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AS and A Level: Energy, Respiration & the Environment

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447 AS and A Level Energy, Respiration & the Environment essays

  • Marked by Teachers essays 13
  • Peer Reviewed essays 15
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  1. Marked by a teacher

    The Ways in Which Organisms Use ATP

    4 star(s)

    A thorough and well structured report, which could be improved by:
    1) The addition of references
    2 Some brief explanations of key terms, processes and molecule roles
    3)Attention to formatting

    • Essay length: 1102 words
    • Submitted: 23/12/2011
    • Marked by teacher: (?) Kerry jackson 07/02/2012
  2. Marked by a teacher

    Biology coursework investigation: Comparing the length of ivy leaves (Hedera helix) in areas of greater illumination and shade

    4 star(s)

    ****A very good A-level experiment report, in which the key elements of a scientific paper are clearly attempted. To improve:
    1)Give a more detailed explanation of the biology behind…

    • Essay length: 4139 words
    • Submitted: 19/04/2011
    • Marked by teacher: (?) kerry Jackson 27/03/2012
  3. Marked by a teacher

    How is ATP produced and used in living organisms?

    4 star(s)

    Overall this is a good solid essay, clearly written and covering the major points. Towards the end it is less well written and looks a little rushed. The last two…

    • Essay length: 1325 words
    • Submitted: 10/09/2003
    • Marked by teacher: (?) Rebecca Lewis 24/09/2012
  4. Marked by a teacher

    AS Edexcel Biology - Aim: To investigate the effect of caffeine on the heart rate of Daphnia (water fleas).

    3 star(s)

    Quite a good overall account of the investigation but analysis of the results could have been more critical, and plotting of wrong graph is a major error.…

    • Essay length: 1082 words
    • Submitted: 13/02/2012
    • Marked by teacher: (?) Adam Roberts 11/12/1999
  5. Marked by a teacher

    The Role of the Respiratory and Circulatory Systems in the Provision of Oxygen and the Removal of Carbon Dioxide from the Body

    3 star(s)

    Some relevant information is included and the report addresses the role of the circulatory and respiratory systems in transport of oxygen and carbon dioxide, but far too much irrelevant information…

    • Essay length: 3019 words
    • Submitted: 14/01/2012
    • Marked by teacher: (?) Kerry jackson 07/02/2012
  6. Marked by a teacher

    How can we prioritise species for conservation?

    3 star(s)

    This report gives an overview of the reasons for conserving threatened species and how species can be selected for conservation. The structure is clear, but some sections are inadequately…

    • Essay length: 2388 words
    • Submitted: 14/01/2012
    • Marked by teacher: (?) Kerry jackson 07/02/2012
  7. Marked by a teacher

    Describe the role of energy in the body and the physiology of three named body systems in relation to energy metabolism

    3 star(s)

    The essay sets out to explain the role of energy in the human body - where the body obtains its energy supply from and what activities the energy is required…

    • Essay length: 2470 words
    • Submitted: 27/03/2011
    • Marked by teacher: (?) Ross Robertson 01/03/2013
  8. Marked by a teacher

    Biological Importance of Water

    3 star(s)

    ***

    The student has thought of most of the main points that should be included in this essay, but some are explained better than others. In most cases he…

    • Essay length: 941 words
    • Submitted: 28/02/2009
    • Marked by teacher: (?) Rebecca Lewis 24/09/2012
  9. Marked by a teacher

    ATP or Adenosine Triphosphate.

    3 star(s)

    ***

    There are lots of good points made in this essay, but there are also several quite fundamental misunderstandings, some of which are a little worrying. This essay would…

    • Essay length: 1313 words
    • Submitted: 15/03/2005
    • Marked by teacher: (?) Rebecca Lewis 24/09/2012
  10. Marked by a teacher

    Adenosine Triphosphate.

    3 star(s)

    ***

    There are lots of good points made in this essay, but there are also several quite fundamental misunderstandings, some of which are a little worrying. This essay would…

    • Essay length: 735 words
    • Submitted: 31/10/2003
    • Marked by teacher: (?) Rebecca Lewis 24/09/2012
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Things to remember when planning an A level experiment

  1. 1 Write your procedure/method as a series of numbered steps. This helps the reader to follow your procedure easily. Describe precisely how you plan to control all control variables. Explain why it is necessary to control these variables in terms of how they could impact on the results.
  2. 2 Include all volumes, weights, concentrations, times, temperatures etc ensuring that you specify SI units. The method needs to provide all relevant details, so that another A-level student could complete the experiment to obtain data.
  3. 3 Use the results of a trial experiment to explain your reasons for selecting specific equipment, volumes, times, independent variable ranges, concentrations, pH, etc.
  4. 4 Clearly state the statistics test you plan to use to analyse your data. To look for:
    a) Statistically significant relationships between the independent and dependent variables use Spearman’s rank.
    b) Statistically significant differences between two categories use t-tests for normally distributed data or a Mann Witney U for non-normally distributed data.
  5. 5 Ensure that you state the range you plan to investigate and the number of times you will repeat the experiment clearly. Make sure that you include an independent variable range of at least 7 if you plan to use Spearman’s rank (eg. 7 different temperatures or concentrations) or at least 6 repeats if you plan to use the Mann Witney U test for difference.

Helpful hints for ecological sampling

  1. 1 Systematic sampling along a transect is used to investigate species distribution along an environmental gradient. For example if you are investigating the effect of water depth on seaweed growth as you move further up a rocky shore, you would use a transect and sample systematically at specified intervals (eg 2 Metres).
  2. 2 Random sampling is used to investigate the abundance of species in two distinct areas. For example the growth of daisies in mowed and un-mowed areas of a park.
  3. 3 Quadrats are used for both systematic and random sampling to ensure that species are counted within a defined and controlled area.
  4. 4 Random coordinates are generated and used to sample un-biased areas of each plot during random sampling.
  5. 5 The data from systematic sampling is analysed for correlation using Spearman’s rank. The data from random sampling is analysed for significant difference using a t-test (if the data is normally distributed) or Manny Whitney U.

Respiration and ATP facts

  1. 1 Energy cannot be produced, it is transferred. Conversely ATP is produced when energy is transferred from glucose during respiration.
  2. 2 The energy stored in ATP is released after ATP is hydrolysed to ADP and Pi. Some energy is required for ATP hydrolysis, but when bonds form between Pi and water more energy is released than is required for the initial hydrolysis of ATP, i.e. the reaction is exergonic.
  3. 3 Glycolysis is the first step in both aerobic and anaerobic respiration. Glycolysis occurs in the cell cytoplasm and yields 2 ATP molecules by substrate level phosphorylation. Glycolysis is the only source of ATP in anaerobic respiration.
  4. 4 The link reaction, Kreb’s cycle and electron transfer stages of respiration occur in the mitochondria and depend on oxygen as a terminal electron acceptor. In the absence of oxygen these aerobic stages cannot take place.
  5. 5 In aerobic respiration the majority of ATP is produced as a consequence of electron transfer. Each reduced NAD molecule donates electrons to the electron transfer chain, and 3 ATP molecules are generated as a consequence. Each reduced FAD molecule that donates electrons leads to the generation of 2 ATP molecules. During glycolysis, the link reaction and the Kreb’s cycle a total of 10 reduced NAD and 2 reduced FAD are produced, leading to the generation of approximately 34 ATP molecules following electron transfer.

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