7.2 Ecology (organisation of an ecosystem 2) Flashcards
Why are microorganisms important for the cycling of materials through an ecosystem?
- microorganisms (bacteria and fungi) return carbon to the environment by releasing carbon dioxide through respiration while they decompose dead matter
- the decomposition of dead matter in soil returns mineral ions to the environment for other organisms to use
What is meant by decomposition?
the breakdown of dead materials into simple organic matter
How do decomposers break down dead matter?
decomposers release enzymes which catalyse the breakdown of dead material into smaller molecules
What are the two types of decomposition?
- aerobic decomposition (with oxygen)
- anaerobic decomposition (without oxygen)
What factors affect the rate of decomposition?
- oxygen availability
- temperature
- water content
Why is oxygen required for deomposition?
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
- as oxygen levels decrease, the rate of decomposition decreases
Why can decomposition still occur in the absence of oxygen?
- some decomposers respire anaerobically
- however the rate of decomposition is slower as anaerobic respiration produces less energy
How does soil water content affect the rate of decomposition?
decomposers require water to survive:
- in moist conditions the rate of decomposition is high
- in waterlogged soils there is little oxygen for respiration so the rate of decomposition decreases
Why does decomposition require water?
water is required for the secretion of enzymes and absorption of dissolved molecules
How does temperature affect the rate of decomposition?
- the optimum temperature is 50 degrees celsius
- lower temperature, enzymes work too slowly, rate decreases
- higher temperatures, enzymes denature, decomposition stops
How is the rate of change calculated when considering the decay of biological material?
rate of change = change in value / change in time
What is compost?
the nutrient-rich product of the rapid decay of waste biological material in optimum conditions set by gardeners and farmers
How is compost used?
used as natural fertiliser to promote growth of crops or garden plants
Describe how biogas generators work
biogas generators provide methane gas for fuel through anaerobic decomposition that occurs in animal waste
Describe how environmental conditions affect communities
environmental conditions affect the abundance and distribution of organisms within communities
How can different temperatures be bad for certain communities?
- if the temperature is too low, growth will be slower as organisms will use more energy to stay warm
- if the temperature is too high, organisms can die and water will become limited as evaporation increases
How can changes in water levels affect ecosystems?
- animals may have to migrate to find water
- melting ice caps may destroy the habitats of some animals
How can atmospheric gases affect ecosystems?
- some organisms cannot survive when certain gases are present
- polluted water can cause illness to animals that drink it
How is carbon monoxide formed?
from the incomplete combustion of fossil fuels
What detrimental impacts can carbon monoxide have on the environment?
- carbon monoxide binds irreversibly to haemoglobin which prevents it from carrying oxygen
- too much exposure can cause unconsciousness and death
Name 5 greenhouse gases
- water vapour
- carbon dioxide
- nitrous oxide
- methane
- CFCs
Give 3 human activities that contribute to greenhouse gases?
- deforestation
- burning fossil fuels
- large scale livestock farming
How do greenhouse gases lead to global warming?
- greenhouse gases allow heat from the sun to enter the atmosphere
- the gases act as a ‘blanket’ and trap heat in the atmosphere
