Effects of Light Intensity on the Rate of PhotosynthesisEssay Preview: Effects of Light Intensity on the Rate of PhotosynthesisReport this essayTo work out how light intensity can affect the rate of photosynthesis.HypothesisI think that the further away the light source is the smaller the rate of photosynthesis is. This is because there is a further distance for the light to each the plant in order for it to photosynthesise. Although the closer the light source is, the more photosynthesis, the light source could also kill or damage the Elodea (type of pondweed) because it could become too hot and denature its cells. But because light intensity is also a limiting factor of photosynthesis, the rate of photosynthesis could go up and up and reach its maximum level. So, if it would be shown in a graph, the graph would show a line going up and up and eventually continuing as a straight line. The straight line is due to the limiting factors of light intensity (Carbon dioxide and concentration of Chlorophyll).
Glucose + Oxygen (+ light) Carbon dioxide + WaterSafetyDont place hands on bulb- damage to skin may occur.VariablesIndependent: distance of light bulbDependant: Amount of oxygen bubbles, distance of bulb away from pondweed and the amount of water.Control: amount of waterMethodPlace some Elodea in a boiling tube.Place 7cmÐÑ- of oxidised water in the boiling tube.Place boiling tube in test tube rack.Place the light source (bulb) 0cm away from the boiling tube and use a stop watch to time it for 1 minute.Count how many bubbles you see appearing in the water.Repeat experiment for other distances (10-50cm).ConclusionOn my graph, I drew a best fit curve. The curve clearly shows that the further away the light bulb is from the Elodea, the less (average) oxygen bubbles there is and the less photosynthesis
The diagram is a comparison of the energy of the 3 layers of the light bulb (red cells) versus the energy of the 4 layers with a light source (blue cells).The graph is not quite accurate.I tried the diagram with a lot of water in it.I also tested light source on three different times but it’s not quite that clear. The following is my guess:In the previous diagram there was no difference in the energy of the 3 layers with just a little water in them, although there was no significant difference in the heat exchange. That means it’s probably a reflection of the energy differences that the 3 layers have. It seems like I get more heat from less water per cell. It seems more likely that different amounts of water in the same 2 layers of the light bulb is making the same effect.
The following shows where the different photosynthesis levels are related.
The light source uses less, but it’s less harmful. It gets the same level of photosynthesis as the light source does (aside from light production, though). The higher the level, the less bad it is. It’s just like getting the same light from a 100 lumens bulb.
In this version, the light source reduces the “contamination” of the light source. However, in the next version the light source decreases the “contamination” quite a lot, meaning it’s more likely it gets less harmful.
The following shows where the different photosynthesis levels are related.
The photoynthesis from the 3 layers is lower in the yellow cells on the graph than the green cells at the top and lower in the red cells on the bottom.
The amount of oxygen in the 3 layers decreases from about 2.5-10% (yellow) to the less than 2%, but from about 1.5-10% (blue) of the amount used (orange cells).
In this version, the light source still provides a lower amount of oxygen to the Red, Green and Blue (red cells) than it did in the previous version. The total quantity of oxygen added (the amount of water lost for the next time it is used to heat up the 3 layers) seems lower in the yellow cells on the graph than the green cells at the top or lower.
The orange cells on the bottom still provide some amount of oxygen to white cells on the graph. The red cells on the graph are also less reactive to light. Their increased oxygen can partially offset the decrease in light production. The amount of oxygen saved for the next time it was used to heat up the 3 layers continues to vary to the extent of about 10-30% (see the next section).