• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

How does light intensity affect the rate of photosynthesis of Canadian Pondweed?

Extracts from this document...

Introduction

Step - By - Step Plan Firstly I will get all my equipment out and place it on my working place. Secondly I will turn out all the lights and pull down all the blinds (if there are any) so that I will be able to get maximum light intensity from my lamp to the pondweed and keep it a fair test as my pondweed is only getting the light from the lamp and from no where else. Then I will measure 10cm of pondweed and place it into my glass beaker and place my glass funnel over the pondweed as you can see in the following diagram: Next I will fill my glass beaker with water up to about half way then add my hydrogencarbonate indicator (to keep the amount of CO2 the same each time), after I have done that I will fill the glass beaker to the top with water, next I will get my straw and place it in the beaker filled with water and blow until it goes a yellow colour, this is about a blow for 5 seconds. After that I will get my test tube and fill it to its peak with water and put my thumb over it making sure I don't spill in water, I will carefully put it over the top of the funnel without losing any water (it is essential that you don't lose any water because if you do, each time you carry out the experiment there will be different amounts of water and it will not be a fair test) ...read more.

Middle

Prediction I predict that the closer the lamp is to pondweed the faster photosynthesis will take place because light is needed for the reaction and there will be more input energy. The rate of photosynthesis to the light intensity is inversely proportional so it will increase rapidly at first but will not increases so rapidly when the lamp gets closer to the pondweed. When the lamp gets close to the pondweed the lamp will be giving all the light (energy) that the pondweed will need to photosynthesise at its optimum speed. It cannot photosynthesise any faster 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 but if the light intensity is to high then it could bleach the chlorophyll and delay photosynthesis. The other limiting factors should be at their optimum or remain constant throughout the experiment and so should not affect the experiment. So overall I think that the most oxygen bubbles given off will be when the lamp is 10cm away from the pondweed because it is not to close and therefore wont bleach the chlorophyll and delay the rate of photosynthesis, I think it is the ideal distance. When the lamp is 20cm and 30cm away from the pondweed they will be relatively similar results and a difference of approximately 20 air bubbles. It will give off the least oxygen bubbles when the lamp is 40cm away from the pondweed because the further the lamp gets away from the pondweed the harder it is for the chlorophyll to absorb the light so it will take longer to photosynthesise. ...read more.

Conclusion

My line of best fit did not suit some of my results because I had anomalous results as a result of this. I may have had anomalous results because some of the factors were limiting by the time. Something or a factor was limiting. I would suggest that it was the temperature because it could have got too low and slowed the rate of photosynthesis or maybe the concentration of the carbon dioxide would explain the amount of anomalous results. The evidence is just about sufficient enough to support a firm conclusion because about half of the results are nearly accurate, although some are anomalous when drawing a line of best fit. Some results that were plotted are in one place and some scatter off on the graph which prove that they are anomalous and something was not accurate during the experiment such as a factor that was limiting. Evidence is sufficient as a clear pattern is discovered that this is because the rate of photosynthesis slows down and ultimately this supports this firm conclusion. The improvements I would make for further work is to allow my results to be even more accurate and fair and much more reliable, but trying to avoid anomalous results when obtaining evidence and analysing evidence. I would like to provide additional evidence for the conclusion by extending the results and making more justifications and using scientific knowledge for more key factors that could be tested which I would like to investigate and test on with this similar method. ...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

    An investigation into the effect of light intensity on the rate of photosynthesis of ...

    5 star(s)

    I do not think that it measured in the best way at the most appropriate times. The number of oxygen bubbles I counted has different sizes and different oxygen concentration. It can only show roughly the rate of photosynthesis. Control variable: temperature.

  2. How temperature affects the rate of photosynthesis.

    Same amount of time would be allowed for each piece of parent elodea from which the different lengths of elodea would be cut. These would be kept overnight for approximately 8 hours. Then, during the actual experiment, when the elodeas are introduced to a new light source, 2 minutes would

  1. Free essay

    Investigating the rate of photosynthesis of Canadian Pondweed

    I predict that as I increase the distance away from the lamp I will have less oxygen bubbles to count so as I decrease the distance from the lamp I will have more oxygen bubbles to count. Method: I am going to collect my equipment and I am going to

  2. whether or not the intensity of light would affect the rate of photosynthesis

    If my experiment were to be performed over a longer period of time, for instance 24 hours, I would add a fixed amount of Sodium hydrogen carbonate to the water, thus ensuring a large enough supply of carbon dioxide. Water availability - water is also required in the photosynthesis reaction,

  1. Test the prediction that the closer the lamp is to a piece of pondweed ...

    In this case, as long as the experiment is done over a short period of time, the amount of carbon dioxide used up by the plant will not be sufficient enough to cause the carbon dioxide concentration to become the limiting factor.

  2. Factors That Affect Photosynthesis.

    the pond weed using the plasticine. 5. Place a water-filled test tube upside down and over the funnel (see diagram). 6. Place the ruler so that the "0" measurement is aligned with the side of the beaker. (distance measured from side of beaker to edge of light bulb)

  1. Investigate a factor which may affect the rate of photosynthesis of Canadian pondweed.

    This will mean that the only variable in this experiment will be the light intensity, so making my experiment as accurate and fair as possible. Apparatus: * beaker * small syringe (capacity about 5ml) * glass funnel * plant irradiator * cut length of elodea, or Canadian pondweed * sodium

  2. Absorption Spectrum of Chlorophyll.

    Micropipette 12. 100 ml measuring cylinder 13. Aluminum foil 1. Milton Roy Spectronic 20D Spectrophotometer ( range: 400-700 nm, wavelength accuracy = ? 3 nm, absorbance accuracy = 0.5 percent transmittance) 2. Lab View (Interface designed by Al Giandomenico)

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