Ecosystems and Material Cycles Flashcards
What are the three types of nutrients cycle?
Carbon, water and nitrogen cycle
Why are the nutrients cycles important?
Carbon, water and nitrogen are essential to life and there is a fixed amount of nutrients on Earth which must be constantly recycled
How are materials cycle going though the living and non-living components of an ecosystem?
Organisms take in elements from their surroundings, elements converted to complex molecules which become biomass, elements transferred along food chain and elements returned to environment during excretion and decomposition of dead organisms
What are the stages of the carbon cycle?
Photosynthesis plants remove CO2 from the atmosphere, eating passes carbon compounds along the food chain, respiration in plants plants and animals returns CO2 to the atmosphere, organisms die and decompose, decomposers break down dead material and release CO2 via respiration and combustion of materials releases CO2
What are the stages of the water cycle?
Energy from the sun evaporates water from sources, transpiration also releases water vapour, water vapour rises, cools and condenses forming clouds, precipitation occurs, water is absorbed by the soil and taken up by roots, some is used in photosynthesis or becomes part of the plant, entering the food chain, excretion returns water to the soil and surface runoff returns to streams, rivers and eventually the sea
What is potable water?
Drinking water
How can potable water be prepared?
Desalination
What is desalination?
A process that removes salts from saline water
What are two methods of desalination?
Thermal desalination and reverse osmosis
What is thermal desalination?
Salt water is boiled, water evaporates, rises and condenses down a pipe and this separates pure water from salts
What happens is reverse osmosis?
Saline water pumped into a vessel containing a partially permeable membrane at high pressure, high pressure forces water molecules to move from an area of low water concentration to an area of high water concentration and pure water separated from salts
What do plants use to make proteins?
Nitrates
Why can’t nitrogen be used directly by plants to form proteins?
Nitrogen is unreactive
What are the four types of bacteria involved in the nitrogen cycle?
Decomposers, nitrogen-fixing bacteria, nitrifying bacteria and denitrifying bacteria
What is the role of decomposers in the nitrogen cycle?
Break down proteins and urea into ammonia and ammonia dissolves in solution forming ammonium ions
What is the role of nitrogen-fixing bacteria in the nitrogen cycle?
Convert nitrogen gas into ammonia and ammonia dissolves in solution forming ammonium ions
Where are nitrogen-fixing bacteria found?
Soil and root nodules of legumes
What type of relationships is exhibited between nitrogen-fixing bacteria and legumes?
Mutualistic relationship, plants receive ammonium ions from bacteria and bacteria gain sugars from the plants
What is the role of nitrifying bacteria in the nitrogen cycle?
Convert ammonium ions into nitrites and convert nitrites into nitrates
What is the role of denitrifying bacteria in the nitrogen cycle?
Convert nitrates into nitrogen gas
Where are denitrifying bacteria commonly found?
Waterlogged soils
What are the stages of the nitrogen cycle?
Lightning and nitrogen-fixing bacteria convert nitrogen gas to ammonia which dissolves to form ammonium ions, nitrifying bacteria convert ammonium ions to nitrate ions which are taken up by plants and used to build protein, feeding passes nitrogen through the food chain, organisms die and decompose, decomposers break down proteins and urea to form ammonia which dissolves to form ammonium ions and denitrifying bacteria convert nitrates in the soil back into nitrogen gas
How can the amount of nitrate in the soil be increased?
Using fertiliser and crop rotation replenishes nitrates that may have been depleted by the previous crop
What is decomposition?
The breakdown of dead materials into simpler organic matter
How do decomposers break down dead matter?
Decomposers release enzymes which catalyse the breakdown of dead material into smaller molecules
What factors affect the rate of decomposition?
Oxygen availability, temperature and water content
Why is oxygen required for decomposition?
Most decomposers require oxygen for aerobic respiration
How does the availability of oxygen affect the rate of decomposition?
As oxygen levels increase, the rate of decomposition increases but as oxygen levels decrease, the rate of decomposition decreases
Why can decomposition still occur in the absence of oxygen?
Some decomposers respire anaerobically but the rate is slower and produces less energy
How does temperature affect the rate of decomposition?
Decomposers release enzymes: rate highest at 50C, lower temperatures, enzymes work too slowly, rate decreases and high temperatures, enzymes denature and decomposition stops
How does soil water content affect the rate of decomposition?
Decomposers require water to survive: in moist conditions the rate of decomposition is high and in waterlogged soils there is little oxygen for respiration so the rate of decomposition decreases
What conditions are required to make compost?
Conditions that give a high rate of decomposition: plentiful supply of oxygen, warm and moist
What is the methods of food store used to slow down the rate of decomposition?
Stored in fridge/freezer to slow down the activity of microbes, stored in airtight cans to prevent the entry of microorganisms, high temperatures sterilised cans, destroyed any bacteria, adding salt or sugar kills microbes and food kept dry to reduce the ability of microorganisms to survive