If you were to continuously increase light intensity, would the rate of photosynthesis increase indefinitely?

Question

I experimentally found out that when you increase the light intensity, that increases the rate of photosynethesis. What would happen if you were to keep increasing the intensity of light (without heating)? Would the rate of photosynethesis continue to increase?

Answer 1

No, definitely not. It would be limited by carbon dioxide. If you increase CO2 as well, then it would ultimately be limited by enzymatic capacity (primarily RuBP carboxylase activity, but many other enzymes as well). Furthermore, excess light that cannot be 'quenched' by non-chlorophyll pigments will damage the proteins in the chloroplast.

Answer 2

No. It is not possible on three reasons...

1. All matter has a maximum amount of energy it can store in terms of motion before it re-emits the energy. i.e. there is a physical limit to the point at which any matter can convert energy solely into mechanical energy.

2. All matter moves (i.e. heats up) when it absorbs energy. There is a limit to how much motion a molecule can have in a biological system before it destroys that system. i.e. it is impossible to continuously increase the intensity of light without burning an organism in the first place.

3. Even before an organism burns... photosynthesis is a bio-chemical process in which molecules absorb energy from light, those molecules move, and bio-chemical machines transfers that energy. These machines have limits on how fast they can transfer energy.

The later is known as the "light saturation point". Photosynthesis machinery in the cell breaks down on several points:

1. The matter reacting with the light reaches a point at which it is moving to fast for the machinery around it to collect its energy.

2. The machinery can't feed the chloroplast water faster enough, or the cell can't absort water fast enough.

3. The machinery can't operate fast enough. i.e. move water in and move oxygen out.

4. The oxygen being produced can not be expelled from the cell (and plant) fast enough and eventually becomes toxic.

Answer 3

Well, I think what would happen is that there would be a certain peak to the amount of photosysenthesis that a plant could do meaning there is only a certain amount of light that the plant would be able to absorb