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AS and A Level: Molecules & Cells

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  1. Why is Aspirin the greatest discovery ever?

    Hoffmann added a chemical called acetyl chloride to combat the effects on the stomach to salicylic acid. He also found a more effective way of producing salicylic acid by extracting it from a plant called 'spiraea ulmaria' which gives the 'spir' in aspirin. Hoffmann then patented aspirin in 1900 and sold it in powder form. Therapeutic Uses Aspirin is known as a miracle drug because it can treat a variety of illnesses and prevent life-threatening heart attacks or strokes. Aspirin was originally used as a pain relief drug but then also found to treat cardiovascular disease, arthritis, fever, colds and brain haemorrhage.

    • Word count: 1358
  2. Investigation on a ripening banana to indicate the biochemical changes to make it sweet.

    The banana stored for 5 days should show negative result of iodine test and positive result of Benedict's test. Materials and apparatus: Banana stored for 1 day Banana stored for 3 days Banana stored for 5 days Benedict's solution Iodine solution 50-ml beaker 250-ml beaker 10-ml measuring cylinder 1-ml pipette 5-ml pipette Mortar & pestle Electronic balance 1 pc. 1 pc. 1 pc. Shared Shared 1 1 1 2 2 1 set Shared Spotting tile Razor blade Test tube Test tube rack Dropper Glass rod Label Distilled water in washing bottle Safety spectacles Muslin cloth Bunsen burner, tripod, wire gauze, lighter & insulation plate Shared 1 10 1 2 1 1 1 6 1 set Procedure: (a)

    • Word count: 1900
  3. Growing Bacteria collected from surfaces and observing the results.

    I even found out that hand sanitizer can work against the culturing of E-coli. Hypothesis: If I whip a common surface then I can culture bacteria. I did this because I was curious to find out how much bacteria is on a common surface. I believe I would find this out by doing this experiment because I will see how much bacteria will form and what it would smell like. I think if it smells really bad and grows a lot and very fast then it is a toxic bacteria.

    • Word count: 1127
  4. Write about the Transport across Plasma membranes

    20% of lipids in the cell membrane are cholesterol, which adds strength to the cell. The rest of the lipid is full of glycolipids, which are extrinsic on the cell surface membrane; this 'gylcocalyx' acts as a recognition site of cholera toxins. All of the lipid molecules give the membrane fluidity as they can move sideward's and help in the exchange of substances. There are two types of proteins embedded into the phospholipids bilayer in different ways: some are extrinsic proteins, which occur on the surface of the bilayer and do not extend completely across the membrane, and there are

    • Word count: 1062
  5. In my experiment I will discover how much vitamin C there is in fruit juices and fresh fruits and if there are any differences and why they are there.

    I secondly added Fruit Acid (fruit juices-vitamin C) in, 2 drops at a time from the pipette. (The pipette was filled to 1cm3 of Fruit Acid each time), and I then shook the test tubes to dissolve the acid juices into DCPIP, I did this until the DCPIP changed from its blue colour to an almost see through colour and measured how much acid was left in the pipette and collected the results in a table (below). Hypothesis I think that the fresh fruit juices will contain more vitamin C than the fruit juices. I think that the Orange fruit will have the most vitamin C and the lemon juice having the least.

    • Word count: 1208
  6. pH and Its Affect on Enzymes

    The liver providing the catalase we tested with are from a cow, so the enzymes shouldn't be too much different from a human's. The function of catalase in its most simple form is to break down H2O2 (Hydrogen Peroxide). Catalase breaks H2O2 down into two elements, H20 (water) and O2 (Oxygen), which is the bubbling that takes place when you pour hydrogen peroxide on a cut. An identifying factor of enzymes is their malleability, in order for enzymes to do their job they must bind to a specific molecule and stress the molecular bonds of that molecule in order to make the objective result more likely.

    • Word count: 1547
  7. Human Cloning

    Specially, "Is human cloning right or wrong?" remains a big thorny question for scientists. 1) What does "clone" mean? The word "clone" is both a verb and a noun. As a verb, it prefers to the process of creating a clone. Two different processes can produce clones: embryo splitting, the rare, but naturally occurring event that produces identical twins, and nuclear transfer, the technique was used to create Dolly. As a noun, "clone" is an exact copy of a plant or an animal that made by removing one of its cells. The term "human cloning" means the creation of a genetically identical copy of a human, human cell or human tissue.

    • Word count: 1925
  8. Which antibiotic is most effective?

    Wash your hands with the bactericidal soap. Spray the working area thoroughly with the disinfectant spray and wipe with a paper towel after waiting for the disinfectant to act. 2. Prepare an agar plate seeded with bacteria. This may have already been done for you. If not, follow the instructions on the Student sheet 'Pouring agar plates' which can be found with Activity 4.19. Label the Petri dish on the base at the edge with your name, the date, and the type of bacterium it is inoculated with.

    • Word count: 1041
  9. Cervical Cancer Vaccine. I decided to speak to a professional to obtain their opinion on the Cervical Cancer vaccine. I contacted my local surgery and spoke to one of their doctors.

    in the UK are infected with the HPV virus at some time during their lifetime. How does the virus cause cancer? The virus gets into the surface cells of the cervix where it can stay for several years without causing any harm. Then, and for no apparent reason, it may start to cause damage to these cells.[2] Doctors have introduced the Cervical Cancer Vaccine and alternative solutions such as getting regular Pap smear tests to reduce the number of deaths from Cervical Cancer per year. A possible Solution - Cervical Cancer Vaccine The Cervical Cancer vaccine was developed to prevent certain types of cervical cancer and pre-cancerous abnormalities in women.

    • Word count: 1780
  10. The aim of this practical is to investigate on the different amounts of Vitamin C in a variety of juices and research on how it is affected when stored in its natural state or diluted.

    were also included in order to carry out the practical. Structure of Ascorbic acid Vitamin C can be separated into two main groups which are (Water-soluble and fat-soluble vitamins) these are mainly made up of vitamins C and B. Lack of vitamin C can lead to Scurvy, a common deficiency which causes muscle weakness, swollen and bleeding gums. Milder symptoms include tiredness, depression and bleeding under the skin which means wounds don't heal as quickly as they should. Lack of Vitamin C can be treated through having a balanced diet and eating enough fruits (oranges, especially)

    • Word count: 1669
  11. The structure and function of Carbohydrates

    The difference between alpha and beta glucose is the differentiation of the side groups at C1. Glucose has many functions in the body. It is the main respiratory substrate used both in aerobic and anaerobic respiration. Aerobic respiration is the release of energy as a result of a series of reactions that break down glucose in the presence of oxygen. Anaerobic respiration on the other hand occurs in the absence of oxygen where only glycolysis occurs and glucose is broken down into pyruvate. In the two processes ATP is released which is an immediate source of energy for chemical reactions.

    • Word count: 1029
  12. The effect of Temperature on membrans

    I believe that because the membrane of plant cells is made up of a lipid bilayer. This includes a layer of phospholipids which are arranged in a hydrophobic structure. This allows the proteins to have full control over which molecules can pass through the membrane. Due to the temperature change, it may experience change in its structure and therefore, I believe that the higher the temperature it is, the more effect there will be on the membranes of the beetroots.

    • Word count: 1240
  13. Germination Inhibitors

    From the mean values of the group results, I have recorded the following data: Mean Standard Deviation Standard Error 95% Confidence Limit Day 1 1.78 9.90 4.43 1.78 � 8.68 Day 4 11.27 129.73 58.02 11.27 � 113.72 Tomato Juice Concentration 0% 14.96 182.18 91.09 14.96 � 178.54 Tomato Juice Concentration 100% 0.98 1.93 0.97 0.98 � 1.90 On day 1, the seeds have just begun germinating and therefore the set of results are lower than day 4. However, the 0% tomato juice concentration remains the concentration which induced the most germination of lettuce seeds, having the mean total of 7.81, compared to the mean value of 0 for 100% tomato concentration.

    • Word count: 1246
  14. The Environmental Issues Associated With Agricultural Chemicals

    However, through the usage of pesticides, the population of aphids are controlled, and the yield of crop remains undamaged. Additionally, a disadvantage to the use of pesticides is the development of resistance, which is another environmental concern, where gene mutations in insects have helped them to become resistant to DDT (3). Therefore, the overexposure of the insect population to DDT enabled the resistant strain to be selected, and eventually, the whole insect population had become resistant to that particular type of insecticide; DDT is now useless. The resistance of one type of pesticide means that in order to extinguish the pest is harder, and more powerful amounts of pesticide is needed to overcome the entire population, which increases in growth as the resistance strengthens.

    • Word count: 1037
  15. Biology AS Planning Exercise Jan 08.

    The shape of the active site is specific to the substrate molecule. When the substrate molecule collides with the active site an enzyme-substrate complex is formed. The substrate is broken up into smaller products. Reference 1 At low temperatures the substrate molecules have very little kinetic energy so they move very slowly. This slow movement means that the substrate molecules are less likely to collide with the active site and so the rate of ripening will be slow. Reference 1 As the temperature increases so does the kinetic energy. At this point the substrate and enzyme molecules vibrate energetically and there is more chance of the enzyme and substrate colliding therefore increasing the rate of reaction and moreover the rate of ripening.

    • Word count: 1155
  16. Free essay

    Life on Mars and Moon - biologically possible

    Let's examine technically, financially and biologically the possible life on the moon. Financially it would cost about a trillion just to make an effort to build a base. Firstly we will have to improve our transport means, which are obviously too bad (it is well known fact that no one has stepped on the moon for decades due to very strange reasons). So we will not settle on the moon in next 2 or 3 centuries. Let's see if it is worth making efforts.

    • Word count: 1273
  17. Free essay

    Explain the relevance of each different method of transport across membranes in the regulation of water levels in mucus

    The Chlorine pump transports Chlorine across the basal membrane into the cell so that there is no shortage of Chlorine ions inside the cell when they diffuse through the CFTR channel. The pumps are relevant for regulation of water levels in the mucus because they are able to transport ions against concentration gradients and are therefore important for keeping a stable amount of ions in one place at any time. They are not, however, as important as the channel proteins, because if there is a faulty channel protein, Cystic Fibrosis happens.

    • Word count: 1223
  18. The Effect of Age on Short Term Memory

    This is the 'control centre', which coordinates the body's functions. The brain is a cream-coloured organ, Surrounded and protected by the bones of the cranium and also by three membranes known as meninges, which are between the surfaces of the brain and the skull. These membranes help to secrete cerebrospinal fluid. This provides protection and cushioning of the brain and also fills the spaces inside it, known as ventricles. Like every other organ in the body, the brain is made up of cells. There are about 40 billion nerve cells, known as neurones, within the brain.

    • Word count: 1696
  19. Scientific theories -prokariotic origins of mitochondria and chloroplasts

    Mitochondria and chloroplasts have quite a few more similarities with prokaryotic cells than eukaryotic cells like, the nuclear envelope is absent in prokaryotic cells and these organelles where in the eukaryotic cells it is present. These organelles have single circular chromosomes the same as prokaryotic cells where in eukaryotic cells they have multiple, linear which are wound on nucleosomes. The Golgi apparatus is present in eukaryotic cells and absent in prokaryotic cells and these organelles. The ribosomes for prokaryotic cells are relatively small like mitochondria and chloroplasts whereas they are relatively large in eukaryotic cells.

    • Word count: 1000
  20. The objective of this experiment is to determine the effect of temperature to the activity of enzyme.

    Moreover, a control set-up should be readied by preparing the mixture of acetate buffer and starch solution without amylase. Requirements: Materials: - Green beans (20g) - Peptone solution (10cm3) - Starch solution (15cm3) - Acetate buffer (10cm3) Apparatus: - 1 electronic balance - 1 Centrifuge - 2 strong perspex tubes (used in the centrifuge) - 1 Measuring cylinder (10cm3) - 1 Glass rod - 1 Stop watch - 2 droppers - 1 spot tile - 2 boiling tubes - 3 test tubes - 1 mortar and pestle - 2 beaker Procedures: (Since the time was not enough to do the whole experiment for each group, only one temperature of the mixture was done by different groups.)

    • Word count: 1887
  21. Human Awareness Essay

    Drugs such as erythropoietin and growth hormones are naturally produced in the body. As technology advances, drugs have become harder to detect because they mimic natural processes so closely. When technology advances to a stage where drugs are undetectable and the risk of being caught cheating is zero, athletes may chose to cheat to win. Drugs are against the rules, but we define the rules. If drugs are made legal and freely available, that would eliminate one form of cheating.

    • Word count: 1190
  22. Proteins - structure and functions

    The other 8 must be obtained from diets. Amino acids bond to form proteins. They are joined by peptide bonds. The reaction in which this happens is a condensation reaction and includes the formation of a water molecule. A peptide bond is a covalent bond between the 2 amino acids. Hydrolysis the breaking up of the peptide bond to leave amino acids free. When 2 amino acids bond, a tripeptide is formed as the 2 amino acids become joined by a peptide link and when 3 amino acids bond, a tripeptide is formed, which has 2 peptide links.

    • Word count: 1265
  23. Investigation to find out what effect changing the concentration of calcium ions has on the rate of coagulation of milk

    Para-kappa-casein does not have the ability to stabilize micelles and so the calcium-insoluble caseins precipitate, forming a curd. Calcium ions are required to activate the enzyme rennin. These ions are removed by precipitating them as calcium citrate. Na3C6H5O7(aq) + Ca2+(aq) --> NaCaC6H5O7(s) + 2Na+(aq) Inorganic ions such as metal ions can act as cofactors. The ion combines with either the enzyme or the substrate to reduce the activation energy. These ions are called activators. Activators make the enzyme substrate complex form more easily. Ca ions are a cofactor for rennin, so they assist in forming the enzyme-substrate complex by moulding either the enzyme or substrate into a more suitable shape; in this case they mould the enzyme rennin.iii

    • Word count: 1311
  24. food groups present in chemcial testina

    If no lipids were present, the solution would remain clear, with no droplets forming. Lipids have a variety of functions in all living things. For example, they provide thermal insulation as well as mechanical protection for organs such as the heart and kidneys. As most lipids are insoluble in water, they provide a protective waterproof barrier on things such as skin, feathers and plant leaves. Lipids are also a good storage of energy, providing 9 calories per gram. In comparison to the structure of lipids and carbohydrates, protein molecules vary in size and structure.

    • Word count: 1479
  25. An experiment into looking at cell division in a garlic root tip

    The second stage is prophase, the nucleolus disappears and the chromosomes become more visible. The centrioles begin to move at opposite ends of the cell and the spindle fibers being to form. Spindle fibers are a collection of microtubules attached to a centromere during mitosis, which are responsible for the movement of the chromosomes to opposite poles. (http://en.mimi.hu/index.html) The third stage is metaphase. Here the chromosomes are beginning to arrange themselves on the equator and the chromatids (an exact copy of one half of the chromosome) being to dram apart at the centromere region (a region of the chromosome, where two identical chromosomes are attached to a spindle fiber).

    • Word count: 1007

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