• 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?

Extracts from this document...


AUTHORS NOTE; PLEASE USE BUT CHECK THROUGH BEFORE USE TO MAKE SURE ALL MATERIAL IS RELEVENT TO YOUR EXPERIMENT. THIS IS A 8,8,8,6 LEVEL WORK BUT NEEDS A GRAPH OF THE RESULTS AND A PAGE WITH DIGRAMS OF APPARTUS SETUP ON. ALSO NEEDS A GRAPH SHOWING LIGHT INTENSITY AND RATE OF PHOTOSYNTHESIS. By Robbie Latchford Isleworth and Syon School For Boys HOW DOES LIGHT INTENSITY AFFECT THE RATE OF PHOTOSYNTHESIS? Aim The aim of my experiment is to find out if the intensity of light affects the rate if photosynthesis in Canadian Pondweed (Elodea). I will measure the number of bubbles produced in two minutes. I will change the light intensity on the Elodea to be the input variable. I will do this by moving a bench lamp closer or further away from the plant. I will add sodium hydro carbonate to the water to aid the photosynthesis. Sodium hydro carbonate produces Carbon Dioxide. Background Knowledge Photosynthesis occurs only in the presence of light, and takes place in the chloroplasts of green plant cells. Photosynthesis can be defined as the production of simple sugars from carbon dioxide and water causing the release of sugar and oxygen. The chemical equation for photosynthesis can be expressed as: Carbon Dioxide + Water Glucose + Oxygen 6CO + 6H O C H O + 6O The fact that all plants need light in order to photosynthesise has been proven many times in experiments, and so it is possible to say that without light, the plant would die. ...read more.


Place 500ml of H O into a beaker. Add 1 spatula of Sodium Hydro Carbonate to the H O. 2. Set up the boiling tube, glass funnel, and Elodea as shown in diagram. 3. Set up bench lamp with the cover on and position 10cm from beaker. 4. Turn on the lamp and start the stopwatch. Count the number of bubbles produced in 2 minutes. 5. Record the data in the results table, including the light intensity (in lux) 6. Repeat process with light meter at 20cm, 30cm, 40cm etc. 7. Repeat to 100cm and the repeat whole experiment another two times. Record all data collected in the table. Fair Test * Use the same Elodea * Keep the CO levels constant * Ensure that the bench lamp is the only light source * Use the same lamp and bulb throughout * Use the same amount of H O Safety * Keep other away from the experiment * Keep the experiment away from the edge of the table * Clear up spilt water Results Distance From Lamp Light Intensity Bubbles Produced In Two Minutes 1st Try 2nd Try 3rd Try Average 10cm 2390 184 179 182 182 20cm 1100 153 157 150 153 30cm 650 147 142 145 145 40cm 440 143 131 136 137 50cm 300 127 124 121 124 60cm 220 120 117 111 116 70cm 170 107 103 105 105 80cm 150 95 94 93 94 90cm 140 86 ...read more.


As I mentioned in my planning, carbon dioxide concentration could have been an error in the experiment, however, I feel that due to the short period of time taken, there is very little chance that the concentration would ever have been so low as to have become the limiting factor. The last inaccuracy, though a small one, was in the time keeping. The main problem here was in when to begin the two minutes. If for one reading, the two minutes was started just after one bubble had been produced, and in another reading it was just before, this could have had a negative effect on the accuracy of my results. I therefore ensured that in each case I started the stopwatch just after a bubble had been produced, thus heightening the accuracy. Improvements could have been made as I have stated, mainly by simply increasing the time taken. However, due to practical time constraints in taking the readings for my investigation, and some consequential problems relating to time extension, I could not in fact make these adjustments. To extend my enquiries into the rate of photosynthesis, I could perhaps try to link in some of the other limiting factors to the same experiment, as well as investigating them in their own right. It could also be interesting to explore the effects of coloured lights on the rate of photosynthesis, which could lead to the question of whether or not other types of light, such as fluorescent lights or halogen lights, would have a different effect on the rate of photosynthesis. ...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

    Investigation to find out how light intensity effects the rate of photosynthesis

    4 star(s)

    The meaning of dy is the difference in the y-axis and the meaning of dx is the difference in the x-axis. By using the gradient I shall also be enabled to work out he rate of reaction. The gradient for the experiment when the lamp is 8cm away from the

  2. Marked by a teacher

    Light Intensity and Photosynthesis.

    4 star(s)

    I estimate that the error could have been up to 0.5cm and I will find the percentage error for the largest and smallest reading using this estimate: Percentage error = possible inaccuracy total reading % error distance 10 5cm 1 50cm It is clear to see that the percentage error is much less for the larger distances.

  1. Marked by a teacher

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

    3 star(s)

    Analysis The bar chart represents results collected in the second experiment because these were more accurate than the first lot. I discovered that the white light produced the most bubbles on both experiments. The white light carried photosynthesis out at the fastest rate, producing the greatest amount of oxygen bubbles.

  2. Peer reviewed

    An Investigation into the Effects that Different Light Intensities have on the Speed of ...

    5 star(s)

    However, there was some variability in my results explained by both the thigmokinesis response of woodlice and by the simple fact that all woodlice are different. These anomalous results are reflected in the error bars on my graph. I also found that my results could show more of a curve shaped graph, as well as a linear regression.

  1. Photosynthesis. The aim of my experiment was to determine whether or not the intensity ...

    however, I feel that due to the short period of time taken, there is very little chance that the concentration would ever have been so low as to have become the limiting factor.

  2. The aim of my experiment is to find out how light intensity affects the ...

    How Carbon dioxide affects photosynthesis: As carbon dioxide concentration increases, the rate of photosynthesis increases. At high concentrations, the rate of photosynthesis begins to level out due to factors not related to carbon dioxide concentration. One reason might be that some of the enzymes of photosynthesis are working at their maximum rate.

  1. Investigate the effect of light intensity and the colour of light on the rate ...

    However it does not easily absorb green or yellow light, rather it reflects them, decreasing the amount of light absorbed, and therefore the rate of photosynthesis. This can easily be controlled, simply by using the same lamp throughout the experiment.

  2. How does light intensity affect the rate of photosynthesis

    I have also decided to let the plant settle down for two minutes after I have put the Sodium Hydrogen Carbonate in and put the light on, so that it can have time to start photosynthesising, so I can collect the maximum amount of oxygen that I can for each measurement to make them more reliable.

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