Nutrient Cycles

Question 1

what are the six elements involved in nutrient cycling?

Answer 1

• C, N, H, O, P, S
• take various chemical forms in the atmosphere, water, or earths surface and below
• geological processes contribute to cycling

Question 2

how much water is in the hydrosphere?

Answer 2

• 99.5% is non-potable saltwater
• 99% of the remaining 2.5% is underground or in ice
• less than 1% is available as freshwater

Question 3

what is the water/hydrologic cycle?

Answer 3

• E from sun warms water
• leads to evaporation (water to gas) and sublimation (ice to vapor) deposited in the atmosphere
• condensation creates clouds which return water via precipitation
• rain permeates underground and flows or is stored
• surface runoff is fresh water flowing from rain or ice that can move directly through streams and lakes into the ocean

Question 4

What is the carbon cycle?

Answer 4

• brings carbon to organisms, importance in macromolecule structure
• two interconnected sub cycles

Question 5

What is the biological carbon cycle?

Answer 5

• rapid exchange of carbon between autotrophs and heterotrophs using atmospheric CO2
• autotrophs use CO2 to create carbs used in respiration
• terrestrial autotrophs get C from the atmosphere
• marine autotrophs get the dissolved form carbonic acid
• heterotrophs get C by consuming autotrophs

Question 6

what is the biogeochemical carbon cycle?

Answer 6

• cycling of carbon through land, water and air by being held for lengthy periods in reservoirs
• limestone is a reservoir (calcium carbonate)
• soil, fossil fuels underground

Question 7

What is the nitrogen cycle?

Answer 7

• available to living organisms through free-living (cyanobacteria) and symbiotic (rhizobium) bacteria though N fixation
• human activity releases N though fossil fuel combustion and artificial fertilizers
• three steps

Question 8

What are the 3 steps of the nitrogen cycle?

Answer 8

• Ammonification: nitrogenous waste converted into ammonium by bacteria and fungi
• Nitrification: ammonium turns into nitrites by bacteria and then converted to nitrates
• Denitrification: Pseudomonas and Clostridium bacteria convert nitrates into N2 which reenters the atmosphere

Question 9

what is the phosphorous cycle?

Answer 9

• limited in aquatic ecosystems, P ion in terrestrial ecosystems
• runoff from human activity or rock moved from sediments over geological time
• moves through soil