# Relationship between light intensity and the rate of photosynthesis

### BBC Bitesize - GCSE Biology (Single Science) - Photosynthesis - Edexcel - Revision 4

Revise photosynthesis with BBC Bitesize GCSE Biology. Graph demonstrating the relationship between light intensity and the rate of photosynthesis. KELATION BETWEEN LIGHT INTENSITY AND RATE OF. PHOTOSYNTHESIS OF LOBLOLLY PINE. AND CERTAIN HARDWOODS. Paul J. Kramer and John P. You can measure it with a light meter or just use distance from the light source as your variable. You can measure photosynthetic rate by counting oxygen.

Photosynthesis is controlled by enzymeswhich become denatured if the temperature is too high. As a result, the rate of photosynthesis reaches its maximum at an optimum temperature, then decreases. The maximum rate is determined by the other factors involved.

### BBC Bitesize - GCSE Combined Science - What happens during photosynthesis? - OCR 21C - Revision 5

Graph showing rate of photosynthesis and temperature Light intensity Investigating light intensity Light provides the energy needed for photosynthesis. Increasing the light intensity increases the rate of photosynthesis, provided plenty of carbon dioxide and water are available. Graph showing rate of photosynthesis and light intensity The role of light in photosynthesis can be investigated in several ways. In this experiment, a light is moved further from a photosynthesising plant to vary the light intensity the plant receives.

### As light intensity increases, what happens to the rate of photosynthesis? | Socratic

The further the light moves from the plant, the fewer oxygen bubbles are produced by photosynthesis. A light source positioned at a distance from a photosynthesising plant The intensity of light at different distances from a light source can be described by the inverse square law.

This states that the intensity of light is inversely proportional to the square of the distance from the source. In practical terms, this means that when the light is moved twice as far from the plant it will receive a quarter of the energy. Calculating light intensity Light intensity can be calculated using this formula.

First boil and cool distilled water to drive off dissolved CO2 so that you can control this. Obviously, I have not answered your question for dealing with the amount of water.

This actually is a more difficult thing to test because measuring the oxygen produced is harder when you are not using an aquatic plant.

If you just want numbers to plug into your model, take a look at this scientific paper: The water content is on the X bottom axis, while the Y up-and-down axis shows the rate of photosynthesis measured by how much CO2 the plant took up. Note that the 2 different species responded differently.

You can also see that there is a lot of variation, but you can use the average photosynthetic rate for each water level. The scientists also looked at the effect of CO2 and temperature.

Temperature would depend on light intensity, so you could use that in your model. At low light intensities, light is a limiting factor for photosynthesis.

Required Practical: Investigate the effect of light intensity on rate of photosynthesis

The rate of photosynthesis to the light intensity is inversely proportional so it will increase rapidly at first the levels off until it reaches its optimum speed. It cannot photosynthesize any faster after that because there is only a certain number of chloroplasts containing a limiting amount of chlorophyll and this can only absorb a certain amount of light which is called the light saturation point.

## Photosynthesis

Since there are many steps involved in photosynthesis and each step has its limiting factor, it can not be this simple. You can see that you definitely need water for the photosynthesis to go on. But we say that water availability is only indirectly limiting photosynthesis because for the C4 plants, carbon dioxide is often the limiting factor. See Pathways of Photosynthesis for some detailed information. You can check these papers for references and I'm sorry that they are not online for easy availability.