• 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
  10. 10
  11. 11
  12. 12
  13. 13
  14. 14

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

Extracts from this document...


Investigation to find out how light intensity effects the rate of photosynthesis Contents * Introduction * Aim * Hypothesis * Variables * Precaution * Fair Testing * Apparatus * Method * Diagram for Method * Results * Analysis of Results and Graphs * Conclusion * Evaluation * Errors, limitations and Improvements Introduction Flowering plants, like all living organisms, need a supply of food. They need it as a source of energy in respiration and they need it as raw material for growth and repair. Animals and most micro- organisms get their food in an organic form: they eat products from other organisms (such as fruit and eggs) or, nowadays, the organic substances made in laboratories and factories. Animals and the microorganisms that do this are called consumers. Due to the flowering plants can make their own organic food from simple inorganic substances and an outside source of energy, they are called producers. Once the producers have made their food they use it in the same way as the consumers do as a source of energy and as raw material for growth and repair Photosynthesis The simple inorganic substances from which flowering plants make their food are carbon dioxide (CO2) and water (H2O). These contain no energy that a flowering plant can use an outside source of energy is needed to combine them into a compound that the plant can use as food. The source of energy is sunlight; the food compound that is made up the simple sugar, glucose (C6H12O6), and the waste product that is left photosynthesis, is shown in an equation as: Carbon dioxide + Water Glucose + Oxygen 6CO2 + 6H2O C6H12O6 + 6O2 Light energy is trapped by photosynthesis and converted into chemical energy in compound glucose. Carbon Dioxide Carbon dioxide is a gas which is present in air only in small amounts about 0.04% of air is carbon dioxide. ...read more.


* The leaves chosen for the practical must not be variegated or yellow. They must be green. Fair Testing By applying fair testing to a practical, a candidate can be fair in obtaining his or her results. The fair testing I am going to apply to my practical is: - * I will set up the apparatus exactly as shown in my method. * In the effect of light intensity on the rate of photosynthesis experiment, I will use a ruler to measure the distance of the lamp from the jar. * I will count the number of bubbles produced by marking dots on the paper as the bubbles are produced. Then I will count them to write how many bubbles are produced. * I will repeat my experiment twice to improve their validity and reliability. Apparatus 1. Pondweed 2. A beaker of water 3. 10cm3 of sodium hydrocarbonate 4. Funnel 5. Bench Lamp 6. Stop Watch Method 1. Fill a beaker with tap water and add 5cm3 saturated sodium hydrocarbonate solution. 2. Select a pondweed shoot about 2-4cm long 3. Set up apparatus as shown in diagram 4. Place a bench lamp about 8cm away from the beaker, switch on and start the timer 5. Record the number of bubbles produced in ten minutes. 6. Repeat step 1-5, moving the bench lamp to 20cm away from the beaker. Diagram for Method Results The effect of light intensity on the rate of photosynthesis. Lamp at 8cm away from the beaker Time (minutes) Number of oxygen bubbles 1 34 2 56 3 78 4 93 5 108 6 139 7 145 8 158 9 189 10 196 Lamp at 20cm away from the beaker Time (minutes) Number of oxygen bubbles 1 12 2 19 3 33 4 58 5 65 6 74 7 91 8 95 9 99 10 106 Graph for test 1 and 2 Graph for the rate of photosynthesis Analysis of Results and Graphs To work out the gradient I shall use the formula of dy/dx. ...read more.


Using translucent color filters in front the lamps could vary this. Since light wavelength has already been identified as a variable of photosynthesis, it would be interesting to actually test it. The only problem of this experiment is that there is no way to define or "measure" the color of light. Wavelength would be a solution but this cannot be measured with available equipment. We only have a general idea of how to class colors. Because of this, the colored light experiment should not be taken as seriously as light intensity or carbon dioxide. Errors, Limitations and Improvements Like all experiments there is always room for improvement and this one is no exception. My main limitation was time. If there had been enough time I could have carried out the same experiments but in various different ways, another problem that occurred with my experiment was that the temperature had been fluctuating whilst the lamp was at 8cm from the beaker. I could have done the experiment more than once but this would have been a waste of time as I felt my present results were good enough. I could have used a couple of different types of pondweed to see if this made a difference to the results. If I was to do this experiment again then this is the method that I would use to improve it. * Collect a beaker of 100ml. Fill up to 100ml * Collect a fresh piece of Elodea (Canadian pondweed) about 5cm3 long * Attach the pondweed to two paper clips, so that it is weighed down. Then place the Elodea into the water * Take the funnel and place it over the Elodea upside down * Measure 10cm intervals up to 1m away from the lamp * Start stopwatch when the light is turned on * Count how many bubbles are produced in 2 minutes * And repeat the same experiment 3 times. Hopefully using this method will make a better experiment and produce better primary results, so that secondary data doesn't have to be used. Apart from some problems the experiment went quite well. ...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

Here's what a teacher thought of this essay

4 star(s)

This is a very well written practical. There are a few errors but they are minor. It is well laid out with a good example of how to write a conclusion.

The writer could improve in some areas such as variables and scientific terminology.


Marked by teacher Sam Morran 15/05/2013

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

    Biology Lab Report. Does light intensity affect the rate of photosynthesis?

    4 star(s)

    1. The length of the pondweed is insufficient. Therefore, the amount of oxygen released is not sufficient. 2. The time allocated for the experiment to be done is not sufficient. The amount of oxygen released is not sufficient to change the colour of the sodium bicarbonate indicator. 3.

  2. Peer reviewed

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

    5 star(s)

    obtain a full range of results within a conceivable amount of time, ensuring that I am able to get a complete analysis of the effect of light intensity on the speed of woodlice. I am aware that the highest light intensities that I employ may result in no further increase

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

    oxygen produced in a minute, and there for finding the rate of photosynthesis * The amount of pondweed - is kept the same because the increase in pondweed the higher the rate of photosynthesis, so keep it constant I used the same pondweed through out the experiment.

  2. Experiment to investigate the effect of Carbon Dioxide on the Rate of Photosynthesis

    When the rate of photosynthesis stops increasing as much this will be because of saturation and the fact that the reaction is running at its maximum or because there are other limiting factors limiting the rate of the reaction. To measure the amount of carbon dioxide, the substrate sodium hydrogen

  1. How does the variable, light Intensity affect the rate of photosynthesis?

    Which I shown on the graph below. Distance from lamp (cm) Volume of Oxygen produced (mm3) @ 3% HCO3 Average 20 83 40 81 60 49 80 40 90 24 100 18 Graph 2 Analysis: From the graphs, you can clearly see that there is a trend in the results.

  2. Im going to investigate the affect of light on the amount of Pleurococcus. ...

    The rose diagram shows that the side with the most light on average which is the south side has the least Pleurococcus.

  1. An Investigation To Show What Different Factors Affect The Growth & Germination Of Cress ...

    Green leaves Nitrogen 18 3.5 6 Light green leaves Sulphur 10 3.5 6 Light green leaves Magnesium 14 3.5 6 Green leaves Friday Normal 15 4 6 Green leaves Nitrogen 18 3.5 6 Yellow stems, green leaves Sulphur 12 3.5 6 Yellow stems, green leaves Magnesium 16 4 6 Yellow

  2. Do different coloured wavelengths of light affect the rate of photosynthesis in Canadian Pond ...

    But I was incorrect about my prediction that the red filter would increase the rate of photosynthesis as it was close to the infrared end of the light wavelength spectrum, in fact the red filter produced the second lowest number of oxygen bubbles.

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