ECCB 303 EXAM 2 REVIEW QUESTIONS WITH
VERIFIED ACCURATE ANSWERS
Why is P essential for life? - Answers - P in ATP, DNA, RNA
Forms of P:Orthophosphates - Answers –
Geologic cycle - Answers –
Weathering - Answers - breakdown of primary minerals (rocks) over time
Runoff - Answers - weathered rock particles flow into oceans or streams
What determines weathering rates - Answers - rates increase with: temp, precip, slope,
vegetation
, Soil formation (property) - Answers - Climate + organisms/vegetation + topography +
parent material + Time
P sub-cycle within the larger geologic cycle - Answers - P can cycle for 100,000 years
before reaching the ocean; only small component enters the "fast" cycle - most remain
bound up in rocks
Terrestrial P: Four Inputs - Answers - Inorganic Fertilizer, Manure, Litter, Weathering
Terrestrial P: two main losses - Answers - Runoff, Leaching
Available P in the soil solution and what controls the amount available. - Answers -
Desorption, Dissolution, Mineralization
Organic P: mineralization vs immobilization, controls ( environmental and C : P ) -
Answers - :occurs in soil microbes
depend on:
- moisture & temperature
- C:P
> 300:1 = immobilization
< 200:1 = mineralization
sorbed P: Adsorption, what factors play a role in this process, speed, where it typically
occurs - Answers - (fast & reversible) - P from soil solution is bound to soil particles
sorbed P: Desorption, what factors play a role in this process, speed, where it typically
occurs - Answers - P from soil solution leave soil particles; increase in clay or Fe & Al
oxides = more desoprted P
Secondary P minerals: Precipitation - how pH is involved and what ions are involved,
speed - Answers - Process by which metal ions react w/ phosphate ions in the soil
solution to form minerals such as Al-, Fe- Ca-
slow, involves permanent charge into metal phosphates but they can release phosphate
upon dissolution
Secondary P minerals: Dissolution - how pH is involved and what ions are involved,
speed - Answers - release rate is slow - form of weathering of a secondary mineral
P uptake by plants: what forms are taken up by mycorrhizal fungi and how do they help
with P uptake, important in terrestrial? - Answers - 80% of plants form mycorrhizal
symbiosis
Fungi take up: HPO4-2 and H2PO4
Plant gives fungi sugars in return
VERIFIED ACCURATE ANSWERS
Why is P essential for life? - Answers - P in ATP, DNA, RNA
Forms of P:Orthophosphates - Answers –
Geologic cycle - Answers –
Weathering - Answers - breakdown of primary minerals (rocks) over time
Runoff - Answers - weathered rock particles flow into oceans or streams
What determines weathering rates - Answers - rates increase with: temp, precip, slope,
vegetation
, Soil formation (property) - Answers - Climate + organisms/vegetation + topography +
parent material + Time
P sub-cycle within the larger geologic cycle - Answers - P can cycle for 100,000 years
before reaching the ocean; only small component enters the "fast" cycle - most remain
bound up in rocks
Terrestrial P: Four Inputs - Answers - Inorganic Fertilizer, Manure, Litter, Weathering
Terrestrial P: two main losses - Answers - Runoff, Leaching
Available P in the soil solution and what controls the amount available. - Answers -
Desorption, Dissolution, Mineralization
Organic P: mineralization vs immobilization, controls ( environmental and C : P ) -
Answers - :occurs in soil microbes
depend on:
- moisture & temperature
- C:P
> 300:1 = immobilization
< 200:1 = mineralization
sorbed P: Adsorption, what factors play a role in this process, speed, where it typically
occurs - Answers - (fast & reversible) - P from soil solution is bound to soil particles
sorbed P: Desorption, what factors play a role in this process, speed, where it typically
occurs - Answers - P from soil solution leave soil particles; increase in clay or Fe & Al
oxides = more desoprted P
Secondary P minerals: Precipitation - how pH is involved and what ions are involved,
speed - Answers - Process by which metal ions react w/ phosphate ions in the soil
solution to form minerals such as Al-, Fe- Ca-
slow, involves permanent charge into metal phosphates but they can release phosphate
upon dissolution
Secondary P minerals: Dissolution - how pH is involved and what ions are involved,
speed - Answers - release rate is slow - form of weathering of a secondary mineral
P uptake by plants: what forms are taken up by mycorrhizal fungi and how do they help
with P uptake, important in terrestrial? - Answers - 80% of plants form mycorrhizal
symbiosis
Fungi take up: HPO4-2 and H2PO4
Plant gives fungi sugars in return
