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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. The biological significance of carbohydrates in living organisms

    Carbohydrates are used in plants as an energy source, as a means of storing energy (as Starch, a polysaccharide). Cellulose, a polysaccharide, is an important structural component of plant cell walls, where it's tensile strength is important. The products of photosynthesis are transported internally as sucrose (a disaccharide), and the energy source for metabolism in the cells is glucose (a monosaccharide). Animals consume carbohydrates as an important component of a balanced diet, either directly or from eating plants. Humans not only eat carbohydrates (making up 70% of the average diet) but also use them in clothing (Cotton, linen, rayon), housing (wood), fuel (wood), and in paper, books and packaging (wood).

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  2. Investigating the Respiration of Yeast

    Energy is required for respiration (in this case, the transforming of Glucose (C6H12O6) into Carbon Dioxide (CO2)), so there must be a certain amount of energy to start the reaction. Known as 'Activation Energy'. This energy comes from heat energy in atoms, according to particle theory, as the temperature increases, the atoms will vibrate faster. However, adding certain enzymes to the reaction allows the activation energy to be lower. These enzymes require heat energy however to do this. In the human body, enzymes will denatureate over a temperature of 460 C, so, therefore, I will not allow the specimens to reach temperatures of above 500 C.

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  3. Aim: To see how productivity of algae and Elodea changes with depth in a simulated lake.

    Fill each bottle with pond water and add a strand of Elodea. Secure the correct number of OHP films around each labeled bottle. Use the elastic bands to hold them in position. Take care not to cover the Elodea. Cover the dark bottles in aluminum foil. Measure the DO in mg/l in each bottle and record in a table ? these are the initial readings. Record each bottle three times after stirring the probe gently for 10 seconds. Place each bottle on its side under the light array.

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  4. Abiotic Factors Affecting Organisms - revision notes

    Humidity Hygrometers may be designed for indoor or outdoor use (or both). Analog hygrometers use a moisture-sensitive material that is attached to a coil spring. The spring controls a needle on an easy-to-read circular dial. Analog hygrometers are often part of a durable, weather-resistant device that also includes a thermometer. Digital hygrometers determine the relative humidity by using a sensor to monitor an electric current that is affected by moisture levels. Relative humidity, expressed as a percent Salinity Salinity is often measured by measuring how well electricity travels through the water. This property of water is called conductivity.

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  5. Explain how the digestive, cardiovascular and respiratory systems are interrelated

    This is so that it can then go through the capillary wall and enters into the cardiovascular system. The oxygen that travels and diffuses through the respiratory system then reaches the cardiovascular system. These two systems work very closely together to ensure that every tissue within the human body receives oxygen, and that carbon dioxide is removed from the body. The oxygen that is breathed in is transferred to the blood; this blood is then circulated by the heart. This then oxygenates blood throughout the body from the lungs.

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  6. Discuss how physical and mental stress can have good/ bad effects on the body

    Evidently, it is clear that stress poses some degree of strain on an individual; however, the distinction between the benefits of physical stress and adversity of mental stress have yet to be discussed. The fight or flight syndrome (Walter Cannon 1932) explains that the stress response is activated through sympathetic stimulation of the central medulla region of the adrenal glands.

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  7. Aim : To investigate the effect of light on the rate of photosynthesis

    of the capillary tube and meniscus of the fluid within the tube. The movement of the fluid was recorded with time in a well illuminated area. The procedure was repeated for a dark area. All the while the test tube containing the elodea was immersed in a beaker of water to ensure constant temperature conditions.

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  8. The Effect of Caffeine on Daphnia Heart Rate

    Caffeine at high levels of consumption have been linked to insomnia, anxiety, restlessness, blood pressure and raised stress. This can all lead to heart and circulatory problems. The effects of caffeine on the heart rate of Daphnia can be investigated by putting Daphnia in a caffeine concentrated solution and then taking them out to put under a microscope. The unique structure of Daphnia allows us to measure its heart rate by the amount of times their legs move. The experiment is to find out the effect that caffeine has on the heart rate of Daphnia. My hypothesis is that the higher the percentage caffeine solution the faster the Daphnia heart rate.

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  9. Translocation is the method to alleviate the overbreeding problem of animal besides killing them.

    But Tufts University has done the measure on translocation and found out the solutions (Biological Conservation Molly J. Dickens 2010). Administering anesthesia or tranquilizing during capture, reduce the risk of the animal perceive handling and transport. Normally, Health assays, veterinary visits, or other forms of observation and intervention are conducted during captivity, decrease the total number of visits, thus decreasing added exposure to handling stress. Specific aspects of transport such as vehicle design, stacking density, ventilation, and even the quality of the road and the standard of driving should be measured before translocation. Finally, the use of a ??soft-release? strategy, in which animals adjust to the area in a special designed cage before being released, may decrease novelty

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  10. Daphnia Heart rate-caffeine

    After this count the daphnia?s heart rate for 5 seconds and multiply the result by 12 to get the heart rate for a minute. Get another person to count the time using a stopwatch and record the results in a table. Repeat this adding a drop of caffeine (0, 1, 2, 3 drops) each time, but wait for a minute before counting the heart rate to make sure the caffeine has taken effect. Repeat this with 5 different daphnia to make the results of the experiment more reliable.

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  11. Effect of caffeine on heart rate on Daphina

    This experiment is useful because it proves that caffeine is a stimulant that affects the heart and body, excess drinking of caffeine can be very harmful to the body as it could increase chances of cardiovascular disease. Equipment and justification: Culture of daphnia To examine the effects of caffeine on it?s heart rate Cavity slides Holds any liquids in place Pipettes To drop amounts of liquids Distilled water Used in the control, to compare it with caffeine Caffeine table Make different concentrations of caffeine Cotton wool Restricts movement of daphnia Standard glassware Hold liquids in.

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  12. Biological Cycles

    First nitrifying bacteria change ammonium into nitrites, then other nitrifying bacteria called Nitrobacter turn nitriles into nitrates. Denitrification is when nitrates in the soil are converted into nitrogen gas by denitrifying bacteria, During this process the bacteria use nitrates in the soil to carry out respiration and produce nitrogen gas which then goes back into the air. This only happens under anaerobic conditions e.g in waterlogged soils. Another crucial biological cycle is the carbon cycle. All organisms need carbon to make essential compounds, therefore it is important that it is continuously used and returned back to the atmosphere.

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  13. How does caffeine affect the heart rate of Daphnia?

    Pipettes 2. Test tubes 3. Stop clock 4. Microscope 1. Daphnia 2. Cavity slides 3. Distilled water 4. Caffeine solutions 5. Cotton wool Plan: 1. Use a range of caffeine solutions of different concentrations and a control solution that has no caffeine in it at all (so I have a set of results that I can compare to) 2. Place a few strands of cotton onto the cavity slide; this will help restrict the movement of the Daphnia making it easier to see under the microscope. Using a pipette transfer one Daphnia into the dimple of the cavity slide.

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  14. Testing the effect of water temperature on the respiration rate of goldfish

    Experimental Design: 1. Experimental/ Independent Variable – Temperature of water 2. Dependent Variable – Amount of breaths taken by the fish 3. Control – First trial, Breaths taken: 89 Initial temperature: 25 ® C Constants: 1. The fish 2. 1000 mL Beaker 3. Aquarium water 4. Amount of time taken to record number of breaths 5. Thermometer Materials: 1. Thermometer 2. Goldfish 3. 1000 mL Beaker 4. Distilled water 5. Ice 6. Hot plate 7. Timer Procedure: 1. Fill 1000 mL Beaker half way with distilled water, and then record the initial temperature of water.

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  15. Limpet Size Investigation

    The splash zone (more than 7.8m above chart datum) is always emersed. Information on Limpets Kingdom: Animalia Phylum: Mollusca Class: Gastropoda Order: Patellogastropoda Description: Limpets have flattened, cone-shaped or cap-shaped shells with concentric growth lines and radial ribs that extend from the edge of the shell to the apex. Their size ranges from about 5 to 200 millimetres in length. They usually adhere strongly to rocks using pedal mucus and a muscular "foot", enabling them to attach securely to the rocks, in spite of the intensity of the wave action.

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  16. Adenosine Triphosphate.

    Together, these biosynthetic reactions are called anabolism. Conversely, most energy yielding reactions in cells breakdown molecules to obtain building blocks, release energy or digest waste products. Together, these degradative reactions are called catabolism. In order for a living organism to do work endergonic reactions must be linked with exergonic reactions. The energy that the body requires is provided by respiration where the aerobic oxidation of a glucose molecule provides 2870 kJ of energy. Respiration is not just one big reaction but is in-fact a series of small steps with each reactions being regulated by enzymes.

    • Word count: 735

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