6- Nutrient Cycles

Question 0

What are the Global warming causes ?

Answer 0

CO2 conc increased:
•More fossil fuels+ petrol burnt
•Natural sinks destroyed-deforestation
•Trees burnt or decomposed

CH4 conc. increased:
• increase fossil fuel extraction
• increase cattle - farming

Question 1

Carbon cycle

Answer 1

1) CO2 taken in by plants-photosynthesis becomes C
2) C moved to consumers
3) Organisms die - saprobiotic microorganisms decompose
4) C returned to air- respiration
5) Deap Ocean+ bogs - no decomposers- C in dead organic matter converted to fossil fuels
6) Combustion of fossil fuels- CO2

Question 2

N-cycle

1) nitrogen fixation

Answer 2

N2 (atm) into NH3 - by bacteria ‘Rhizobium’

Non living proces: Lightening+Haber process

Question 3

N-cycle

2)Ammonification

Answer 3

N compounds from dead organisms + animal waste converted to NH3 compounds by saprobiotic microorganisms

Question 4

N-cycle

3)Nitrification

Answer 4

• NH3 into Nitrites (NO2)
• NO2 into Nitrates (NO3)
• By Nitrifying Bacteria

Question 5

N-cycle

4)Denitrification

Answer 5

• Denitrifying bacteria respire using NO3 in soil- produce N2 gas
• Under anaerobic conditions (waterlogged soil)

Question 6

Eutrophication

Answer 6

1) Nitrates leached from fertilised field into river/pond - increased growth of plant+algae
2) algae grow - block light from plants below
3) unable to photosynthesis- plants die
4) bacteria feed on dead plant matter
5) increase in bacteria - decrease O2 conc. - respiring
6) fish die - isn’t enough dissolved O2