ECCB 303 EXAM 4 QUESTIONS WITH VERIFIED
ACCURATE ANSWERS
Photosynthesis releases/creates... - answers - o2 and organic matter fuel
When did photosynthesis evolve? - answers - 2.8 bya
When did great oxidation occur/ evolve? - answers - 2.4-2.5 bya
Photosynthesis ____ o2 into the atmosphere while decomposition and respiration ___
o2. - answers - releases, consumes
If all of the om produced via photosynthesis is broken down via oxic respiration what
would the net change in atmospheric o2 be? - answers - zero (no change)
If some of the organic matter is burred/ not decomposed then atmospheric 02 _____ -
answers - increases
The great oxidation caused... - answers - increases in om burial, an increase in atm 02,
and a rise in complex life (animals)
Oxic respiration/ decomposition releases... - answers - water and co2 (and consumes
02)
Current level of atm 02 - answers - 21%
Charcoal - answers - char formed through pyrolysis-- (om+heat) creates carbon
(energy) dense organic matter.
Coal - answers - organic matter put under pressure over time -- creates carbon dense
om
How do they calculate change in atm 02 concentrations over time? - answers - often
use proxies (indirect evidence) to reconstruct 02 concentrations (coal, charcoal)
Combustion/ oxidative reaction - answers - fuel + o2 --> co2 + h20 (consumes 02)
When atm o2 concentration is below 15% then... - answers - fire is suppressed/ non
existent
What is the minimum atm o2 concentration for plants to ignite and fire to sustain itself? -
answers - 16%
, When is there a rapid increase in burn probability relative to atm o2 concentration? -
answers - between 18-20%
At what % of atm o2 concentration is fire sustained in wetter vegetation? - answers -
23%
When do very wet plants burn relative to o2 concentration? - answers - 30%
Relative to atm o2 concentrations when will saturated plants burn and not be able to
extinguish? - answers - above 35%
What and when is the burn window? - answers - the concentration of atm o2 where fire
can sustain itself. From 16-30%
At 16% atm o2 fire is - answers - constrained by ability to combust
At 30% atm o2 fire is - answers - constrained by fuel moisture availability
As o2 increases materials become more ____ - answers - flammable
As o2 increases, temp of ignition ____ - answers - decreases
As o2 increases, moisture of extinction ____ - answers - increases
As o2 increases, intensity ____ - answers - increases
Paleofire triangle - answers - climate, atm, vegetation
High o2 is ___ to living cells - answers - toxic
Concentration of po2 effects plant physiology - answers - has cascading effects on plant
community composition and fuel quantity/ type.
Photorespiration - answers - can be a big inefficiency in photosynthesis, certain plant
groups evolved to decrease photorespiration.
The main enzyme in calvin benson cycle - answers - rubp oxygenase-carboxylase
Why is photorespiration a pitfall? - answers - in photosynthesis rubp binds with co2 to
create glucose, though sometimes it binds with 02 instead and loses 3 fixed c and emits
co2 instead of forming glucose.
A positive feedback - answers - increases the effect of the change
A negative feedback - answers - decreased the effect of the change
ACCURATE ANSWERS
Photosynthesis releases/creates... - answers - o2 and organic matter fuel
When did photosynthesis evolve? - answers - 2.8 bya
When did great oxidation occur/ evolve? - answers - 2.4-2.5 bya
Photosynthesis ____ o2 into the atmosphere while decomposition and respiration ___
o2. - answers - releases, consumes
If all of the om produced via photosynthesis is broken down via oxic respiration what
would the net change in atmospheric o2 be? - answers - zero (no change)
If some of the organic matter is burred/ not decomposed then atmospheric 02 _____ -
answers - increases
The great oxidation caused... - answers - increases in om burial, an increase in atm 02,
and a rise in complex life (animals)
Oxic respiration/ decomposition releases... - answers - water and co2 (and consumes
02)
Current level of atm 02 - answers - 21%
Charcoal - answers - char formed through pyrolysis-- (om+heat) creates carbon
(energy) dense organic matter.
Coal - answers - organic matter put under pressure over time -- creates carbon dense
om
How do they calculate change in atm 02 concentrations over time? - answers - often
use proxies (indirect evidence) to reconstruct 02 concentrations (coal, charcoal)
Combustion/ oxidative reaction - answers - fuel + o2 --> co2 + h20 (consumes 02)
When atm o2 concentration is below 15% then... - answers - fire is suppressed/ non
existent
What is the minimum atm o2 concentration for plants to ignite and fire to sustain itself? -
answers - 16%
, When is there a rapid increase in burn probability relative to atm o2 concentration? -
answers - between 18-20%
At what % of atm o2 concentration is fire sustained in wetter vegetation? - answers -
23%
When do very wet plants burn relative to o2 concentration? - answers - 30%
Relative to atm o2 concentrations when will saturated plants burn and not be able to
extinguish? - answers - above 35%
What and when is the burn window? - answers - the concentration of atm o2 where fire
can sustain itself. From 16-30%
At 16% atm o2 fire is - answers - constrained by ability to combust
At 30% atm o2 fire is - answers - constrained by fuel moisture availability
As o2 increases materials become more ____ - answers - flammable
As o2 increases, temp of ignition ____ - answers - decreases
As o2 increases, moisture of extinction ____ - answers - increases
As o2 increases, intensity ____ - answers - increases
Paleofire triangle - answers - climate, atm, vegetation
High o2 is ___ to living cells - answers - toxic
Concentration of po2 effects plant physiology - answers - has cascading effects on plant
community composition and fuel quantity/ type.
Photorespiration - answers - can be a big inefficiency in photosynthesis, certain plant
groups evolved to decrease photorespiration.
The main enzyme in calvin benson cycle - answers - rubp oxygenase-carboxylase
Why is photorespiration a pitfall? - answers - in photosynthesis rubp binds with co2 to
create glucose, though sometimes it binds with 02 instead and loses 3 fixed c and emits
co2 instead of forming glucose.
A positive feedback - answers - increases the effect of the change
A negative feedback - answers - decreased the effect of the change
