When phytochrome detects more and more sunlight, the plant reaams its light-trapping molecules

As the phytochromes detect increasing sunlight, the plant readies its light-capturing molecules so it can photosynthesize and grow throughout the morning. After harvesting their morning light, plants use the rest of the day to build long chains of energy in the form of glucose polymers, like starch. The sun sets, and the day's work is done, though a plant is anything but inactive at night. In the absence of sunlight, they metabolize and grow, breaking down the starch from the previous day's energy harvest.