• 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)

    A t-Test will be carried out to determine statistically if there is a significant difference between the means or whether they occurred by chance. A calculation of 95% confidence limits/intervals (CIs) will also be carried out as a 95% CI of the mean indicates how confident we can be that

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

    Therefore l can reject the null hypothesis and determine that adult and juvenile limpets are occupying different shore heights. Only a small number of juvenile limpets choose to inhabit the upper shore in comparison to the middle and lower shore.

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

    Figure 8. Energy pyramid with four trophic levels in a marine environment At the First Trophic Level in the sea, algae absorb nutrients through their fronds from the surrounding water and create energy by the fixation of carbon in the process of photosynthesis.

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

    oxidation of one molecule of palmitate and 31 molecules from the oxidation of one molecule of glucose. The process is about 40% efficient - i.e. 40% of the available free energy can be stored in the ATP molecules during oxidative phosphorylation Chloroplasts: The reduced carbon energy source that is oxidised by the mitochondria (such as carbohydrate)

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

    This in turn stops plant growth. Lead also inhibits the plant growth regulators. Gibberellins are plant growth regulators that promote stem elongation and seed germination. They can be found in many parts of the plants, in particular it is concentrated in areas such as young leaves, seeds and stems where growth is important.

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

    100cm3 - As required to alkaline milk to pH 8.5. This alkaline solution is added to the milk to mimic the alkaline pH of the small intestine. It has a pH around 9 and so it is not very alkaline.

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

    100 cm� Measuring Cylinder 2 To be inverted and filled with water, so that the Carbon Dioxide released through respiration can float up the water, and cause some space at the top, meaning that the amount of Carbon Dioxide can be measured in cm�.

  2. Flat periwinkle Investigation

    Flat periwinkles were identified by their teardrop shaped operculum, flattened spire and rounded almost spherical shape. Each quadrat was thoroughly checked, ensuring that both the top and bottom of each piece of seaweed was thoroughly examined. Background reading (Charles, 1982)

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