water reduce biodiversity?
- food is added to nets to feed the fish which produces large amounts of waste
- this food and waste can leak into the water causing eutrophication/death of wild species
- fish farms in open water acts as a breeding ground for parasites which can infect both the fish and animals outside the farm
- predators such as sea lions are attracted to the farms, they can get caught in the nets and die
- fish can escape and cause problems for indigenous species
how does the introduction of non-indigenous species impact biodiversity?
- non-indigenous species compete with indigenous species for food and shelter
- sometimes the non-indigenous species are better at getting these resources and out-compete the indigenous species
- this causes a decrease in the indigenous species and eventually they die out
- non-indigenous species can also bring new diseases to a habitat where the indigenous species cannot survive them
how does eutrophic impact biodiversity?
- fertilisers containing nitrates are added to land and after it rains, they can run off into rivers and lakes
- fertilisers add excess nitrates into the water which causes algal bloom which blocks sunlight
- plants are unable to photosynthesise due to lack of sunlight and eventually they die and decompose
- microorganisms which feed on dead plants now have more food, therefore they multiply faster and use up all the oxygen in the water
- organisms that need oxygen for aerobic respiration die
how does the increase in animal farming and consumption of meat/fish affect food security?
grazing animals are fed food such as corn and wheat which could instead be eaten by humans
overfishing means there won’t be enough fish to catch in the future
how do environmental changes caused by human activity affect food security?
burning fossil fuels releases lots of carbon dioxide which traps energy in the atmosphere leading to global warming
global warming is a type of climate change which would then affect the growth of crops
soil pollution also affects the growth of crops
how does sustainability affect food security?
space which could be used to grow crops to eat is being used to grow crops for biofuel
increase in farming costs makes it too expensive for farmers to continue farming in the future
how do new pests and pathogens affect food security?
they can cause damage to crops and livestock
what do bloodworms and sludgeworms indicate about water quality?
polluted water
what do stoneflies and freshwater shrimps indicate about water quality?
clean water
what do large amounts of bushy lichen and black spot fungus indicate about air quality?
clean air
what do crusty lichen indicate about air quality?
polluted air
