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AS and A Level: Molecules & Cells

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  1. The Hostage

    I feel extremely cold but I dare not move because I don't know what these sick twisted people will do to me next. My mind reverted back to memories of my wife and my childhood. I tried to recollect what my wife looked like but I had been confined for so long now it was all just a blur. I also thought of how we used to sit down at the table on Sundays with the smell of chicken roasting in the oven.

    • Word count: 785
  2. Infertility Treatment Brochure

    There are other reasons why a woman's infertile, but they aren't as common. A woman could not ovulate because of lack of FSH (an essential hormone for pregnancy). She could also simply not have egg cells in her ovaries, this wouldn't allow the woman to conceive naturally but it is very rare Male Infertility: When it comes to men, one should concentrate in their sperm cells. The amounts produced and their health state is crucial. Hundreds of millions of sperm cells are produced in an average male, if your sperm cell production is bellow 20 million sperm cells per cm3, then it will begin to affect fertility.

    • Word count: 784
  3. Investigating the Effect of Temperature on Enzyme Activity

    Repeat steps 1-4 again for the following temperatures: 25�c, 35�c, 45�c and 55�c. Risk Assessment: * Hydrogen Peroxide (H2O2) is an irritant and dangerous if swallowed. * Wear eye protection. * Avoid contact with skin and clothes. Results: Temperature �c Rate at which the oxygen evolved in cm3per min-1 Mean Rate 1 2 3 15 0.6 0.2 No result 0.4 25 2.2 2.6 No result 2.4 35 2.6 2.5 2.6 2.6 45 2.0 1.8 2.2 2.0 55 1.0 1.0 No result 1.0 Graph: Analysis of results: The graph and table of results both prove the hypothesis to be correct: The higher the temperature, the faster the reaction rate, until an optimum temperature is reached.

    • Word count: 741
  4. Objective: To investigate the factors which affect the production of yoghurt

    In this practical, we investigate some of the factors that affect the production of yoghurt. Bacteria in the starter culture ferment milk sugars to produce organic acids, such as methanoic and lactic acid, and consequently the pH will fall. The rate of change in pH can be used to indicate the rate of formation of yohgurt. Materials: UHT milk, natural yogurt to use as a starter culture, boiling tubes, pipettes, syringes, cling film, glass stirring rod, pH paper, water bath.

    • Word count: 973
  5. The effect of stress on beet cell membrane

    Tube number three will register a 5. Tube number two will register an 8. And finally tube number one will register a 10. I am studying an organism of the plant kingdom a Beta Vulgar-is. We are going to determine the effects or damage that temperature has on beet cell membranes. We will be able to tell how much effect the said temperature has on the organism by the amount of betacyanin affected and released by the organism. Method: All degrees being in Celsius. A beet was acquired and cut into six equal pieces measuring approximately 2 mm by 1 mm by 1 mm.

    • Word count: 677
  6. Digestion report

    then suspend it over the Bunsen burner, using the tripod stand and the gauze 3. boil the water until it is about 35�C 4. fill test tube A with 2 ml amylase and place it in the beaker for 3 minutes 5. add to the test tube 5 ml of starch and leave the solution in the beaker for another for 10 minutes 6. pour some of the solution out onto Petri dish A 7. add five drops of iodine and gently stir 8. record the solutions color 9. repeat steps 1-8, changing the temperature to 40�C, with test tube B 10.

    • Word count: 687
  7. Are mobile phones more of nuisance than a benefit?

    Similarly, even through average cell phones we can store thousands of our favorite musical tracks, many videos and listen and watch them whenever we like. So, recent cell phones are computer, walkman, TV, MP3 player and camera, all in one in a tiny device, bringing joy and effectiveness in our personal and business lives.-118 Likewise, satellite phones make us able to contact every phone user wherever we are on the surface of the earth be it at Antarctica in the South, Arctic circle in the North, Amazon rain forests in Brazil or the Mount Everest in Nepal.

    • Word count: 865

    contained different active ingredients with different active rates within the concentration affecting the overall activity of both enzymes making the comparison harder to see with each other. The overall experiment could of been more and reliable accurate if further tests were done, like mentioned in the conclusion, there was a limiting amount of pH buffer solutions used. There was not equal amounts of basic pH compared to acidic pH so the graphs would prove that it is ambiguous as it is impossible to tell the optimum pH for either of the amylases.

    • Word count: 534
  9. What are cells?

    These proteins include enzymes, receptors and antigens. Proteins can be, amongst other hormone binding sites, enzymes, or pumps for active transport. Some membranes also include the composition of the glycolax. These are glycoproteins and glycolipids whose functions are cell-cell recognition, as receptor sites for chemical signals such as hormone messengers and assisting in the building together of cells to form tissues. Membranes are fluid mosaic because the whole structure that is lipids and proteins is on the move and are called mosaic because the proteins are scattered.

    • Word count: 965
  10. Factors Affecting Enzyme Activity.

    There are four main factors affecting enzyme activity:- 1. Temperature: enzymes work best at an optimum temperature. Below this, an increase in temperature provides more kinetic energy to the molecules involved. The numbers of collisions between enzyme and substrate will increase so the rate will too. Above the optimum temperature, and the enzymes are denatured. Bonds holding the structure together will be broken and the active site loses its shape and will no longer work. 2. pH: as with temperature, enzymes have an optimum pH.

    • Word count: 870
  11. mitosis. Interphase is made up of phases: G1, S phase, and G2. The G1 and G2 phases are checkpoints for the cell

    * G1 stands for gap 1, or presynthesis; S for synthesis; G2 for gap 2, or postsynthesis. * M is the mitotic division phase. * chromosomes are replicated during the S (synthesis) phase of the cell cycle before mitosis can begin. Mitosis: -- Mitosis is the process where one set of chromosomes is equally dividing into two identical groups. The new "daughter" cell has exactly the same number of chromosomes and information as the "parent" cell. 1 cell divides and becomes 2 cells. Prophase: The chromatin, diffuse in interphase, condenses into chromosomes. Each chromosome consists of 2 chromatids .

    • Word count: 783
  12. Enzymes/Enzymes are globular proteins. This means that they are made up of

    This involves lowering the activation energy. So that the enzyme and substrate can collide successfully with lower kinetic energy (so reactions will work at fairly low temperatures), and enzyme substrate complexes will form so a reaction will occur. How do Enzymes Work? For a reaction to work molecules must collide successfully with enough energy, known as the activation energy. The greater the kinetic energy molecules have, the greater the chances of a successful collision and therefore the greater the rate of reaction will be.

    • Word count: 885
  13. physiology test

    It travels in saltatory fashion along unmyelinated axons. B. It travels by the diffusion of Na+ ions through the cytoplasm. C. It does not go anywhere; it generates passively spreading depolarizing currents that trigger another action potential farther along the membrane. D. It travels by depolarizing glial cell ????? ~~ of all the things iv lost i miss my mind the most~~ says: E. It serves as the source of currents that increase the resting charge on adjacent membrane ?????

    • Word count: 579
  14. investigating the enzyme pectinase

    This means adding pectinase to your fruit pulp means you can extract more fruit juice. Pectinase is defined as a biological catalyst so it will also speed up the reaction as well as causing more juice to be produced. A number of factors can affect the rate at which an enzyme works for example these can be concentration, temperature and the ph. The PH levels can affect the rate at which the enzyme works, if the level is too acidic or alkaline the 3D shape of the enzyme is altered because the conditions are too corrosive for it to keep its shape.

    • Word count: 903
  15. Investigation on how the concentration of ethanol would affect the plasma membrane in a beetroot cell

    6 cuvettes A colorimeter Method: > Before doing the experiment, apron and safety specs should be wearied. > First of all, I need to cut my beetroot into cylinder shapes using a cork borer > Then I need to cut the cylinders of beetroot into 25 5mm slices. > After that, I need to rinse the beetroot cells several times until the purple colour is washed away. > Place 5 slices of beetroot cells into 5 different cylinders > The total volume of the solution is going to be added to 25ml > For the distilled water one, use a syringe to add 25ml of distilled water in a cylinder.

    • Word count: 785
  16. Aim: To investigate the ideal conditions for enzyme action

    If however it is too cold the enzymes will not have enough energy to react. pH: The pH in the stomach is usually acidic, only the enzymes used to this pH will be able to react in these conditions. Surface area: The surface area is important because the larger the surface area the more enzymes can act on it, which makes it easier and quicker to break down the food. Amount of food used: The bigger the size of the food (if the same amount of enzymes are acting on it)

    • Word count: 934
  17. The effect of enzyme concentration and enzyme activity

    Method and Materials To carry out this experiment we used: * Funnels (same Width) * Beakers * Pepsin * pH Buffer * Stopclock * Gelatine Instructions 1. Place a funnel securely using a clamp stand, overhead a beaker 2. Add 10cm3 of Pepsin to 7 Test Tubes 3. Add 3 cm3 of pH buffer to each of the above 7 test tubes 4. Mix well, and pour into the gelatine trays and mix the gelatine, using a string rod, for 15 seconds 5. Pour the gelatine down the funnel and start the stopwatch and record the time taken for all the gelatine to pour into the beaker 6.

    • Word count: 592
  18. Cell membrane

    In animal cells the plasma membrane alone establishes a separation between interior and environment, whereas in fungi, bacteria, and plants an additional cell wall forms the outermost boundary. However the cell wall plays a mechanical support role rather than a role as a selective boundary. The plasma membrane is only about 10 nm thick and may be discerned only faintly with a transmission electron microscope. One of the key roles of the membrane is to maintain the cell potential. Phospholipid molecules in the cell membrane are "fluid," in the sense that they are free to diffuse and exhibit rapid lateral diffusion.

    • Word count: 711
  19. Biology Assignment

    Lock and Key theory * Either a single molecule with a complementary shape, or more than one molecule that together have a complementary site can fit into the active site. * These substrate molecules form temporary bonds with the amino acids of the active site to produce an enzyme substrate complex. * The enzyme holds the substrate molecules in such a way that they react more easily.

    • Word count: 433
  20. Evaluation of effect of temperature on beetroot cell membrane experiment Most of the results of the experiment weren't anomalies

    After that, I would square the deviation by the mean. I do however recognise various limitations of the experiment which could reduce the reliability of the findings. Limitation 1: The cuvettes could have fingerprints or scratches on them. If this is the case then the results will be a much higher absorbency rate i.e the light won't be able to travel through the fingerprints or scratches as easily so the solution will be treated as being darker (and having more betacyanin)

    • Word count: 746
  21. Describe what happens to saccharide units in starch when taken in by the mouth for digestion until the assimulation into muscl

    Most of the important polysaccharides are made from hexose units, so are called hexosans. Many are made from glucose itself. So are called glucosans. Glucose units can from long chains in three ways. Amylose and cellulose are completely straight. Starch is a mixture of both amylose and amylopectin. Glycogen is amylopectin with very short lengths between its branches. Digestion involves the breakdown of large, insoluble food molecules into smaller, soluble compounds, which can be absorbed. For example, starch is broken down into smaller monosaccharides and disaccharides; proteins are broken down into polypeptides, then into tripeptides, dipeptides and finally amino acids.

    • Word count: 539
  22. An investigation into the effect of temperature on the activity of enzyme catalase.

    Used ice bath to take these tubes to the required temperature under the room temperature. Boiled a beaker of water and used it as water-bath to achieve the required temperature more than the room temperature. These temperature were 1, 10, 29 (Room temperature), 45 and 60. Filled another test tube with water which it will be used for counting the bubbles. Once the required temperature was achieved, 5 disks of potato (each cut to 2mm) were added to test tube. Attached the delivery tube to the tube with hydrogen peroxide and potatoes and the end of delivery tube was in the tube filled with water earlier (Figure 1).

    • Word count: 698
  23. Onion cell and cheek cell IntroductionTo stain the cells so the parts of the cell such as the nucleus are marked out and then it can be viewed

    We don't use the sun because it is too powerful, and if the naked eye looks at the sun for too long, the retina can be burnt. I should place the microscope in the middle of the table so that it doesn't slip off the sides. Make sure the lamp is away from anything that can be burnt.

    • Word count: 494
  24. An investigation into the effects of temperature on the enzyme renin.

    Enzymes can be temperamental and can be denatured easily if conditions are wrong. This can be for various reasons. pH levels are important to enzymes they need to be kept at an optimum level to insure they survive. If the pH level is to high or low this will cause the enzyme to become denatured and if the temperature is to high or low this will also have the same effect of denaturing. Hypothesis In my prediction for the experiment I would expect to see that once the milk is heated at a low temperature and the renin is added that it will take some time for the reaction to place.

    • Word count: 985
  25. Benedict's test

    6. Repeat the procedure from 4 to 6 until all of the specimen had boil and record the changed of the solution's colour. Results 7. Record the result in a table 8. Read off the result. The solution's colour is changed if reducing sugar present in the food. The solution's colour turns through from blue to green, yellow and orange to brick red. 9. The colour can determine the concentration of sugar in each food. 10. If the food doesn't present reducing sugar, the solution remains blue.

    • Word count: 567

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