Where does photosynthesis occur?
Photosynthesis takes place mainly in the leaves, although it can occur in any cells that contain green chlorophyll. Leaves are adapted to make them very efficient at photosynthesis.
Leaves are broad, so as much light as possible can be absorbed. A leave is thin, so it is easy carbon dioxide to diffuse in to each of the cells in the centre of the leaf. It also contains green chlorophyll, in the chloroplasts, which absorbs the light energy. Leaves have veins to bring up water from the roots and carry food to other parts of the plant; a leaf as well has a stalk, or petiole, that holds the leaf up so it can absorb as much sunlight as possible.
Factors that affect photosynthesis
If a plant gets more light, carbon dioxide, water or a higher temperature, then it might be able to photosynthesise at a faster rate. However, the rate of photosynthesis will eventually reach a maximum because there is not enough of one of the factors needed, one of them becomes a limiting factors.
If a factor pumps extra carbon dioxide into a greenhouse, the rate of photosynthesis might increase so the crop will grow faster. However, if the light is not bright enough to allow the plants to use the carbon dioxide as quickly as it supplied, the light intensity would be the limiting factor.
Temperature is also a limiting factor; temperature affects the enzymes that control the chemical reactions of photosynthesis.
Prediction:
I predicted that the smaller the distance between the plant and the sauce of light, the greater would be the rate of photosynthesis. As out lined in the introduction, light is essential for the process of photosynthesis. Therefore the closer the light source is to the plant, the greater will be the intensity of the light and so the chlorophyll within the plant will be able to photosynthesise at a faster rate.
As discussed in the introduction light is one of the limiting factors in the process of photosynthesis. The existence of light is esational for this process, as the following equation shows:
LIGHT
Carbon Dioxide + Water Glucose + Oxygen
CHLOROPHYLL
The role of light within photosynthesis is too absorbed by chlorophyll. Chlorophyll is a green pigment present in the leafs of plants, once chlorophyll has absorbed light it is able to convert carbon dioxide and water into glucose and oxygen. Therefore, the more the light that is available to the green plant, the greater will be the rate of photosynthesis and so more glucose and oxygen will be formed.
Apparatus:
Breaker Test tube Lamp (light)
Test tube holder Elodea (pondweed) 6 cm Water 30ml
Goggles Stopwatch Thermometer
Ruler
Diagram:
Safety Procedure:
- Tie your scarf back
- Wear goggles
- Button up your sleeves
- Don’t spill water everywhere (just in case it their might be any socket around)
- Don’t touch the lamp when heated
Fair testing:
- Use the same amount of water
- Apply the same amount of time
- Same amount of plant type
- Same placement of sunlight
- Same length of plant
- Same temperature of water
- Use the same bulb in the lamp
Results:
Conclusion:
The purpose of the experiment was to find out if light affects the rate of photosynthesis, after carrying out this experiment; I have learnt that light does affect the rate of photosynthesis. The closer the light to the plant the more bubbles were produced which means that the rate of photosynthesis increased.
I predicted that the further the light to the plant the less bubbles will be produced this is because as the intensity of light is increased more light can be trapped by chlorophyll to produced glucose and oxygen. In this experiment the oxygen produced forms bubbles were counted to determine the rate of photosynthesis. The results that I got what I expected as they agreed with my prediction.
I think overall I obtained a good set of results. My process was well planned and it was repeated so that I could take an average of the results. This made sure that I do not end up with any anonymous results.
Evaluation:
For my experiment, I had to find out whether light affects the rate of photosynthesis. From my results I obtained, I found that light does affect photosynthesis. The results that I got where the ones that I predicted. The results that I obtained were good as they were as I excepted. However, there are ways in which I could have improved my results and made them more accurate. I could have improved my experiment by counting the bubbles more accurately buy letting two people counting instead of just one person counting.
The apparatus that I used was accurate, so I did not get any anonymous results. My range was good because I had measured every 10 cm but if had measured it every 5cm I would have get more accurate. I had enough results to figure out if light does affect the rate of photosynthesis. If I had wanted to, I could have obtained more results by getting closer distances e.g. every 5 cm, but I do not think it would make much of a difference to my conclusion.