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AS and A Level: Molecules & Cells

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  1. Air Training Corps Information System

    '22' and L98' are certificates, and a yes in these columns shows that the cadet has passed Table 2: Attendance Second Name First Name Month 1 Month 2 Month 3 Month 4 Month 5 Month 6 Total No. to date % To date This shows over a six month period when each cadet has attended, what his total attendance is to date and the percentage of attendances to date Table 3: Subs Second Name First Name Month 1 Month 2 Month 3 Month 4 Month 5 Month 6 Total paid to date % Paid Each cadet is due to pay a �10.00 subscription each month.

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  2. Blood and The Immune System.

    They are responsible for the specific immune response- the B-lymphocytes produce antibodies and the T-lymphocytes have a number of roles, including coordination of the immune response and direct cell destruction. Basophils These have an S shaped nucleus and granules that stain blue. They secrete large amounts of histamine that increases inflammation, and heparin that helps to keep the balance of blood clotting and not clotting. Eosinophils These have a double lobed nucleus and granules that stain red with the acid dye eosin.

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  3. Starch and Amylase

    At intervals of two minuets a drop of liquid was removed from each tube and tested for the presence of starch using Iodine solution. The results were carefully recorded in a chart over a period of 30 minuets. For the exact procedure used please see appendix 3. Results The results from the experiment showed that when the amylase solution was maintained at a temperature of 22�C the starch content inside the test tube had begun to decrease significantly by the four-minuet point and had disappeared completely after twenty-two minuets had passed.

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  4. Locusts will be affected by temperature

    There are tubes (Bronchioles) along the side of the insects abdominal clearly visible with the naked eye, which is the passageway into the centre of the insect. These create a larger surface area that means the Insect can exchange gasses with the environment Easily. Also the Bronchioles are moist to assist diffusion since the Gasses are dissolvable in water easily so the chemicals then just travel through the liquid and the membrane, which is very thin. First of all I need a Locust and A Boiling tube to with hold the locust.

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  5. Factors affecting Osmosis in living tissue.

    However if plant cells are placed in a strong solute (sugar or salt) solution the water molecules will pass from the high concentration of water molecules inside the cell out to the solution where there is a low concentration of water molecules by osmosis. As water passes out, the sap vacuole begins to shrink. The cell is no longer firm we say that it is flaccid. As this happens more and more the cytoplasm begins to peel away from the cell wall.

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  6. Discovering the Lowest Concentration Of Lead Ions Needed to Cause the Loss of Partial Permeability of Red Onion Cell Membranes

    This reduces the rate at which water can travel by osmosis through the cell membrane, and hence the cell is less likely to become plasmolysed through water loss when it has suffered poisoning by lead ions, and in addition the chance of deplasmolysation in distilled water is also reduced. (Knowledge derived from References 1 and 4) Method List of Equipment 7 clean evaporating dishes A supply of 1M lead nitrate A supply of 1M glucose solution A 10 ml syringe A stopclock Microscope Red onion Scalpel Ceramic Tile A beaker Slides and Coverslips Forceps 1.

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  7. An Account of the Function of Proteins in Living Organisms

    More specifically collagen gives in the constituent of tendon and cartilage due to properties of strength with flexibility. Another is elastin which as the name implies has elastic properties used in ligaments. Keratin is a very tough protein used for protection e.g. in nails, claws, hooves, scales, rhino horns, and skin. In bone Ossein gives structural support. The next group, Co-ordinated Motion or Contractile Proteins consists mainly of two fibrous proteins. Actin and Myosin these are needed for muscle contraction. These form two filaments one thick (myosin) and one thin (actin) which have the ability to slide over each other giving contraction.

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  8. The effect of osmosis on weighed potato chips

    Bellow is the animal cell: As you can see from this diagram, the animal and plant cell both have a cell membrane but the animal cell is different to the plant cell in other ways, which are all listed below: PLANT CELLS ANIMAL CELLS Have tough cellulose cell walls Do not have cellulose cell walls Have chloroplasts Do not have chloroplasts Have a large permanent Vacuole containing cell sap Sometimes have small vacuoles but they never contain cell sap Many have a box-like shape Shape varies Have a nucleus to the side of the cell Have a nucleus in the

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  9. Investigate how concentration of the enzyme catalase in celery tissue alters the rate of reaction with hydrogen peroxide.

    and by otherintermolecular forces (Nuffield Advanced Chemistry, p.209). Secondary, tertiary and quaternary-structured protein molecules (haemoglobin is an example) are in increasing order of complexity. A tertiary-structured protein molecule is recognised by the supercoiling of the ?-helix (the secondary protein structure, an example is the DNA double helix). The three dimensional shape of the protein is stabilised by a "series of interactions between -R groups on the polypeptide chain". The '-R groups' are unspecified molecules which vary from protein to protein and are the 'active site' of an enzyme.

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  10. The aim of this investigation is to find out how different pH levels affect enzyme activity.

    at high temperature. At lower temperatures enzymes still work although not best. Enzymes are very useful in our day-to-day lives. They help digest food and are produced in our mouth, pancreas and stomach. They break down larger molecules into smaller ones so they can be absorbed into out blood through the small intestine wall. Amylase breaks down starch molecules into simple sugars. Enzymes work by lowering the activation energy, which is the amount of energy required to make or break a bond.

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  11. Compare and contrast the structure and function of Chloroplasts and mitochondria

    The structure and function of mitochondria Mitochondria were first observed with a light microscope by several cytologists in the period between 1850 and 1880. Their black, thread-like appearance prompted C. Benda to name the structures mitochondrion, from the Greek words 'mitos' (thread), and 'chondros', (granule), in the year 1898, (Sadava, David.E. 1993). Diagram of Mitochondria http://www.cbs.dtu.dk The development of improved methods of fixation and the use of transmission electron microscope in 1953 enabled Palade and Sjostrand to describe the basic structural plan of mitochondria.

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  12. The Effect of Temperature on the Activity of Amylase

    As the temperature increases between 25?C and 45?C the rate of reaction increases until the optimum temperature. After the optimum temperature, between 60?C and 75?C, the rate of reaction decreases. Temperature is partly responsible for how slow or how fast as chemical reaction takes place. Chemical reactions take place when the enzyme and substrate collide. At a low temperature, such as 25?C, the chemical reaction takes place a slow rate. This is because there is not a lot of energy in the solution that causes them to move. When you pick a higher temperature such as 45?C, the chemical reaction takes place a lot faster because the particles are colliding more frequently and so results with a higher rate of reaction.

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  13. An experiment to investigate the effect of chloride ion concentration on the activity of amylase

    As such some activity will occur without the presence of cofactors. However when a cofactor is used the enzymes are converted to the R state before the complex forms. This means the substrate can fit into the active site better, and as such the enzyme-substrate complex is formed more easily. Hence, at a given temperature the rate of the reaction is increased in proportion to the number of R-state enzymes present. This in turn is proportional to the number of cofactors present In this case it is a chloride ion, a small ion which is called an allosteric effector, and acts in an opposite fashion to a non-competitive inhibitor (which can also be referred to as an allosteric effector)

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  14. To what extent has genetic manipulation of the Calvin cycle forced the reappraisal of our understanding of the control of metabolic pathways in plants. What do studies of transgenic plants reveal about the integration of metabolism?

    carbamylation of rubisco). Longer-term "coarse" changes, such as those incurred during development, require the amounts of enzymes to be altered, through modification of the transcription of the gene or by protein turnover. Original thinking behind regulation of flux in a pathway has been that enzymes catalysing steps far from thermodynamic equilibrium (i.e. irreversible) are best suited for regulation as they provide a bottleneck for the pathway that relies on their catalytic abilities. Enzymes that catalyse steps that are at or near thermodynamic equilibrium (i.e.

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  15. Catalase Investigation

    Repeat this for the other 3 materials potato, liver and raw liver. Prediction I predict that the raw liver will give off the most oxygen then the potato followed by the apple then finally the boiled liver with no reaction. I think this because the raw liver will produce a higher amount of the enzyme catalyse. This will make a larger amount of oxygen because there is a bigger reaction. I predict that the higher the concentration the faster the reaction will be and the products will be made.

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  16. The theory of endosymbiosis

    Anaerobic amoeba-like Anerobic bacterium Aerobic bacterium bacterium. engulfs aerobic bacterium. becomes symbiotic inside the anarobic bacterium. When the original anerobic bacterium reproduced, so did the aerobic bacterium inside it, so all offspring were an association of the two bacteria. Over time, the two bacteria developed mutually beneficial existence and eventually both partners lost their ability to function without each other. A relationship like this, in which both partners benefit, is called symbiosis. According to the endosymbiotic theory, this is how mitochondria evolved. It is thought that chloroplasts evolved in a similar way, When a primitive cell engulfed a photosynthetic bacterium.

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  17. Factors that affects the rate of breakdown of a substrate by an enzyme

    I have chosen this over the other factors because firstly, temperature will be very difficult to control with the basic equipment used in schools. Therefore, without spending a large amount of money, in specially controlled environments, the results that I would obtain would be inconclusive or incorrect. I could use water baths set at different temperatures to conduct the experiment, but again, this would be inaccurate and ineffective. b) Secondly, pressure. For the same reasons, I am not investigating how pressure will affect the rate of catalysis.

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  18. Investigating How the Concentration of the Enzyme Catalase in Celery Tissue Alters the Rate of Reaction with Hydrogen Peroxide.

    Like all globular proteins, enzymes possess hydrophilic R groups, the group which varies in different amino acids and determines their characteristics. H R GROUP O All amino acids (which join to form proteins) have a central carbon \ | // with an amine group (NH2) and a carboxylic acid group (COOH). N - C - C The only thing which differs is this R group and it thus determines / | \ the characteristics of the amino acids which make up the protein or H H OH enzyme.

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  19. Experiment to investigate the effect of temperature on protease enzyme

    Im am carrying out this experiment to see how enzyme action is affected by temperature on a microbial protease enzyme. I will observe how and if temperature affects how quickly the enzyme works on removing the silver salts from photographic film. The protease enzyme breaks down a layer of gelatine on the film that holds the silver salts to the actual film. I predict that with the increase or decrease of temperature of the enzyme, its working time will increase or decrease accordingly, showing a peak temp.

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  20. To investigate one of the factors that affects the permeability of cell membranes.

    The higher the temperature, the more the membrane will be damaged, and therefore the more the amount of pigment which leaks out. You can measure the permeability by seeing how dark the surrounding water is, or by measuring the amount of light which will transmit through. As the permeability increases and more pigment leaks out, the surrounding water will become a darker red, and the amount of light that will transmit through will decrease because there are more pigment molecules in the way.

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  21. Investigating the rate of reaction of enzymes at different temperatures in the clearing of photographic film.

    * Fill a test tube with 20ml of the enzyme and place in the water bath. * Using the thermometer check that the enzyme is at the same temperature as the enzyme * When it is place the photographic film in the test tube with the enzyme and start the timer * Check the photographic film every 30 seconds by lifting it out by the wire. When you can see that the photographic film has gone completely clear stop the timer. * The time you have is the time it has taken for the enzyme to break down the protein.

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  22. Enzyme investigation

    Due to the presence of oxygen the beads will rise. We will comment on how our chosen variable affects the rate of the reaction. To find out how temperature affects the speed in which the catalyse reacts with the hydrogen peroxide solution, we're going to use, 10ml of the solution, and will be carrying out the experiment at 5 different temperatures, these being- 20(c, 30(c, 40(c, 50(c and 60(c. We will heat up the water to our desired temperature in a water-bath, and will add 1 yeast bead, using a stopwatch we will time the speed of the reaction.

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  23. Discuss the mechanisms responsible for polarity acquisition in lateral organs of plants. What evidence supports your views?

    Through histological analysis the SAM can be divided up into three distinct regions based on cytoplasmic densities and cell division rates: the peripheral zone (PZ), the central (CZ) zone and the rib zone (RZ) (figure 1). Lateral organs are created from tissue in the peripheral zone, stem tissue is derived from the rib zone and the central zone is responsible for replenishing the cells used in the peripheral and rib zones. The SAM is also comprised of three clonally distinct cell layers.

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  24. The effect of temperature on an enzyme controlled reaction

    The catalase is only efficient in decomposing hydrogen peroxide because it is able to do it very quickly - one catalase molecule can deal with six million molecules of hydrogen peroxide. The catalase is able to keep the hydrogen peroxide levels low and safe. When the catalase enzyme has catalysed the H2O2 substrate the end products are merely water and oxygen. For the experiment I will use yeast as the source of the enzyme catalase to catalyse the hydrogen peroxide.

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  25. Stem Cells

    Adult stem cells are also found throughout the body in the skin, brain, bone marrow, and blood (15). But unlike the embryonic stem cells, adult stem cells have limited potential to multiply and grow into other types of tissues. The Bush Administration stands in the middle of all the controversy, not having stated very clearly whether it believes stem-cell research is ethical or not. Current law forbids the use of government funds for research on human embryos or embryonic stem cells ("A Ready-Made Controversy" 10). Furthermore, government research is limited to the 64 existing stem cell colonies (Southwick A26).

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