Photosynthesis in C4 and CAM plants Flashcards
Rubisco is an
enzyme required in the light-independent stage of photosynthesis.
What is the full name of RuBisCO?
Ribulose 1,5, Bisphosphate Carboxylase - Oxygenase.
What does Rubisco do?
RuBisCO is the enzyme that kicks off the Calvin Cycle in photosynthesis by fixing carbon dioxide (CO₂). (Basically, it helps turn atmospheric CO₂ into organic compounds that plants can use to grow.)
The difference between C4 and CAM plants is
CAM plants undertake photosynthesis where the light-independent stage is separated over time whereas in C4 plants it is separated over space.
Rubisco has a lower affinity to bind to O2 over CO2 when
there is low O2 concentration or when temperatures are normal or cool.
What is a key characteristic of C3 plants in relation to photorespiration?
C3 plants have no mechanism to minimise photorespiration.
How do C4 plants minimise photorespiration?
C4 plants minimise photorespiration by separating carbon fixation and the Calvin cycle by space.
How do CAM plants adapt to hot, arid environments?
CAM plants separate carbon fixation and the Calvin cycle by time.
[- They open their stomata at night to fix CO₂ into organic acids and store it.
- During the day, with stomata closed, they release CO₂ for the Calvin cycle—conserving water and reducing photorespiration.]
Why is photorespiration harmful to plants?
because RuBisCO binds to oxygen instead of carbon dioxide, preventing the Calvin cycle from producing glucose. This wastes energy and reduces the plant’s photosynthetic efficiency, especially in hot or dry conditions.
