Ecosytems Flashcards
(22 cards)
What things act as decomposes (3)
- microorganisms
- bacteria
- fungi
Do microorganisms contribute CO2 to the atmosphere
Yes as they respire
What do microorganisms feed on
Plant and animal material
Why do microorganisms feed on material
For growth and other life processes
What happens when decay is prevented
Fossil fuels are formed.
What do fossil fuels store
Energy in carbon compounds
What nutrients are released in decay
Nitrates and phosphates
What are nutrient cycles like in stable communities
The processes that remove materials are balanced by the processes that return materials.
How is carbon released into the atmosphere
- combustion of fossil fuels
- respiration
How is carbon absorbed from the atmosphere (biology) (2)
- photosynthesis
- passed to animals when they eat plant (forms their carbohydrates, fats and proteins)
What enzyme converts urea to ammonia
Urease
What things can be converted into ammonia
Protein and urea
What can ammonia be converted to
Nitrates
Nitrogen fixation
Nitrogen from the air is converted to nitrates.
Where does nitrogen fixation occur
In free living bacteria in the soil and in bacteria in root nodules of legume plants. Or lightning
Denitrification
Break down of nitrates into nitrogen gas
Denitrifying bacteria
Some bacteria in the soil break down nitrates into nitrogen gas
Where do denitrifying bacteria usually live
Waterlogged/unploughed soil
What factors affect bacterial action and influence decomposition (4)
- temperature
- oxygen
- pH
- heavy metals
What are the effects of rising human population (3)
More space is needed for
- housing
- agriculture
- industry
Advantages of intensive farming
- increased crop yield and high levels of meat production
Disadvantages of intensive farming (3)
- fertilisers and pesticides - chemicals being washed from soil to waterways
- disease control - excess use of antibiotics in animals causes increased bacterial resistance
- battery methods - negative effect on animal welfare
