A pondweed shoot is moved steadily closer to a lamp while temperature and everything else are kept the same. What happens to its rate of photosynthesis?

Explication

Light supplies the energy for the reaction, so delivering more of it each second lets the shoot work faster while light is what it is short of. The claim that the rise never stops is what fails, because sooner or later something else the reaction needs runs short, and bright laboratory lamps do not destroy the green pigment.