The rate of photosynthesis can be monitored as a function of either CO2 uptake or O2 production.
Since organisms that photosynthesise (such as plants) also undergo respiration (to have usable energy from the food they just made through photosynthesis), the relationship between the amount of photosynthesis and the amount of respiration that takes place at any time can be analysed.
Photosynthesis taken alone is the gross photosynthesis taking place. After accounting for any respiration that is using up the products of photosynthesis, extra products of photosynthesis amount to the net photosynthesis.
net photosynthesis = gross photosynthesis – respiration
The point at which photosynthesis and respiration are taking place at the same rate is called…