• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7
  8. 8
  9. 9

Determine whether or not the intensity of light is affect on the rate of photosynthesis in a plant.

Extracts from this document...


GCSE Biology - Photosynthesis Coursework Aim The aim of my experiment is to determine whether or not the intensity of light is affect on the rate of photosynthesis in a plant. To do this, I placed a piece of elodea pondweed in varying light intensities, and observed the amount of oxygen being given off.. Introduction 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. All plants need light to do the process of photosynthesis, and so it is possible to say that without light, the plant will start to die. The light makes effect on the plant because, when the light falls on the chloroplasts in a leaf, it is trapped by the chlorophyll, which converts it into chemical reactions in the plant. The amount of sunlight from the sun, or in the case of bulb the light direct falls on the plant and more energy will be absorbed by the plant and more energy is available for the chemical reactions for more photosynthesis takes place in a given time. There are many factors, which affect the rate of photosynthesis, including light, temperature and carbon dioxide concentration. The chemical equation for photosynthesis can be expressed as: (Light) 6CO2 + 6H2O � C6H12O6 + 6O2 (in the presence of chlorophyll) Predictions I predicted that when the light will be increased and the rate of photosynthesis will be increase automatically. In the dark the plant will die, so in this case the process of photosynthesis does not occur. ...read more.


Move the bubbles, which have been collected at the bend in the tubing to the part of the tube with a scale. Find the length of the bubble collected. Repeat for all other readings, and then repeat all readings a second time to get an average result for each distance. Audus apparatus Using the described method, I found the following results: Results for main experiment Distance Light intensity length 1 length 2 average length (cm) (lux) (mm) (mm) (mm) 5 1015 3.5 3.5 3.5 10 945 3.5 3.5 3.5 12 770 4 3 3.5 14 639 3.5 3.5 3.5 16 500 3 3.5 3.25 18 395 3 3 3 20 310 2 3.5 2.75 25 208 1.5 2.5 1.75 30 149 1.5 1.5 1.5 35 110 1 1 1 40 80 0.5 1 0.75 45 55 0 0.5 0.25 Although, because I was using light intensity as my variable, I did not need to record the distances as well, I did, simply to use them as a marker for each result, so that I only had to record the light intensity once at the beginning and from then I just had to align the lamp at the correct distance each time. Analysis My graph was in the form of a best-fit curve. I drew it as a curve rather than a straight line because of the clear pattern of the points. This meant that the rate of photosynthesis increased as the light intensity increased. This was because photosynthesis is a reaction, which needs energy from light to work, so as the amount of energy available from light increased with the rise in light intensity, so did the amount of oxygen produced as a product of photosynthesis. ...read more.


Again if I were to carry out the experiment over a longer time period, it would have been necessary to add sodium hydrogen carbonate to the water to increase the carbon dioxide concentrations. The last inaccuracy, though a small one, was in the time keeping. The main problem here was in when to begin the minute. If for one reading, the minute 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. Overall, I felt that due to the small volumes of oxygen involved, my experiment was not as accurate as it could have been, however I believe it was accurate enough to support and justify my hypotheses. 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. The other obvious way of increasing the reliability of my results would be to take many repeat readings and find an average. 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)

    On section A of the graph showing an increase in light intensity, it shows as the light intensity is increasing, the rate of photosynthesis is also increasing. Point X is the optimum temperature. At section B the line is becoming constant.

  2. Marked by a teacher

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

    3 star(s)

    been turned on, to provide a light source for photosynthesis to take place. I shall start he experiment by turning the box exposing the pondweed to white light given from the ray box for one minute, while this is happening I shall keep a tally on the number of bubbles that are produced.

  1. Peer reviewed

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

    5 star(s)

    the temperature increases as the light intensity increases. A higher temperature would have made my results higher because it has an orthokinetic effect causing the speed of movement to rise until heat stroke and death intervenei. There is a particularly big increase of 6-8oC between readings 6 and 7.

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

    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.

  1. How does light intensity affect the rate of photosynthesis

    I will make sure that the temperature does not exceed 38?C because this will mean that the plant's enzymes will be denatured and no photosynthesis (or very little) will be able to take place. I will keep the amount of water the same by using a measuring cylinder to measure

  2. Experiment to Investigate the Effect of Temperature on the Rate of Photosynthesis in Elodea.

    One possible solution is to be put a black screen around the experiment. However this would be impractical as it would be impossible to take readings at eye level. The best solution would be to do the experiment alone in a room with no windows so the light intensity would be kept constant throughout the experiment.

  1. Investigating the effect of temperature on the rate of photosynthesis

    stand 2 To hold up and support the scale and also the test tube if it is placed in the water bath. Ruler (accurate to a millimetre) 1 To measure the distance from the lamp to the elodea, therefore light intensity will be more even.

  2. Investigate the affect of light colour (wavelength) on photosynthesis.

    But even though it is reflected some of it still gets absorbed as it has one of the highest energy rates out of all the colours in the visible spectrum. The rest of my results in the graph was quiet accurate.

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