PLSC 120 Midterm 2
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,Respiration
the controlled breakdown of sugar to release energy stored as sugar
What does respiration require?
glucose (sugar), oxygen, and ATP (energy)
What does respiration produce?
carbon dioxide, water, and ATP (energy)
Where does respiration occur?
mitochondria
Photorespiration
reaction that occurs when the rubisco attaches to oxygen (O2) instead of carbon dioxide
(CO2) during the Calvin Cycle
, Why is it bad for rubisco to attach to O2 instead of CO2?
the process becomes wasteful due to less sugar being produced but the same amount of
energy (if not more) is still being used
How often does photorespiration occur?
occurs regularly in most plants due to the stomatal pores closing (stressed/drought
stressed)
How does photorespiration affect the amount of CO2?
it decreases in the plant when the stomata is closed
How does photorespiration affect the amount of O2?
it increases due to the light reactions (O2 gets stuck between leaves - creates excess)
What plants regularly have photorespiration?
C3 plants
3 main types of photosynthesis pathways
C3, C4, and CAM
C4 and CAM plants
only plants that have Pep carboxylase in order to get carbon dioxide fixed (CO2 is fixed
producing a 4-carbon compound when it first enters the leaf ~ CO2 is then released either
where or when O2 is not present)
Exam Questions Verified
and Provided with A+
Graded Answers| Latest
Updated 2026
,Respiration
the controlled breakdown of sugar to release energy stored as sugar
What does respiration require?
glucose (sugar), oxygen, and ATP (energy)
What does respiration produce?
carbon dioxide, water, and ATP (energy)
Where does respiration occur?
mitochondria
Photorespiration
reaction that occurs when the rubisco attaches to oxygen (O2) instead of carbon dioxide
(CO2) during the Calvin Cycle
, Why is it bad for rubisco to attach to O2 instead of CO2?
the process becomes wasteful due to less sugar being produced but the same amount of
energy (if not more) is still being used
How often does photorespiration occur?
occurs regularly in most plants due to the stomatal pores closing (stressed/drought
stressed)
How does photorespiration affect the amount of CO2?
it decreases in the plant when the stomata is closed
How does photorespiration affect the amount of O2?
it increases due to the light reactions (O2 gets stuck between leaves - creates excess)
What plants regularly have photorespiration?
C3 plants
3 main types of photosynthesis pathways
C3, C4, and CAM
C4 and CAM plants
only plants that have Pep carboxylase in order to get carbon dioxide fixed (CO2 is fixed
producing a 4-carbon compound when it first enters the leaf ~ CO2 is then released either
where or when O2 is not present)
