• 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...

Introduction

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.

Middle

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.

Conclusion

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)

    Appendix 2 * Private area, as concentration is required on behalf of the participants a quiet room/area to be used * Chair and table, to allow subject to sit on and table for subjects arm and hand to lie flat * Pen, to note the times recorded * Instruction sheet,

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

    Out of the juvenile limpets counted on all three shores, were found on the lower shore and were found in the middle shore, with only found in the upper shore. This therefore indicates that juvenile limpets prefer to inhabit the lower and middle shores, where conditions are probably better suited to their survival.

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

    Barnacles may harm limpets they live on by weighing it down, or they could also help it by camouflaging it, so it is difficult to decide whether this is a parasitic of symbiotic relationship. The tidal levels are used to split the seashore into the four zones.

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

    Count 40 cress seeds and sprinkle randomly onto a Petri dish. 5. Open a freezer bag and check there are no holes in the bag. Flick it capturing as much air as possible in the bag 6. Quickly place a Petri dish inside the bag and hold the bag closed 7.

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

    on to complex IV by ubiquinone but no protons are pumped across the membrane. One ATP molecule is produced for every four protons that move across the membrane down the electrochemical gradient, that is, 2.5 ATPs are produced for every two electrons that pass down the electron transfer chain.

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

    It is about the pH found in the small intestine. Buffer solution 20cm3 To minimise small fluctuations in initial pH, and calibrate pH probe. Buffer solutions are resistant to small changes in pH and have a known pH. Bile Salts 5 cm3 for conical flask It emulsifies lipids.

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

    the following guidelines have to be followed: In order to protect the yeast, the operator will have to ensure that an excess is not used, and that only the necessary amount of yeast is used and no more. This makes sure that it is treated with respect as an organism.

  2. Flat periwinkle Investigation

    counted, the quadrat was flipped over on its side 180 degrees to the right ensuring that the right edge remained in contact wit the shore and the above method for counting the numbers of yellow, green and brown flat periwinkles was repeated, and the belt transect repeated of the lower

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