28. Nutrient Cycles 1

Question 1

Nutrient

Answer 1

Elements that are essential for the development, maintenance, and reproduction of organisms

Question 2

Macronutrients

Answer 2

Elements required in large concentrations

e.g. carbon, hydrogen, oxygen, nitrogen, phosphorus

Question 3

Micronutrients

Answer 3

Elements required in small concentrations

e.g. Iron, magnesium, iodine, selenium, zinc

Question 4

What does the Redfield ratio describe

Answer 4

The elemental composition of earth’s biomass, Carbon:Nitrogen:Phosphorus

• 106C:16N:1P

Question 5

Nutrient Cycling

Answer 5

The transformation, movement, and reuse of nutrients within ecosystems

Question 6

Which nutrient is:
•Essential to energetics, genetics and structure of living systems (the main component of ATP, RNA, DNA, and PL molecules)
•Not very abundant in Biosphere
•No atmospheric reservoir
•Can be a limiting factor for aquatic primary production, but usually is not for terrestrial primary production

Answer 6

Phosphorus

Question 7

Phosphorus
-Where is most of it and how is it released

Answer 7

In mineral deposits and sediments

Usually released through weathering of rocks

Marine sediments > sedimentary rocks > soil > available for cycling

Question 8

Phosphorus
-How does it cycle

Answer 8

Plants take up P ions from soil or water, incorporate them into tissues

Animals gain Phosphate by eating plants or tissues of other animals

Animals eliminate P through urine

Question 9

Which nutrient:
•Important for structure and functioning of organisms
•A limiting factor of primary production in terrestrial and aquatic ecosystems
•One of earth’s biggest atmospheric reservoirs
•Microbes play a big role in cycle
•Much more complicated cycle than P

Answer 9

Nitrogen

Question 10

6 important forms of Nitrogen

Answer 10

NH3: Ammonia
NH4+: Ammonium

NO2-: Nitrite
NO3-: Nitrate
NO: Nitric Oxide

N2: Nitrogen gas

Question 11

5 transformations of Nitrogen

Answer 11

Fixation- converting atmospheric N into forms primary producers can use

Immobilization: mineral forms into organic forms

Mineralization: organic forms into mineral forms

Nitrification: ammonium into nitrite into nitrate

Denitrification: nitrate into nitrogen gas

Question 12

How is atmospheric N fixed, what does that mean?

Answer 12

Certain prokaryotes and lightning

N2 gas is reduced to NH3 (ammonia)

Question 13

Nitrogen
-how does it cycle
In organisms
In soil

Answer 13

In organisms:

Immobilized or assimilated inti primary producer tissues

Consumers eat primary producers or other organisms

Organisms die, N is released during decomposition by bacteria and fungi

Assimilation/immobilization> nitrification> denitrification

In soil:
Ammonification > nitrification > denitrification