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

To investigate the hill reaction

Extracts from this document...


Name: Kern Pemberton Date: 7th November, 2008 Lab#: 5 Aim: To investigate the hill reaction Theory: Photosynthesis is a process carried out in plants, in the photosynthetic organ which is the leaf. CO2 + H2O --> (CH2O)n + O2 A plant takes in CO2 and H2O and absorbs sunlight in order for photosynthesis to take place. These reactants then travel to the chloroplasts in the palisade cells of the leaf, where the actual process takes place. In photosynthesis there are two reactions; the light dependant reaction and the light independent reaction. The light dependant reaction takes place in thylakoids of the grana of the chloroplasts whereas the light independat takes place in the stroma. The thylakoids of the chloroplasts contain pigments which can be divided into accessory and primary pigments. These pigments form light harvesting clusters which can then be divided into different photosystems, those being photosystem I and photosystem ll. In photosystem I, the accessory pigments trap energy from the sunlight and funnel it to the primary pigment or chlorophyll a. This then becomes excited and releases an electron which is accepted by an electron acceptor. The electron then moves through a series of electron carriers arranged in order of their redox potentials. Meanwhile, the photosystem is said to be unstable as a result of chlorophyll a losing an electron. ...read more.


7. 0.5 ml of the chloroplast suspension was placed in a test tube followed by 5 ml of DCPIP. This was then placed in the dark and the aluminium foil was not removed. 8. The time taken for a colour change from blue to green was then observed and recorded. Diagram: Diagram 1.0 shows setup of apparatus to check time taken for colour changes in tubes. Results: Tube Time taken for colour change from blue to colourless/min 10 cm away from light source 1.53 100 cm away from light source 15.55 Isolation in medium only No change Tube in dark No change Table shows different times for colour changes to be observed. Discussion: Photosystem ll as mentioned in the theory, NADPH and 02. In this process light strikes both photosystem l and ll, the energy is funneled down by the accessory pigments to the primary pigment and this causes the primary pigment from PS l and PS ll to release an electron. The electron from PS l is accepted by an electron acceptor and then passes through a series of electron carriers arranged in their redox potentials. The electron then is accepted by another electron acceptor and then neutralizes the H+ in the splitting of water. H2O - 2H+ + 2e- + O2 This H is then picked up by NADP and forms NAPH. ...read more.


This is because the isolation medium contained no chlorophyll for photosynthesis to take place. However, when the tube with the chloroplast suspension which includes the isolation medium was placed in a tube, but in the dark, there was no colour change either. This shows that light is needed for photosynthesis to take place. Precautions: * The amount of chloroplast suspension and DCPIP placed in the tube was standardized. * The distance of the light source from the tube was ensured with a centimeter ruler. * The salt/ice water was used to preserve the samples so that no biological activity would have taken place before the experiment had taken place. * The aluminium foil was used so that no light would have entered the sample before the experiment started. Limitations: * The DCPIP was blue in colour and the chloroplast suspension was blue in colour. Therefore, the colour change was not from blue to colourless and this could have affected one's observation of the colour change. Sources of error: * The experiment was done during the day and sunlight entering the room could have affected the results in some way of it had any exposure to the test tubes. Improvements: * It could have been ensured that the room was completely dark or sunlight was not reaching the tubes in any way. * The amount of light could have been reduced by putting layers of tissue paper between the light and the test tube to produce a range of light intensities. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Energy, Respiration & the Environment 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 AS and A Level Energy, Respiration & the Environment essays

  1. Marked by a teacher

    Fighter Pilot A Statistical Analysis of Reaction time and its Correlation with Dominant ...

    5 star(s)

    32 Overall average 21 Overall average 28 Table 2 Data from preliminary field work; reaction time of ten subjects shown in seconds Dominant Non-Dominant Test results (s) Test results (s) Subject Try Try Try Average Subject Try Try Try Average 1 2 3 1 2 3 1 0.197 0.169 0.156

  2. Investigate the effect of bile salt concentration on the digestion of milk by the ...

    The reason I think this information is relatively accurate is almost all is posted by reputable companies and all is in accordance with the OCR endorsed sources. However, information from the internet should be placed under some scrutiny as again the reader cannot for certain know who posted the information so some may actually be wrongly informing.

  1. An investigation into the distribution of adult and juvenile limpets on a rocky shoreline.

    Lower shore Middle shore Upper shore Chi squared number The chi squared value for the results collected on juvenile limpets is 419.93. This value is 406.11 above the value given for 0.1 % significance showing that juvenile limpets are actively choosing to inhabit the lower and middle shores over the upper shores.

  2. A Comparative Study of the Density of Patella Vulgata (Common Limpets) in the Optimum ...

    it also aids the dispersal of eggs, therefore affecting the number of young born. It circulates oxygen, carbon dioxide and water vapour, affecting photosynthesis and respiration of macro-algae, which limpets feed on.), light (affects how much photosynthesis macro-algae are able to carry out), temperature (affects desiccation rate), oxygen and carbon

  1. Investigating the effects of different lead chloride concentrations on the growth of cress seedlings

    This causes K+ channel proteins in the plasma membrane to open so K+ can diffuse into the cell down an electrochemical gradient towards the negatively charged region. The extra K+ ions in the cell lower the solute potential, and therefore the water potential.

  2. Weed study. Dandelions - descrption and characteristics. Investigation to dandelion distribution.

    certain organism, which will affect the amount of dandelions, which are present. The season, as I implemented my investigation in September, the light intensity has decreased, which may have effected how the dandelion photosynthesis. All these factors will be considered when I write my conclusion.

  1. Investigating how prolonged exposure to its optimum temperature affects the respiration of yeast.

    * Conical Flask. * 100 cm� Beaker. * Stirring Rod. * Thermometer. * Delivery Tube. Kettle Possibility of scalding, especially with just recently boiled water. Conductor of the experiment / colleagues - While there are only two risks, it is imperative that the risks are minimised. Therefore, the experiment has to be conducted with utmost care, and

  2. How ATP is produced in both the chloroplast and mitochondria.

    Figure 1 shows a mitochondrial ETC. It consists of three protein complexes - complex I is the dehydrogenase complex, III the b-c1 complex and IV the cytochrome oxidase complex`. Each contains multiple oxidation-reduction centres. In I the main redox couple is NAD+/NADH, in III it is Fe3+/Fe2+, and in IV it is Cu2+/Cu+.

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