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AS and A Level: Energy, Respiration & the Environment

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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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  1. Zonation on the Rocky Shore at Starfish Bay.

    The dependent variables to be measured are the species on the rocky shore and their distribution. The independent variables influence the dependent variables and consequently affect data collection. These are the abiotic factors - the tidal variation, time of exposure above water, salinity of water, wave activity, temperature etc. The controlled variables are the method and time available for data collection. The method adopted for this investigation is to set up a transect on the rocky shore at Starfish Bay, i.e.

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  2. Molecules and Energy Sysytems.

    when a monomer - that being a nutrient in its most simplest form e.g. monosaccharide in CHO, amino acid in protein and a fatty acid molecule in lipids, essentially a 'building block' forming a larger more complex dimer (two monomers) or a polymer (three or more monomers). Fats (lipids) are another basic nutrient found in the body that performs many functions and plays several roles within. The two main functions of lipids in the body are insulation and protection. Fat cells (adipocytes)

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  3. Natural resources and renewable energy.

    How are modern societies dependable on natural resources? 2. How can the insight of the physical nature and origins of natural resources lay foundations of a sustainable society? 3. How can the web natural resources weave between all aspects of human society and the physical earth lay foundations for a sustainable society? * Food Resources: - Modern societies depend on food for survival, survival through growth and reproduction from chemical energy obtained from what is consumed. Food resources can be derived form croplands, rangelands and oceanic fisheries.

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  4. VO2 Max and Aerobic Power.

    The speed is increased by 1 kmh-1 every minute (so after one minute of running at 8.5 kmh-1, the person must run the second minute at 9.5 kmh-1). The same pattern is repeated only this time, because the person (the subject) is running at a higher speed during the same amount of time (one minute), they are going to cover a larger distance and therefore more of the 20 meter laps (in theory anyway). This fact only works in theory because will most of the speeds, the subject can not run a set (integer)

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  5. A Comparative Study of the Density of Patella Vulgata (Common Limpets) in the Optimum Niche on an Exposed and Sheltered Rocky Shore.

    Black lichen (Verrucaria mucosa) also grows on the back of the limpet's shell. Figure 4. Boulder showing limpet radula marks. Clamping down at low tide prevents desiccation (drying out). Limpets clamp down onto rocks to reduce their metabolism, which helps reduce the need for water when the tide goes out. They can adhere to the rock with a force of 75 lbs/sq.in. making them very difficult to move. After four years of growth, limpets can be 5cm across at the base.

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  6. Energy absorbed by a bouncing ball.

    The ball therefore rebounds with less kinetic energy and so will rise to a lower height than its starting position. The initial potential energy equals mgh (mass x gravity x height). Therefore, if no energy is lost as the ball falls through the air, the kinetic energy, 1/2 mv�1 (1/2 mass x velocity�), will be equal to the loss of potential energy (mgh1). The potential energy at a maximum height after the first bounce equals (mgh2). Therefore, the initial kinetic energy after the bounce equals (1/2mv�2), which equals the potential energy, equal to mgh2.

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  7. To investigate how much energy (Kj) is stored in different types of peanuts and how much is released.

    According to research, peanuts are known to be a good source of protein and fat. When human beings respire they use fats to provide energy, and this respiration releases heat energy from food and in this case: peanuts. As fatty acids (or peanut oil in the peanuts) release energy when oxidized, the fat must react with the oxygen. As the oxygen surrounds the peanut, a small electric current passes through it and after the heat, it becomes hot and as it does so, it catches fire by the direct combination with oxygen. When this is done, energy is released as heat energy and can heat up a container.

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  8. Title: Temperature Equilibrium in Squash Balls.

    The sites I found most useful were: http://www.worldsquash.org (website of the sports governing body) http://www.dunlopsports.com/europe/ (manufacturers of 90% of balls) http://www.squashplayer.co.uk/magazine/balls.htm http://www.phys.virginia.edu/Education/outreach/8thgradesol/EffectofTemperatureFrm.htm (University of Virginia) I also read an article called "Bounce, Balls, and Surface Temperature: A look at seven different squash balls and how surface temperature affects their bounce" by Steve Edgar, an American researcher and squash fanatic, in January 2000. I obtained a copy of the Rules of Squash publisher by the World Squash Federation ("WSF") as I had discovered there were strict guidelines on the manufacture of both squash balls and the courts.

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  9. The theory of relativity and its use in Sci-Fi.

    Science fiction has for years tried to incorporate the theories that govern the reality of physics within their programmes, to keep those die hard science fiction fans happy. Science fiction has been subject to cult following for many years and in many countries, although no matter how hard they try there are a number of important facts that seem almost popular to overlook, the main one being travelling at the speed of light. Many programmes have some sort of light propulsion, warp drive and travel to other universes.

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  10. Current Research in Nuclear Fusion Power and Its Place in Future Electricity Production.

    Hence also energy is released when they are taken apart. When considering the fusion reaction, the total mass of the deuterium and the tritium nuclei before the reaction is more than that of the helium nucleus and neutron formed. This is because the neutron that is emitted is no longer held by the strong nuclear force, the forces have been rearranged at the end of the reaction ending up with a lower potential energy. This energy that once held the neutron is carried away as translational kinetic energy, which does not affect the particles' mass, largely by the neutron.

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  11. Investigation into the Effectiveness of Insulation at Preventing the Loss of Thermal Energy from the Home.

    This happens when the molecules with a lot of energy pass their energy on to the molecules next to them. Because when molecules have energy they vibrate, this is how the energy is transferred, through vibrations. For heat to radiate it does not need to be in contact with matter, as thermal energy can be radiated through a complete vacuum. A good example of this is how the thermal energy from the sun is radiated to earth through space.

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

    This mechanism was first proposed by Mitchell in 1961, and was called the chemiosmotic hypothesis. The electrochemical gradient that drives ATP synthesis can be produced by the photolysis of water (in chloroplasts only) or by the energetically favourable oxidation of the highly reduced compound NADH (and FADH2). This can be expressed by the following equation: 2NADH + O2 + 2H+ ( 2NAD+ + 2H2O ?Eo=1.14V Which can be broken down into the following half-equations: NADH ( NAD+ + H+ + 2e- O2 + 4H+ + 4e- ( 2H2O The potential difference between NADH and oxygen is very high (1.14V)

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  13. Feeding The Third World

    The greatest strength of monoculture is uniformity; Greater densities of planting can be accomplished, commonly delivering higher yields. Much of the "Green Revolution" that started in the 1950's and helped increase the agricultural production in India during the 1960's and 70's was based on monocultural methods. Genetically engineered (and selectively bred) organisms, with desired features, can be reared in large numbers. Genetic Engineering, or Recombinant DNA Technology, allows the isolation of a portion of DNA from an organism that can be inserted into the DNA of another organism, so as the first organism can continually produce the substance the extracted genetic sequence codes for.

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  14. Discuss the Advantages and Disadvantages of being Ectothermic and Endothermic for Vertebrates.

    Consequently, the new terms of ectothermy and endothermy are used. An ectotherm has a high rate of thermal conductance and a low rate of heat production; the body temperature is therefore determined by the environment. However, endotherms are capable of raising the temperature of their tissues above that of the environment, due to the heat from metabolism. Heat can be transferred by a number of means (Adams & Iampietro, 1968): * "Conduction...thermal energy exchange through a medium or between objects in a physical contact by the transfer of intramolecular energy, not involving the transfer of material."

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  15. Explain the basis of ATP generation in mitochondria and chloroplasts. How does this differ from the Substrate level Phosphorylation found in glycolysis?

    During ATP synthesis the reverse reactions occur. Why does ATP have such a high phosphoryl potential (phosphoryl group-transfer potential)? The answer to this question lies in the comparison of the structures of both ATP and its hydrolysis products, because the free energy produced in the reaction depends on the difference in the free energies of the products and reactants (Stryer (1995)). Two factors are important: electrostatic repulsion and resonance stabilisation. The triphosphate unit of ATP carries about four negative charges compared with ADP's three.

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  16. Discuss the Advantages and Disadvantages of being Ectothermic and Endothermic in the Vertebrates.

    All living creatures metabolise and none are a hundred percent efficient. A large fraction of metabolic energy therefore appears as heat, which is released as a by-product. Many animals have such high rates of thermal conductance and low rates of heat production that the heat is lost to the environment. Consequently the body temperatures of these animals are independent of the heat produced by their metabolism and are determined exclusively by the external environment (because of their high rates of thermal conductivity). Such animals are described as ectothermic. In a few groups, however, the metabolic heat production coupled with low thermal conductivity is sufficient to raise the temperature of the tissues above that of the environment.

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  17. Isolation and identification of individual microbes and growth and monitoring of microbes.

    Heat the inoculation loop in a Bunsen flame until it glows red and is sterilised. This will kill any micro-organisms that are present on the inoculation loop 10. Sterilise the rim of the receptacle that the micro-organism is stored in, by moving it through a Bunsen flame. To kill any alien micro-organisms that might be present. Streaking plates: Starting at a '12 o'clock' point dip a sterile inoculating hoop into the sample, then making quick stokes, spread the sample on the media as in the above picture. Be careful not to keep the petri lid of for to long, or to let your fingers touch the media, as this will introduce alien micro-organisms to the media.

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  18. What is Bernoulli’s Principle? Give examples of its diverse ‘use’ or ‘exploitation’ in animals.

    Living organisms employ either one, or the other, or both. The first is adequately illustrated by the phenomenon known as lift. A simple demonstration of lift is to hold the edge of a piece of paper to your lips and blow across its upper surface - the paper should rise as a result of the reduced air pressure above it caused by the faster moving air. The second is the induced flow of fluids. Another mechanical process known as viscous entrainment is also effective here and can contribute to the effect produced by Bernoulli's Principle.

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  19. Investigate the effect of changing the sugar concentration on the rate of respiration of yeast.

    The molecules start to move around slowly but as the heat level rises the molecules race around quickly. When these molecules race around it is known as the collision theory. As the heat energy increases the molecules have more kinetic energy. The particles can only react if they collide into each other. So the molecules are more likely to react when they are going faster. So by keeping the water temperature at a constant of 40(, the experiment should be fair and there will be no disadvantages or advantaged results because they will be equal. Also the enzymes are not destroyed by too high a temperature and do not become denatured.

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  20. Flat periwinkle Investigation

    if different colours of flat periwinkle carry unique genes that effect the species vulnerability to disease or behavioural patterns for example, then differences in shell colour will have a significant effect on the distribution of the flat periwinkle. The flat periwinkles interactions with the abiotic environment could change as a result of shell colour. As different colours absorb heat at different rates, with darker colours absorbing more heat then lighter colours, there could be a relationship between the internal temperature of a flat periwinkle and its shell colour.

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  21. The World Demand for Power

    Despite this lack of commitment the fact is oil, coal and gas take centuries to produce whilst we are using them at a ridiculous rate. The end of the 'tank', which governments seem to fail to accept exists, must therefore be quickly approaching. Recent prediction indicate we have approximately 40 years, continuing at the current rate of power use, until the oil we have discovered dries up. Gas also has an estimated 40 years whilst coal resources are much greater and are expected to last for another century.

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  22. Investigation into how Lichen growth is affected as you move further away from a river

    There are 25000 species of lichen.3 Lichens must compete with plants for access to sunlight, but because of their small size and slow growth, they thrive in places where higher plants have difficulty growing. Lichens are often the first to settle in places lacking soil, constituting the sole vegetation in some extreme environments such as those found at high mountain elevations and at high latitudes. 7, 8, 9 .Some survive in the tough conditions of deserts, and others on frozen soil of the Arctic regions.

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  23. Effects of temperature on the development of a bean plant.

    When water enters the testa the seed expand and the seed coat swells and splits. One other action of the penetration of water is the activation of a hormone called Gibberellic acid. Gibberellic acid counteracts the effects of abscisic acid rescuing the seed from dormancy. Once the effects of abscisic acid have been reversed the digestive enzyme alpha- amylase is activated. This causes the breakdown of starch stored in the endosperm, into sugar that can be used for respiration to produce ATP.

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