Nutrient Cycles Flashcards
Name 3 ways in which CO2 is removed from the atmosphere
- Photosynthesis
- Absorption into oceans
- Diffusion into soil
Name 3 ways in which CO2 is returned to the atmosphere
- Respiration
- Combustion of fossil fuels
- Deforestation
Why does the CO2 conc fluctuate daily?
- conc is lower in day as photosynthesis is occuring
- higher at night as no photosynthesis and more burning of fossil fuels
What is the Greenhouse Effect?
Greenhouse gases trap heat close to earth’s surface, keeps average temp of 17 degrees
How is carbon dioxide different to other greenhouse gases?
- a lot more of it
- remains in atmosphere for much longer (100 years)
How is methane produced?
When microorganisms break down organic molecules
Give some consequences of global warming
- rising sea levels; low lying land will flood
- melting of ice caps; extinction of species
- change in temp, rainfall, timing of seasons may affect crops
- distribution of species will change
What carries out nitrogen-fixation?
- free living bacteria
- mutualistic bacteria; live on root nodules and obtain carbohydrates from plant in return of amino acids
What is nitrification?
Process by which ammonium ions are converted to nitrite ions, and then into nitrate ions.
How are nitrate ions taken up by plants?
By active transport
What causes denitrification?
- when oxygen levels of soil decrease, becomes waterlogged
What carries out ammonification?
Saprobiotic microorganisms
Why are fertilisers used in agricultural ecosystems?
- mineral ions/faeces/decaying remains of plants and animals are not returned to soil because crop is harvested
- levels are replenished with fertilisers
What are artificial fertilisers made from?
- material mined from rocks and blended to form good balance of minerals
What are the effects of using nitrogen fertilisers?
- reduced species diversity; nitrogen rich soil favours growth of certain species (grasses), outcompete other species
- leaching
- eutrophication
