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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.

• Marked by Teachers essays 42
• Peer Reviewed essays 15
1. ## Fighter Pilot A Statistical Analysis of Reaction time and its Correlation with Dominant & Non-Dominant Hands

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The transmission is then sent to the precentral gyrus, the primary motor complex and a transmission of a motor impulse is carried down to the spinal cord to motor neurons and finally to the muscles of the hand effecting the movement through the contraction of muscles. (2) This journey of information from receptor to effector in the human body is very complex due to the various neurons and synapses involved. Due to this complexity the human brain and nervous systems ability to process information and relay a response may be hindered or facilitated by many different internal or external factors.

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2. ## An investigation into the effect of different sugars on respiration in yeast.

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Even if there is a limited supply of oxygen, yeast can still release energy from sugar. However, the by-products of this are alcohol and carbon dioxide.i Yeast respires in anaerobic conditions. This means that the pyruvate will be converted into carbon dioxide and ethanol. To do this, the enzyme pyruvate decarboxylase removes a carbon dioxide molecule from the pyruvate. The acetaldehyde that is formed is then reduced by the enzyme alcohol dehydrogenase which transfers the hydrogen from NADH to the acetaldehyde to yield NAD and ethanol.ii C6H12O6 + 2 ADP + 4 H+ + 2 HPO42- � 2 C2H5OH + 2 CO2 + 2 ATP + 2 H2O Yeasts are active in a very broad temperature range - from 0 to 50?

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3. ## Effect of nitrate concentration on the growth of Duckweeds

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As I repeated the process for all the other 5 concentrations of nitrate in solutions, each time when I used different concentrations of nitrates I made sure that I washed out and dried the beaker and the syringe, to avoid any contamination of the solutions as this would lead to the concentration of nitrogen and other nutrients to change, therefore affect the outcome of the results. Each time I used a syringe that had accuracy of + - 0.1cm3 , as it would give me a accurate reading of the solution I put inside the wells.

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4. ## Effect of Anaerobic Respiration On Yeast

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They will grow from 10�-37�C, with optimum temperature in the range of 30�-37�C, depending on the species. There is little activity in the range of 0�C-10�C. Above 37�C yeast cells become stressed and will not divide properly. Anaerobic respiration occurs when no free oxygen is present to remove the hydrogen. This therefore means the electron transport chain cannot continue to function and no more ATP can be produced via oxidative phosphorylation. Hence why a form of respiration is required without the need for oxygen. Anaerobic respiration or fermentation as it is called when referring to some plant species (including yeast).

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5. ## effect of temperature on the rate of respiration in yeast

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A ten degree Centigrade rise in temperature will increase the activity of most enzymes by 50 to 100%. Variations in reaction temperature as small as 1 or 2 degrees may introduce changes of 10 to 20% in the results. The rate of reaction increases as the temperature increases. The rate of reaction increases till it reaches it its optimum level; this is when the rate of enzyme activity start to decrease and enzymes started to denatured. (Reference 2) Collision theory: As the temperature increases particles start to move quickly and collide with each other with greater energy. It also increases the number of particle.

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6. ## Investigation on the size of Limpets.

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The mechanism by which this occurs is still unknown. An increased amount of algae results in more energy being available in the food chain as algae are photosynthetic organisms that convert sunlight energy into chemical energy. Algae, as well as other plants, store this energy as carbohydrate through the process of photosynthesis. Photosynthesis occurs in two stages - the light dependant stage followed by the light independent stage. In the first stage, reduced NADP (nicotinamide adenine dinucleotide phosphate) and ATP (adenosine triphosphate) are synthesised by conversion of photon energy to electrical energy in the light harvesting clusters found on the thylakoids of chloroplasts.

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7. ## Home Economics - Why is nutrition important to sports people?

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The nutrition of an athlete is very important to their success at the sport. All sports place specific demands on the athlete and these are usually controlled through the diet. The key to success in any sport is performance which is obtained through reaching all the necessary energy and protein requirements as well as the vital vitamins and minerals. The IOC consensus statement on sports nutrition says "The amount, composition and timing of food intake can profoundly affect sports performance. Good nutritional practice will help athletes train hard, recover quickly and adapt more effectively with less risk of illness and injury.

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8. ## The Effectiveness of Different Solutions to Prevent or Treat Malaria

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Fever 2. Shivering 3. arthralgia (joint pain) 4. vomiting 5. anemia (caused by hemolysis) 6. Jaundice 7. hemoglobinuria 8. retinal damage convulsions. Methods: Now, in the 21st century no 100% treatment against malaria is available. But the most common ways to treat malaria is through Antimalarial drugs which are used in order to prevent or cure malaria. Such drugs may be used for some or all of the following: 1. Treatment of malaria in individuals with suspected or confirmed infection 2. Prevention of infection in individuals visiting a malaria-endemic region who have no immunity (malaria prophylaxis) 3. Routine intermittent treatment of certain groups in endemic regions (intermittent preventive therapy)

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9. ## The Ways in Which Organisms Use ATP

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Furthermore, ATP is utilised elsewhere within the same process, as it is used by carrier proteins on the membrane of the sarcoplasmic reticulum as a source of energy for the active transport of Ca2+ ions into the sarcoplasmic reticulum. It is when these calcium ions are secreted that the troponin C subunit allows the tropomyosin to reveal the myosin binding site on the actin filament ready for muscle contraction. Whilst ATP is one of the main products of respiration, it is interesting to note that within its first stage, glycolysis, 2 ATP molecules are actually used initially in order to phosphorylate the glucose molecule, forming phosphorylated glucose.

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10. ## Studying the Effect of Salt on Cress Germination

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Count and record the percentage I chose to carry out my method in this fashion as it gave me the best way to see which salt concentration had the biggest effect. I chose 8 solutions as it gives me a good range to monitor the salinity effects. The solutions are based on findings in earlier research and I chose to go up to 1.75 grams to see whether this would affect cress regardless of it being a particularly high concentration.

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11. ## In this study I will investigate the length and width of Fucus Serratus fronds found at two different zones on a rocky shore in Abbotsham, Devon, UK. I will look at an upper shore line zone and in comparison to a lower shore line to collect data from

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Independent variables are the things that I will be changing throughout the experiment: - The location of the quadrat in each different zone. I will use a random sampling method of systematic sampling to vary my data. Random numbers will act as the vectors for the quadrat location. Confounding variables are those things which will have an affect on the dependent variables. These variables are also referred to as controlled variables as they can be controlled in situations and minimised to certain extent to ensure that conditions remain the same throughout the research.

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12. ## Experiment examining the effect of mineral deficiencies on plant growth.

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A plant lacking magnesium would be unable to produce chlorophyll therefore the leaves would become yellow coloured and not so green. The plant lacking calcium would have a stunted growth due to the role of calcium ions in the structure of the cell walls and membrane permeability. I expect the plant lacking all nutrients to have all three of these properties and possibly just die out completely. The plant containing all the nutrients should grow normally without many problems related to the nutrients.

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

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This is made further efficient by the chloroplasts which take up a position where they will absorb maximum light without shading other chloroplasts below them. In sun leaves however, the chloroplasts expose themselves to light at different times with those already having been exposed to light taking shelter in the shade of others so as to prevent overexposure, which would destroy the chloroplasts. High light intensity means that sun leaves do not have a need to grow as rapidly as shade leaves hence their shorter internodes and smaller leaves.

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14. ## How does the Variety of plant species change between grassland and woodland?

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The species best adapted are more likely to survive by out-competing others for vital resources. Interspecific competition is competition between different species for a particular resource in short supply and occurs when the niches of two species overlap�. (The niche of an organism is its role in the ecosystem�). There is a very great difference between the various types of grasslands. Not all grasslands are intensively farmed. Some grassland will be on poor marginal lands which are typically of low fertility. Non-intensive grasslands produce less of value in the way of a grass crop. There are many different types.

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15. ## Abundance of vegitation

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It can withstand trampling and compaction and is common in gateways and on paths. It can tolerate both water logging and a moderate drought. 1 Scientific classification Kingdom: Plantae Division: Magnoliophyta Class: Magnoliopsida Order: Ranunculales Family: Ranunculaceae Genus: Ranunculus Species: R. repens White Clover Trifolium repens L. White clover is a procumbent perennial, native in grassy and rough ground. It is common throughout Britain and is most frequently found in soils of pH 5.0 to 8.0. It is common on clay soils but is rarely found on peat. White clover is sensitive to shade, drought and severe frosts.

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16. ## Affects of Inter and Intra Specific Competition between Wheat and Mustard plants

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Findings suggest that competition indeed, does exist, and was clearly shown in our results in (lower seed production (yield) and differentiation in length of individual plants). Hypothesis: If plants of different or the same species are planted within vicinity of one another that there is a possibility of competition between them then competition will occur and one of the competitors will eventually be eliminated from that specific location. Methods: 1) Label one envelope for each of the treatments with the pot number, number of mustard seeds and/or wheat plants.

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17. ## How caffeine affects Daphnia heartbeat?

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The independent variable I will change is the concentration of caffeine in the water. I am going to be testing 0.1%, and 0.5% caffeine and also a distilled water trial. This means I will be able to see if the heart rate is greater with caffeine or not. The variable we are going to measure is the rate of the Daphnia's heartbeat and to do this we will use a microscope to count the heartbeats of the Daphnia for 15 seconds.

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18. ## 'An investigation into the ability of two strains of the yeast Saccharomyces cerevisiae to utilise different carbon sources as substrates for cellular respiration'.

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Due to the substrate being complimentary in shape to that of the enzyme's active site, they fit together as a key would in a lock. The binding together of the enzyme and substrate results in the substrate being hydrolysed. In the case of yeast respiration, this degradation turns the substrate into a form more usable in glycolysis, the first stage of cellular respiration. Enzyme + substrate ?enzyme-substrate complex ?enzyme + product Respiration of yeast will be most rapid when glucose is available as a substrate, because it is the simplest usable carbon source, and will be used preferentially in its role as a precursor of glycolysis.

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19. ## The Development of Antiseptics.

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Semmelweiss' ideas on cleanliness Ignaz Semmelweiss had noticed that there was an unusually high death rate amongst women after childbirth and realised that mothers whose children were delivered by a mid-wife usually survived unlike those who had there offspring delivered by medical students. Semmelweiss thought that if only the students washed their hands before entering the maternity wards they may save many lives, he made them do this and it worked. Unfortunately Semmelweiss was ignored, he called those who did not wash their hands 'murderers' and so many called him a crank and a fanatic.

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20. ## A comparative study of the density of patella vulgata (common limpet) across a sheltered shore and an exposed shore.

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The common limpet creates a home scar on the rock to which it attaches itself to, this allows it to clamp tightly to the rock, which reduces water loss during periods of emersion. The species is tolerant to long periods of exposure to air and can survive up to 65% water loss. Limpets that live lower down the shore have lower tolerance to desiccation, also smaller limpets are more exposed to desiccation than larger ones. Limpets are mobile species so patella vulgata has the ability to determine its position on the shore relative to its preferred zone, it can adjust the direction it wants to go and can move into more suitable conditions.

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21. ## To make sure we have plenty of energy in the future, it's up to all of us to use energy wisely. We must all conserve energy and use it efficiently. It also ups to those of you who will want to create the new energy technologies of the future.

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Oil or Petroleum To find oil and natural gas, companies drill through the earth to the deposits deep below the surface. The oil and natural gas are then pumped from below the ground by oilrigs (like in the picture above). They then usually travel through pipelines, like the ones in the picture to the right in Alaska. Oil is found in 18 of the 58 counties in California. Kern County, the County where Bakersfield is found, is one of the largest oil production places in the country.

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22. ## How is ATP produced and used in living organisms?

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forming ATP. The excess hydrogen ions are removed by the aid of NAD to form one molecule of reduced NAD per pyruvate. If the organism is anaerobic or when the supply of oxygen is not enough for the energy consumption taking place, the NAD supply must be replenished, which involves oxidising the NAD and transferring the hydrogen to another molecule. This can be done in two ways, through producing Lactic acid or producing Ethanol. Neither of these produces anymore ATP, meaning the product (as four are made but two ATP molecules must be used to start the process)

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23. ## Tuberculosis and its treatment

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WHO estimates that eight million people get TB every year, of which 95% live in developing countries. An estimated 3 million people die from TB every year. In industrialized countries, the steady drop in TB incidence began to level off in the mid-1980s. Much of this rise can be at least partially attributed to a high rate of immigration from countries with a high incidence of TB. It is also difficult to perform epidemiological surveillance and treatment in immigrant communities due to various cultural differences.

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24. ## Find the relationship between amount of fat and amount of energy produced in different foods.

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This would cause a false rise in temperature. The distance of the boiling tube from the Bunsen burner must be kept constant. The Bunsen burner provides heat and different distances from it would be at different temperatures. This could cause the temperature of the water to rise falsely, and would again produce anomalies. The distance of food from the boiling tube must also be kept constant. There is a different temperature at different points of a flame. The tip of a flame is the hottest part.

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

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Hypothesis: I think that the Daphnia's heart rate will rapidly increase when the caffeine solution is added. This is because increases the amount of neurotransmitters released in the body so everything in the body will be working at a faster rate because of these. Planning: -Risk Assessment: 1. I need to be aware of weils disease so I will not come in to direct contact with the pond water and regularly wash my hands thoroughly throughout the experiment. 2. I will need to constantly keep my glassware on throughout the experiment to prevent any substances getting into my eyes 3.

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