Nutrient Cycles

Question 1

Carbon Cycle

Answer 1

Gaseous carbon is fixed in the process of photosynthesis and returned to the atmosphere in respiration, metabolism, decay and combustion. Carbon may remain locked up in biotic or abiotic systems for long periods of time e.g. in the wood of trees or in fossil fuels such as coal or oil

Question 2

Photosynthesis

Answer 2

Plants pull carbon dioxide out of the air through photosynthesis, products are glucose and oxygen

Question 3

Decomposition

Answer 3

Through the breakdown of organic materials carbon is returned to the atmosphere and soil

Question 4

Respiration

Answer 4

Animals produce carbon dioxide as a product of cellular respiration which is then released back into the atmosphere

Question 5

Combustion

Answer 5

Fossil fuels are burnt to release energy, carbon dioxide is a by-product of this reaction and is released into the atmosphere through this process

Question 6

Nitrogen Cycle

Answer 6

Nitrogen cycles between biotic and abiotic environments. Bacteria plays an important role in this transfer

Question 7

Nitrogen-fixing bacteria

Answer 7

Fix nitrogen gas by converting it into nitrogen compounds in soil

Question 8

Nitrifying Bacteria

Answer 8

Convert ammonia to nitrite and nitrite into nitrate

Question 9

Denitrifying Bacteria

Answer 9

Return fixed nitrogen back into the atmosphere by converting nitrates in soil into nitrogen gas

Question 10

Nitrogen Fixation

Answer 10

Converts atmospheric nitrogen to a soil form of nitrogen that is usable by plants, the majority of nitrogen fixation occurs when bacteria convert atmospheric nitrogen into ammonia

Question 11

Denitrification

Answer 11

Nitrates in soil are converted back into nitrogen gas which is released into the atmosphere

Question 12

Assimilation

Answer 12

Inorganic nitrogen compounds such as nitrates or ammonia are absorbed by plants and other organisms and used to form organic nitrogen compounds such as DNA, amino acids and proteins

Question 13

Nitrification

Answer 13

The breakdown of ammonia into nitrite and nitrite into nitrate by bacteria

Question 14

Ammonification

Answer 14

Organic nitrogen compounds in decomposing organism tissue and animal excretions are decomposed by various fungi and bacteria and ammonia is released back into the environment

Question 15

Hydrological (Water) Cycle

Answer 15

Collects, purifies and distributes the earth’s water

Question 16

Over Oceans

Answer 16

Evaporation exceeds precipitation. This results in a net land movement of water vapour of land

Question 17

On Land

Answer 17

Precipitation exceeds evaporation. Some precipitation exceeds evaporation, some precipitation gets locked up in snow and ice for varying lengths of time

Question 18

Condensation

Answer 18

Conversion of gaseous water vapour into liquid water

Question 19

Infiltration

Answer 19

Movement of water into soil

Question 20

Infiltration

Answer 20

Movement of water into soil

Question 21

Percolation

Answer 21

Downward flow of water through soil

Question 22

Transpiration

Answer 22

Release of water vapour into the air by plants

Question 23

Evaporation

Answer 23

Conversion of liquid water into gaseous water vapour