Nutrient Cycles

Question 1

How do free-living bacteria undergo nitrogen fixation?

Answer 1

• reduce nitrogen to ammonia
• to make amino acids
• when they die they release nitrogen rich compounds

Question 2

How do mutualistic bacteria undergo nitrogen fixation?

Answer 2

• reduce nitrogen to ammonia
• In nodules of legumous plants
• get carbohydrates from the plant
• give amino acids to the plant

Question 3

What is the process of ammonification?

Answer 3

• decomposers feed on dead material
• they release ammonia
• Ammonia makes ammonium ions in the soil
• Nitrogen is returned to the soil

Question 4

What is the process of nitrification?

Answer 4

• nitrifying bacteria convert ammonium ions to nitrite ions by oxidation
• then convert nitrite ions to nitrate ions by oxidation

Question 5

What is dentrification?

Answer 5

In anaerobic conditions

-dentrifying bacteria convert nitrates to nitrogen gas

Question 6

Explain the nitrogen cycle

Answer 6

-Atmospheric nitrogen is converted to nitrogen compounds in plants via nitrogen fixing
-nitrogen compounds in plants is either:
-consumed by animals
- converted to ammonium compounds via ammonification
– nitrogen in animals is converted to ammonium compounds via
Ammonification
- ammonium is converted to nitrites then to nitrates by nitrification
-The nitrates are absorbed by plants in aerobic conditions
- the nitrates are converted to nitrogen gas by dentrification in anaerobic conditions

Question 7

Explain the process of the carbon cycle?

Answer 7

• carbon From water and air is passed to the plants via photosynthesis
• primary consumers eat plants therefore carbon is passed to them
• when consumers die, decomposers digest them and so get carbon compounds
• if detritus is not digested, they’re turned to fossil fuels
• when fossil fuels are burnt, they release carbon into the air ( combustion)

Question 8

What are the consequences of increased carbon gases in the atmosphere?

Answer 8

• melt polar ice caps : extinction of organisms
• rise in sea levels: thermal expansion of oceans, reduce biodiversity, salt effect crops
• increased temperature and decrease rainfall: failed crops, xerophytes would grow, alter distribution of organisms
• increased rainfall and intensify storms: alter distribution of organisms
• life cycles of insects and pests would be altered: disease could spread

Question 9

Possible benefits of increased carbon gases in the atmosphere?

Answer 9

• fill reservoirs
• grow crops in places where couldn’t before
• increase photosynthesis: harvest twice a year possibly

Question 10

What is nitrogen fixation?

Answer 10

Turning nitrogen gas to nitrogen containing compounds