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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.

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 Role of Lipids In Living Organisms

They are more compact because lipids, "tend to be only minimally hydrated and, in turn, clumps of lipids (hydrophobically excluded) take up even less volume (and mass) than storage carbohydrates"(4) The role of tryglycerols goes beyond energy storage. Tryglycerols, commonly known as fat in animals and oils in plants is used to aid buoyancy of aquatic vertebrates such as sharks, seals and whales. This is done because lipids are less dense than water. "Sharks have extremely fatty livers which make up to 25% of their body volume and contain a lipid, squaline, with a specific gravity of only 0.86."(2)

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2. Effect of Temperature on the rate of respiration

Test samples of Saccharomyces Cerevisiae, brewer's yeast, shall be mixed with a small amount of glucose and will be maintained at temperatures of 0�C, 22�C, 40�C, 60�C and 90�C. Each test tube will then be monitored closely and the number of carbon dioxide gas bubbles given off over a ten-minuet period of time will be recorded in a table. The temperature of the test solution that evolves the highest number of bubbles will be considered the optimum temperature for respiration to occur in yeast.

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3. To collect and identify species of organisms and plants in an area of 1m2 in a pond.

and to then put them into pyramids of numbers and biomass. Method: ?????????????????????????????????????????????????????????????????????? ????????????????????????????????????????????????????????????????????????????????? ?????????????????????????????????????????????????????????????????????????????? ??????????????????????????????????) for obtaining organisms you have to fill the trays with roughly half pond water, preferably away from the area you are studying to make it a far test so you are not taking out any organisms out of your area. Then you use a net to sweep through the top layer of water of your area making sure the whole area have been swept. Do this round 3 times to make sure you have obtained enough organisms.

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4. Investigating the energy released from burning fuels

Then when we've calculated these two we can divide them to get a figure for the overall energy released. Bond Energy Values Bond Bond Energy C-H 435 O =O 497 C= O 803 H - O 464 C - C 347 C - O 358 These are how the bonds are formed in each fuel: Methanol Ethanol Propanol Butanol Total Energy Needed (To break the Bonds): CH3OH (Methanol) + 1.5O2 (Oxygen) = Total Energy Needed 3 x 435 + 358 + 464 = 2127 (The Total Bond Energy needed for Methanol)

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5. Frost&#146;s &#147;The Wood-pile&#148;

This energy is used to combine water, carbon dioxide and minerals into sugar and other organic compounds. In order to bond these raw materials, energy is needed, making this reaction endergonic. Birds then eat plants or other animals that eat plants and acquire that energy found in the sugars and organic compounds. Plants and foods are broken down into glucose. This process is exergonic and releases energy that is built up in the bonds of plants and other foods.

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6. Habitat Study Of Belfast Lough Foreshore

This would be marked out by rope. We would position a quadrant (0.5m2) at each of these points and count the number of organisms in each area or estimate the percentage coverage of the area if the organism was seaweed. The temperature and light intensity was to be recorded on a "LogIT Datameter 1000" We made sure it was a fair test by everyone using the same size of quadrant, measuring at equal distances along the rope and everyone measuring with the quadrant touching the rope. We also chose an area that was partly dry, partly damp and partly wet.

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7. Ocean Wave Energy

The devices are classified into large-scale offshore devices and small-scale shoreline devices. Most of the development is on large-scale offshore devices, such as the oscillating water column (OWC). China has constructed a 3 kW OWC shoreline device, which has an artificial gully and a Wells turbine.

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8. 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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9. Report on visit to Medway Hospital.

In Urology it is used to detect prostrate cancer early, to find kidney stones and to measure blood flow through the kidney. An ultrasound wave is a high energy longitudinal wave, it operates at a frequency higher than the human ear can detect. Ultrasound is used in medicine in the following way. A special gel is applied to the part of the body which is to be scanned this acts as a coupling agent so that the waves pass right into the body without having to pass through air first.

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10. 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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11. Whether temperature effects respiration

In this type of respiration, food molecules are gradually processed into carbon dioxide and water, and large quantities of energy are produced. Some of this energy produces heat, but most of it is stored in molecules of adenosine triphosphate (ATP). When the stored energy is needed, ATP is quickly processed and the energy is made available for use by the body. The first step in aerobic respiration occurs in the cytoplasm of the cell and involves breaking down glucose. Each glucose molecule is made up of six carbon atoms plus hydrogen and oxygen.

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12. Chemistry Coursework : Neutralisation

Energy level diagram: Energy transfer: A reaction that gives out energy is called n exothermic reaction. A reaction that takes in energy is alled an endothermic reaction. Exothermic reactions can feel hot as energy is taken in. Endothermic reactions can feel cold as energy is taken in. The energy change in a reaction is often given the symbol /\H.

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13. The iodine clock mechanism

As there is a low temperature there is not enough energy to make the particles collide. Temperature high There is more chance of collision. By kirsty skidmore By kirsty skidmore As there is a high temperature there is a higher amount of energy so there are more collisions. Since in the first experiment is to see how concentration makes a difference on the speed of the iodine clock reaction the dependent variable is time. For the measurement of time in my experiment I decided it would be best to use a stopwatch. In this experiment I am going to record the time taken for the solution to go blue black while being shaken I am going to do each experiment three times.

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14. To calculate the energy per mole of substance

METHANOL (CH3OH) 1 2 3 mean average total mass of burner before burning (g) 144.90 144.40 145.00 144.77 total mass of burner after burning (g) 143.40 142.90 143.50 143.27 mass of alcohol burned (g) 1.50 1.50 1.50 1.50 mass of water (kg) 0.1423 0.1420 0.1426 0.1423 starting temperature (deg. Centigrade) 17.00 17.00 17.00 17 final temperature (deg. Centigrade) 28.00 28.00 28.00 28.00 change in temperature (deg. Centigrade) 11.00 11.00 11.00 11.00 RMM 32.00 32.00 32.00 32.00 moles of substance burned =Mass/RMM 0.0469 0.0469 0.0469 0.0469 energy=mc 6.57 6.56 6.59 6.57 energy per mole = energy value from table(1/number of moles burned)

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15. How temperature will affect the respiration of an organism.

When our body temperature increases or we do exercise our muscles use more oxygen and produce more carbon dioxide. This leads to both an increase n tidal volume and frequency of breathing due to demand for oxygen within the respiratory system. The most vital part of the respiratory system in humans starts in the inspiratory center located in the medulla of the brain, which consists of nerve cells. Nerve impulses pass down the phrenic and intercostal nerves causing contractions within the diaphram and external muscles, which then brings about inspiration. Expiration can be assisted by nerve impulses from the expiratory center, which causes contractions of the internal intercostal muscle.

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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. Investigation into the alcohol fermentation of yeast

Alcoholic fermentation is far less efficient at giving energy than aerobic respiration. When one mole (180g) of glucose is respired aerobically, 2880kJ of energy are transferred. The equivalent figure for anaerobic respiration is 210Kj. A lot of energy is kept in the alcohol. This can be shown in the combustion of alcohol when energy is transferred into the surroundings which, as a consequence, become warmed. In conclusion, alcoholic fermentation is much less efficient than aerobic respiration but it can still supply some organisms with enough energy to maintain them when oxygen is low.

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19. Investigating the effect of pollution on freshwater invertebrates, using Mayfly Nymph as an indicator.

Eutrophication Eutrophication means nutrient enrichment. The main factor that causes eutrophication is the heavy use of nitrogen fertilisers and the increase in discharge of phosphates from sewage works. Nitrates and phosphates are the nutrients that are usually limiting primary productivity in aquatic ecosystems. Therefore an increase in these nutrients favours an increase in rapidly growing competitive plankton species. Consumer organisms cannot increase in number as quickly in response to environmental change, this means that not all the increased primary production is eaten by the consumer organisms. Death of the primary organisms is therefore broken down by decomposers.

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20. What is Bernoulli&#146;s Principle? Give examples of its diverse &#145;use&#146; or &#145;exploitation&#146; 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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21. How Abiotic Factors Present In an Ecosystem Affect the Organisms

The figure below shows how the performance of any species is affected by an abiotic factor. Physical factors affecting organisms can be divided into 4 main categories: * Climatic - temperature, light, wind and water availability * Edaphic - factors related with soil * Topographic - altitude, aspect and inclination * Others - wave action etc Temperature Environmental temperatures influence the ability of organisms in an environment to survive and reproduce, especially if the organisms are ectotherms (cold blooded), e.g.

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22. Measuring the rate of respiration against mass, in with Earthworms

Mass of worm /g Time /m Dist. moved by liquid in Manometer (for 5min period) /mm O2 Consumption cm3/h 2.76 5 12 1.81 10 13 1.96 1.44 5 9 1.36 10 5 0.75 Average consumption 1.81+1.96 / 2 = 1.89 cm3/h 0.75+1.36 / 2 = 1.06 cm3/h When combined with the rest of the class's data the following graph can be produced to directly compare the relation between mass and O2 consumption (see graph sheet). Conclusion The graph shows us that there appears to be a positive correlation between the mass of earthworms and the amount of oxygen they require, we can tell this as almost all the data lies in the 1st and 3rd quadrants of the graph.

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23. 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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24. I couldn&#146;t wait to get there

Completely unspoiled, blessed with natural treasures and with its fabulous underwater visibility it completely took my breath away. With the healthy reef and exciting marine life, nature lovers would find indigenous wildlife and so did I? I couldn't resist anymore, I took my last breath and prudently swam into a new world under the sea.

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25. Spectrophotometry

Determine the concentration of a solution of cyt c of an unknown concentration, from the calibration curve Please note that when reference is made to different 'concentrations' of cyt c, it is infact referring to the amount of dilution of the standard stock 0.1 mg/ml cyt c Reagents 0.1 mg/ml cyt c solution Diluted 0.1 mg/ml cyt c solution of four concentrations Deionised water Materials and equipment Cuvettes Spectrophotometer 1. Determination of wavelength of peak absorbance Method The method is detailed as in the schedule.

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