Photosynthesis and the Environment. Section 3.5 Page 173. Processes a photosynthetic cell undergoes: Photosynthesis Photorespiration Cellular respiration. Photosynthetic rate. 6 CO 2 + 6 H 2 O + light energy C 6 H 12 O 6 + 6 O 2 How to measure rate experimentally?
6 CO2 + 6 H2O + light energy C6H12O6 + 6 O2
How to measure rate experimentally?
It is difficult to measure the rate because:
necessary to measure the net uptake of CO2 or net evolution of O2
Factors – can drastically alter the rate
As temperature increases, the rate of photorespiration increases more rapidly than the rate of photosynthesis (C3 plants)
slope is less (lower photosynthetic efficiency) at higher temperatures
CO2 uptake rate remains constant over all temperatures
Limiting factors to rate of photosynthesis:
O2 concentration also affects photosynthetic rate by competing with CO2 for rubisco
The photosynthetic efficiency is constant for a C4 plant, over all temperatures.
Photosynthesis & the Environment
Comparing photosynthesis and cellular respiration:
*note: Q5 refers to the energy profile of the respective electron transport chains. Refer to chart on pg. 181