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

An experiment to investigate the effect of Light intensity on the rate of photosynthesis.

Extracts from this document...

Introduction

AN EXPERIMENT TO INVESTIGATE THE EFFECT OF LIGHT INTENSITY ON THE RATE OF PHOTOSYNTHESIS. Prediction As the light intensity increases, so the rate of photosynthesis will increase. The rate of photosynthesis should be directly proportional to the intensity of light directed, given that the other possible variables remain constant. There should be an optimum temperature above and below which the rate of photosynthesis will be lower. I expect that this temperature will be 30oC and therefore, this is the temperature at which the experiment will be conducted. I chose this temperature because the 25oC used in the trial did not produce the optimum conditions for production of oxygen. The oxygen is formed by the combining of carbon dioxide and water to make glucose and oxygen. The glucose is needed by the plant as a source of energy and the oxygen is just a waste product of this process. Carbon Dioxide + Water Glucose + Oxygen 6C02 + 6H20 C6H12O6 + 602 (Nuffield co-ordinated Sciences Biology) This equation relies on the unlikely occurrence of twelve different molecules all reacting in the same place at the same time and in the right order. There are in fact, two different stages of photosynthesis, one light stage and one dark stage. This means that it is much more likely that the reaction will take place as it is broken down into simpler stages. All of the molecules do not, therefore, have to be in the same place at the same time. ...read more.

Middle

Check that the temperature has not changed from 30oC and add hot or cold water to the beaker if necessary to adjust. 6. Measure the volume of gas produced in 2 minutes. 7. Repeat twice more to ensure an accurate result and to eliminate errors, then take the mean readings of the three. 8. Move the light to a distance of 148cm and repeat steps 1 - 7 above. 9. Move the light to distances of 191cm, 230cm, and 330cm and repeat steps 1 - 7 above for each distance. Table of Results Distance of light from plant (cm) Length of bubble of gas produced (mm) Average Length of bubble (mm) 1 2 3 135 33 35 39 36 148 27 31 30 29 165 23 24 21 23 191 12 10 12 11 230 10 8 11 10 330 8 8 6 7 To find out what the light intensity was at each of the distances I used the formulae shown above the table. This is the factor I compared the total distance of the oxygen bubble to. Distance from plant (cm) Rate of Photosynthesis-length of O2 bubble (mm/s) Light 1 intensity d2 (lux) Light intensity scaled up by factor a of 100,000 (lux) 135 36 0.000055 5.5 148 29 0.000046 4.6 165 23 0.000038 3.8 191 11 0.000027 2.7 230 10 0.000019 1.9 330 7 0.0000092 0.92 Conclusion The graph shows that there is a direct correlation between the light intensity and the amount of oxygen produced through photosynthesis in a plant. ...read more.

Conclusion

To solve this, the apparatus could be placed in a thermostatically controlled water bath. This would control the ambient temperature around the apparatus and therefore the temperature of the oxygen bubble To extend the experiment, I could use different plants to see if there is a correlation between the light intensity and the rate of photosynthesis for other plants including land plants. I could also aerate the water around the plant so there is a constant supply of carbon dioxide in the water for the plant to use during photosynthesis. Aerating the water would also prevent any oxygen being lost by dissolving into the water. To keep the same amount of minerals available for each test, I would also have to change the water each time. The plant needs the minerals to grow and to produce the chloroplasts needed for photosynthesis. The main mineral needed for this is magnesium so this would have to be very carefully controlled in order to keep all of the variables constant. I could also measure the amount of gas produced more accurately by measuring the mass of the gas produced. To do this, I would have to measure the mass of the apparatus before the experiment and after the experiment. The water inside the apparatus could not be changed between weighing, as this would change the results. The mass would have to be measured to a very high accuracy because the mass of a gas is so small. This would have to be used on a land plant, as it would be very difficult to measure the correct mass of a water plant. Water is constantly moving through the plant and so the mass would be constantly changing. ...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. Experiment to investigate the effect of Carbon Dioxide on the Rate of Photosynthesis

    From this information a graph can be drawn of rate of photosynthesis against concentration or carbon dioxide. Significantly, the results match the prediction that was given. This indicates that the theory that the prediction was based on was correct. Thus one can draw conclusions from the findings and relate these to scientific knowledge.

  2. How does light intensity affect the rate of photosynthesis

    I could also wait for the lamp to cool down after each measurement to minimise the temperature difference in measurements. I could also let the beaker cool off from each measurement for the same reason. An idea to make my graph more presentable and easier to interpret I could use

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

    Cyclic photophosphorylation only involves photosystem I. Light is absorbed by photosystem I and is passed to chlorophyll a (P700). An electron in the chlorophyll a molecule is excited to a higher energy level and is emitted from the chlorophyll molecule.

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

    A graph of the rate of photosynthesis at different concentrations of carbon dioxide has the same shape as that for different light intensities. At low concentrations of carbon dioxide, the supply of carbon dioxide is the rate-limiting factor. At higher concentrations of carbon dioxide, other factors are rate limiting, such as light intensity or temperature.

  1. What is the effect on the rate of respiration of yeast cells with glucose ...

    Safety goggles should be worn to protect the eyes from any possible harm. Aprons should also be worn and any bags put underneath desks so that they are out of the way, as someone could trip up over it. To ensure that the equipment is safe the experiment should be

  2. How temperature affects the rate of photosynthesis.

    Pull the syringe back slowly and draw water into the potometer until a constant line of water is formed. No air bubbles should be present and the cut end of the elodea should be always under water. Draw water until some of it enters the syringe.

  1. Investigating the effect of Light Intensity on Elodea.

    The length needs to be the same in each experiment so that light intensity is the only variable. Length of Elodea used in preliminary exp. - 20cm. * Cut the ends of the pondweed so that the opening is fresh, not dying away (as done with flowers).

  2. Three separate experiments which are to be carried out to investigate a plant's unique ...

    Counting the stomata on a Laurel leaf: In this experiment, I will attempt to find out the number of stomata on a laurel leaf's surface. Apparatus needed: One laurel leaf, clear nail varnish, senior microscope, glass slide, glass slide cover.

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