SB9 Material Cycles Flashcards
What are the two processes that allows water to enter the atmosphere as water vapour?
- evaporation
- transpiration
What is the importance of the water cycle?
It distributes fresh water globally providing us with clean water for drinking
Describe the water cycle
- Water enters the atmosphere through transpiration or evaporation
- The warmer air of the atmosphere rises, taking the water vapour with it
- Since moist air cools down as it rises, water vapour forms clouds
- Water returns to Earth in a form of precipitation
Name the forms of precipitation
Rain, hail, snow or sleet
Define potable
Drinkable water
How can we produce potable water?
Filteration or chemical removal
How do we provide potable water for regions experiencing droughts regularly?
Through desalination
What is desalination?
Removing excess mineral ions from salts to make it drinkable
What are the methods of desalination?
- Distillation
- Reverse osmosis
Describe what happens in distillation
- saline water is boiled
- water vapour is funnelled through a tube before it is condensed
- pure water is collected
Describe what happens in reverse osmosis
Saline water is forced at a high pressure through a partially permeable membrane which filters out all the mineral ions leaving pure water
Give examples of materials that cycle through ecosystems
- water
- carbon
- nitrogen
When is carbon removed from the atmosphere?
Photosynthesis by plants and algae - used to make carbs. When they are consumed, carbon moves up the food chain
When is carbon returned to the atmosphere?
- When plants, animals and algae respire
- When combustion occurs
What is the importance of the carbon cycle?
- component of all organic molecules, many of which are responsible for sustaining life on Earth, such as glucose
- since there is only a limited amount of carbon available, the carbon cycle is an essential way of recycling the carbon we have available to us
Describe the carbon cycle
- Carbon removed from atmosphere through photosynthesis
- passed onto animals and decomposers due to feeding
- returned through respiration; in plants, animals and decomposing microorganisms
- additionally, returned by the combustion of fossil fuels
What are the four key processes of the nitrogen cycle?
- nitrogen fixation
- ammonification
- nitrification
- dentrification
Describe nitrogen fixation
Atmospheric nitrogen gas is converted into nitrogen-containing compounds such as ammonia, which forms ammonium ions (in solution) that can then be used by plants
What is nitrogen fixation carried out by?
- Nitrogen fixing bacteria
- Lightning
Describe nitrogen fixing bacteria
- found ‘free-living’ in soil and also in root nodules of certain plants (legumes)
- take n2 gas and change it into nitrates in the soil
How does lightning play a part in nitrogen fixing?
Splitting the bond between two atoms and turning them into nitrous oxides like N20 and NO2, which disolve in rainwater and ‘leach’ into the soil
Describe ammonification
Nitrogen compounds in waste products and dead organisms are converted into ammonia by decomposers
Describe nitrification
Ammonium ions in the soil are converted into nitrates by the nitrifying bacteria
Describe dentrification
Dentrifying bacteria use nitrates in the soil during respiration which releases nitrogen gas back into the atmosphere
Define decomposition
Breaking down and digestion of biological material by organisms called decomposers
What affects the rate of decay?
- temperature
- water availability
- oxygen availability
Why is decomposition a crucial process?
It returns important materials back to the rnvironment, such as carbon and mineral ions
How can decomposition be used in farming?
To make compost
What is compost used as?
A natural fertiliser, as it recycles the previously used minerals
What are the conditions required for decomposers to grow the best?
- warm
- moist
- lots of oxygen
How can we preserve food?
- drying food: adding salt/sugar (removes water)
- chilling/freezing (removes warmth required)
- pickling (changes pH)
- canning/ vacuum packing/ sealing in gases like N2 (prevents oxygen access)
- irradiation: kills decomposers
Define irradiation
Exposing something to radiation to kill microorganisms
Stat the equation for the rate of decomposition
mass lost/ number of days
What conditions ensure the best compost is produced?
- high temperatures: increase rate of enzyme controlled reactions
- water provided
- heap is turned to get more oxygen for the decomposers to respire
How can farmers increase soil fertility?
- adding manure
- adding artificial fertilisers
- crop rotation
How does manure increase soil fertility?
Increases the nitrates available in the soil
How does crop rotation increase soil fertility?
Planting crops with nitrogen fixing bacteria and digging in the roots after the crop is harvested. Decomposers break roots down and release nitrates for the next crop
