photosynthesis Flashcards
(12 cards)
Where are the light and dark reactions of photosynthesis located?
Light reaction takes place inside the thylakoid membranes. Dark reaction takes place in the stroma.
Light and dark reactions occur in chloroplasts.
What is the essential first step of transforming light energy into chemical energy?
Photons have to ‘collide’ with an atom to push out an electron of the most outer shell of the atom.
This process initiates the conversion of light energy.
What is photorespiration?
The loss of CO2; the light was used to separate CO2, draining from the Calvin cycles.
Photorespiration can reduce the efficiency of photosynthesis.
What process reduces the light use efficiency of C3 plants compared to C4 and CAM plants?
Photorespiration reduces the light use efficiency.
C4 and CAM plants have adaptations to minimize photorespiration.
What would happen to the rate of C3 photosynthesis if the concentration of oxygen in air was drastically reduced and replaced with nitrogen gas?
Rate of C3 photosynthesis would likely increase.
Lower oxygen concentrations reduce photorespiration.
What would be the effect on C4 photosynthesis if oxygen concentration was drastically reduced?
C4 photosynthesis would remain largely unaffected.
C4 plants are adapted to efficiently use CO2.
What aspects of prehistoric climate change is thought to have evoked the evolution of C4 photosynthesis?
The lack of CO2 concentration and cooling temperatures.
These conditions favored the evolution of C4 plants.
What are light and CO2 compensation points?
Light compensation point: light intensity at which photosynthesis equals respiration. CO2 compensation point: CO2 concentration at which photosynthesis equals respiration.
These points indicate the balance between photosynthesis and respiration.
How do the light and CO2 compensation points differ for C3 and C4 plants?
C3 plants have a higher CO2 compensation point than C4 plants.
This difference affects the efficiency of photosynthesis in varying conditions.
What is the name of the enzyme that permanently binds CO2 to organic matter?
Ribulose bisphosphate carboxylase oxygenase (RUBISCO).
RUBISCO is crucial for the Calvin cycle.
What is the name of the enzyme that binds atmospheric CO2 in C4 and CAM plants?
PEP carboxylase.
This enzyme initiates the fixation of CO2 in these plants.
How do C4 and CAM plants increase the concentration of CO2 inside cells and chloroplasts?
Both use PEP carboxylase to fix CO2 into organic acids. C4 plants store malate in bundle sheath cells. CAM plants capture CO2 at night.
These adaptations help them thrive in different environmental conditions.
