• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
Page
  1. 1
    1
  2. 2
    2
  3. 3
    3
  4. 4
    4
  5. 5
    5
  6. 6
    6
  • Level: GCSE
  • Subject: Science
  • Document length: 2414 words

Rate of photosynthesis experiment

Extracts from this document...

Introduction

Stuart Green 11AK Rate of photosynthesis experiment Aim: To investigate whether wavelength affects the rate of photosynthesis. 6CO2 + 6H2O light energy & chlorophyll C6H12O6 + 6O2 Variables: Dependant Variable- Wavelength of light is to be the variable explored in this investigation. Changing the wavelength of the light source to the plant should vary the rate of photosynthesis. Light Wavelength (colour)- Light energy is absorbed by pigments in the leaf such as chlorophyll. Chlorophyll easily absorbs blue light, in the 400-450 nm range, and also easily absorbs red light in the 650-700 nm range. Chlorophyll does not absorb green light or yellow light effectively but tends to reflect them, decreasing the amount of light absorbed and decreasing the rate of photosynthesis. Why the rate of photosynthesis increases or decreased from the amount of light energy absorbed is what is being investigated in this experiment. The distance of the lamp, from the plant will be kept the same throughout the experiment. Dependant Variables: Carbon dioxide Concentration- CO2 concentration can affect the rate of photosynthesis since the more CO2 in the air, the more CO2 that can diffuse into the leaf. This variable can be fixed by adding a fixed amount of sodium hydrogen carbonate to the beaker and plant. The experiment should also be completed in one session so the plant doesn't absorb a significant percentage of the CO2. ...read more.

Middle

Our results were not exactly the same as the prediction graph, but several different things could cause this. Human error may have caused the results to be inaccurate. Some white light could have been used by the pondweed, causing the rate of photosynthesis to go up slightly. The heat being produced from the light may have also affected the rate of photosynthesis. Since temperature affects the movement of molecules and the reactions worked by enzymes, the heated molecules and enzymes may be the cause of the increasing rate of photosynthesis, because photosynthesis works using enzymes. This may account for why the number of bubbles being made was higher on the 3rd repeat, compared to the first repeat The photosynthetic rate increases when you are testing certain wavelengths; this means that plants can absorb certain wavelengths better than others. Our results show that orange light was the wavelength (630-700 nm) that had the highest rate of photosynthesis. We also found out that green light (500-600 nm) is the wavelength that has the lowest rate of photosynthesis. This is correct, according to our prediction graph. The only anomalies in our results are for the red wavelength, these are as low as the green results, which is not right. If you compare the results graph to the prediction graph, you can see that the red wavelength should be much higher. ...read more.

Conclusion

If during a repeated experiment, counting bubbles is still used, there is a smaller chance for human error when counting within a smaller time frame. If the capillary tube option was to be chosen, volume should be measured for a smaller time frame to reduce the overall time to complete the experiment. Also, during high rates of photosynthesis, it would still be difficult and impractical to measure the volume of oxygen produced for a long duration. Due to the nature and convenience of the experiment, it could be easily modified to investigate another variable of photosynthesis. Since sodium hydrogen carbonate (NaHCO3) is used to provide the pondweed with carbon dioxide. Performing the experiment with different volumes of NaHCO3 could vary the amount of CO2. The plant would be kept at a constant distance from the lamp and a constant volume of water would be added to the sodium hydrogen carbonate. Another experiment using almost identical apparatus would be to vary the intensity of the light the plant absorbs. Using a LVPSU (Low Voltage Power Supply Unit) you could vary the voltage going to the lamp, allowing you change the light intensity, like a dimmer switch. Since light intensity has already been identified as a variable of photosynthesis, it would be interesting to actually test it. The only way the measure the amount of light being produced by the lamp would be to use a Lux meter. Stuart Green 11AK Page 1 Of 3 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Green Plants as Organisms section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Green Plants as Organisms essays

  1. Marked by a teacher

    Investigate the relationship between wavelength of light and the rate of photosynthesis using pondweed.

    3 star(s)

    Once white light passes through chlorophyll, the blue and red colours disappear because the chlorophyll absorbs them, whereas the others pass straight through or are reflected. If a plant becomes deprived of red or blue light then photosynthesis will not take place correctly and will not produce all the necessary starch.

  2. How temperature affects the rate of photosynthesis.

    Then the clock will be started and the rate will be measured. * To gain higher temperatures like 30 oC, 50 oC and 70 oC, a kettle was used. This method can be improved upon by using a more accurate way to keep the temperature constant i.e.

  1. Experiment to Compare Stomata Density in Different Dicotyledonous

    coldish spring and thus would not need to conserve water so much and thus a relatively high stomata density would be predicted. However, this plant does not appear to have any waxy cuticle and evolution may have meant a reduction in stomata density to counteract this.

  2. Absorption Spectrum of Chlorophyll.

    of okra were virtually identical, as shown by Figures 7 and 10 respectively, any one of each can be selected for comparing the spectra of the two plants. Figure 11 compares the second extracts of spinach and okra. Both extracts were prepared with plant mass to acetone volume ratios of 1 g : 5 mL.

  1. The aim of my investigation was to determine how limiting factors would affect the ...

    sugars and amino acids from the cells manufacturing them. Water follows by osmosis. These materials then move into adjacent sieve elements by diffusion through plasmodesmata. The pressure created by osmosis drives the flow of materials through the sieve tubes. In "sink" tissue, the sugars and amino acids leave the sieve tubes by diffusion through plasmodesmata connecting the sieve elements to the cells of their destination.

  2. To investigate certain factors which affect the rate of photosynthesis in plants and how ...

    However, the rate of photosynthesis can only be increased by increasing the light intensity up to a certain point. Beyond that point, it will make no difference if you increase the light intensity further because one of the other factors which affect the rate of photosynthesis will be limiting it.

  1. To investigate a factor that affects the rate of photosynthesis

    11.) Proceed to the data analysis stage. Results: Distance (cm) Light Intensity (LUX) Bubbles per Minute Average bubbles/minute 1 2 3 0 (off scale) 240 249 251 246.7 5 11,000 201 222 214 212.3 10 5,800 183 185 188 185.3 15 3,570 154 152 158 154.7 20 2,320 128 118 124

  2. Find out what factors affect the rate of photosynthesis. Rate being the amount of ...

    And distance is very easy to measure. It is a more reliable variable that would most likely produce results that are not biased due to the fact that it can be easily manipulated. Prediction and hypothesis: The rate of photosynthesis will increase as the light intensity increases at a proportional rate.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work