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

Hill Reaction Lab

Extracts from this document...


Wednesday 18th of Mach 2009 IB Photosynthesis Experiment Aim of the Experiment: To investigate the effect of light intensity on the rate of photosynthesis. A relation is sought for that would, if existent, allow estimation for untested values of light intensity. Research Question: How does controlled light intensity affect the rate of increase in the excess of oxygen created by the elodea plant undergoing photosynthesis? Hypothesis: Many plants use the process of synthesis to convert light energy into chemical energy (carbohydrates). The waste product, useful for other life forms is oxygen, a product of photolysis. Carbon dioxide, water and chlorophyll and light are essential for this reaction. The scarcity of any of these affects the rate of reaction. By controlling light intensity one should limit the rate of reaction of photosynthesis and hence the excess oxygen produced should have a varying rate linked to the light intensity. We therefore need to control at least one of the other controlling factors of photosynthesis and in this lab it will be temperature. For this experiment the variables are the following: Independent variable: light intensity, changed by varying the light's distance to the elodea complex. ...read more.


A best-fit equation was formulated and a log relationship was chosen because that is the one that arise in a light intensity against rate of reaction graph. However the equation in this situation only gives us a rough estimation of what the speed will be only on an exact same kind of lab. It can be seen, even with only the calculated values, that after about 100 kJm-2 the rate of increase stabilizes , meaning that it is very near to its optimum value and that another factor than light must be changed for a maximized optimum. In Blackman and Wilson's "Physiological and ecological studies in the analysis of plant environment" they found that "the net assimilation rate during the season of active growth is linearly related to the logarithm of the light intensity". This is why a logarithm best-fit equation was produced, which smoothly fits the graph. In addition, a logarithmic relationship was to be expected as the way the light intensity varied with distance meant that it increased in an exponential way. Conclusion The results of this lab do show a relationship between light intensity and output of excess oxygen theoretically due to photosynthesis in the elodea plant. ...read more.


They have two advantages, firstly is that they are not subject to human raw observation but more importantly use the lux SI light unit, a much more concise way of measuring light intensity(energy per square meter cannot be converted into lumen but provides a good estimation nonetheless). Another issue which might seem trivial but actually has some impact is the orientation of the elodea. As air naturally rises in water there is a high probability that air accumulated at the top of the syringe and did not cause the bubble(hence the measurements) to change and reflect the real rate of reaction. To solve this one would simply have to turn the syringe upside down with the cut end of the leaf upwards (where the gas easily exits). Finally it would be a good idea to test the gas for its content in O2 as this is one of the best indicators for the rate of photosynthesis. This is a bit simpler than it may seem as but using the physical and chemical proprieties of gases one can estimate quite accurately the percentage by adding pyrogallol (absorbs oxygen and therefore changes the volume of a gas) and observing the results. The same is true for testing CO2 presence with potassium hydroxide. Additionally, both of these elements are relatively easy to be obtained. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our International Baccalaureate Biology 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 International Baccalaureate Biology essays

  1. Investigating an enzyme-controlled reaction: catalase and hydrogen peroxide concentration

    so that a greater quantity of substrate molecules could be broken down into products. However past a certain point, which in my investigation was at an enzyme concentration of 25 potato discs, there were many free active sites but insufficient substrate molecules to occupy them.

  2. Biology Lab Report-Osmosis

    It was relatively hard and rigid but not as much so as the chip immersed in distilled water. 0.2M NaCl solution:- The potato chip that was immersed in 0.2M NaCl solution decreased in length but it increased in mass. It was not as hard or inflexible as the potato chip in 0.1M solution.

  1. Biology HL IA - Photosynthesis of elodea lab report

    Whole mechanism of it was filled with carbonate water using syringe by removing the plunger of syringe. At first trial, the lamp was positioned 10 cm away from the beaker containing the plant. The photosynthesis was let to take place for 10 minutes, using a stop-watch.

  2. Lion King-The Ecological study

    In order to acquire a dead body of an herbivore, carnivore.Iit is quite hard and takes long and hard process of fighting between them in order to get a result of the fight as a dead body.

  1. The effect of light intensity on cyclosis on Elodea leaf cells

    by mistaking another chloroplast for the original while measuring, leading to a different measurement. Breathing onto the specimen alters the CO2 concentration and so alters the result. Uneven number of recordings were made due to bad time management. Systematic errors: A systematic error in the experiment came in the controlled

  2. Ecology Open Investigation Does the geographic location affect the biotic and abiotic ...

    Graph 2.1 compares the average result of turbidity, oxygen levels, pH levels in 2004, 2005 and 2009 of 18 Mile Swamp. Unlike BL, the turbidity of 18MS has increased over the years. The increase of turbidity may be the result of increase algae and reeds.

  1. Biology Industrial Melanism of Peppered Moth Lab

    Data Processing Overview I have chosen to use the format of tables to display the data of the percentages of melanic and light-coloured moths left after each trial/generation on different coloured "tree bark". I have chosen the format of tables because it provides a clear understanding of the collected data

  2. Sleep is a normal part of human life. Investigate the neurobiological basis of normal ...

    These changes cause urine to be more concentrated during sleep. 3. Alimentary activity. In a person with normal digestive function, gastric acid secretion is reduced during sleep. In those with an active ulcer, gastric acid secretion is actually increased and swallowing occurs less frequently.

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