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AS and A Level: Genetics, Evolution & Biodiversity

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  • Marked by Teachers essays 33
  • Peer Reviewed essays 15
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  1. Marked by a teacher

    An Investigation into the Mitotic Nuclear Division of Allium Sativum Root Tip Cells, and the Relative Duration of Each Phase of this Cellular Cycle

    5 star(s)

    In this investigation, it is believed that the durations of each phase in the process of mitotic nuclear division vary, for the following biological and biochemical reasons. Stage B: Prophase: 20 relative time units Prophase is the cellular cycle stage of mitosis in which chromatin condense into a highly ordered structure called a chromosome (7, 8). Since the genetic material has been duplicated, there are two identical copies of each chromosome in the cell. The other important cellular organelles in the prophase stage are the centrioles (1).

    • Word count: 8293
  2. Marked by a teacher

    MENTAL HEALTH

    4 star(s)

    Mental health is linked to behaviour Mental, social and behavioural health problems could interact and have a large effect on an individual's behaviour and well-being. These following examples could have effects on an individual's behaviour and well being and could cause them to find it very difficult to cope, these are as follows: Substance abuse, violence, and abuses of women and children, health problems such as heart disease, depression, and anxiety. (www.who.int) What is mental illness? A mental illness is a health problem that significantly affects how a person feels, thinks, behaves, and interacts with other people.

    • Word count: 11946
  3. Marked by a teacher

    Epping Forest Coursework

    4 star(s)

    Samples will be used to identify which brackens have a tall height in relation to its area or variables, which area listed below. The statistical test that I will use to interpret these data is the 'Mann-Whitney U' test. This is used to calculate the medians of the two sets of data collected (one from the light and one from the dark area) and would show if the difference in height between the areas is significant or not. This will be used to measure the strength of the relationship between two variables.

    • Word count: 8458
  4. Marked by a teacher

    Nature vs. Nurture - And its affect on intelligence, personality, and behavior

    4 star(s)

    Evaluation of Sources Nature vs. nurture has been an oscillating controversy in the field of psychology for many years. Does one inherit genes, or are one's genes affected by the environment? This question has been the focal point in the field of psychology for decades. As more and more case studies are coming out with results, a clearer picture comes into view. The "picture" portrays how the blend of both nature and nurture affects human growth and development. The basis of nature is the principle that people have their personalities engraved inside their genes, which are inherited by their parents.

    • Word count: 3331
  5. Marked by a teacher

    The Problem of Endangerment in Siberian Tigers

    3 star(s)

    An estimation of forty Siberian tigers in the wild in 1940 led the former Soviet Union to place the Siberian Tiger on the endangered species list. Poaching became a problem again in 1990 when the economy of Russia collapsed3. Poaching in Siberian tigers has led to: * Population of Siberian tigers decreasing, * Demand of Siberian tiger pelage high (causing poaching to increase)2, * Siberian tigers to lose habitat (their habitat is not safe anymore), * Offspring to become scarce (cubs will not be able to survive without parent); * Low survival rate in wild caused by Siberian tigers to become domesticated when forced to be used as a pet by local humans.

    • Word count: 3025
  6. Marked by a teacher

    The daphnia lab report

    3 star(s)

    Caffeine abuse causes palpitations, tremors, diarrhea, nausea, chest pains, sweating, vomiting and neurological symptoms. Addicts develop tolerance for caffeine and require a higher dosage every time to achieve the desired effects (Hasan 24). Early studies showed that high levels of Caffeine made the heart beat abnormally fast and constricted cerebral blood vessels in the human brain. Therefore, if a caffeine addict decided to stop drinking coffee for a day, their blood vessels would dilate resulting in a powerful headache. Other symptoms include fatigue and melancholy when withdrawing from caffeine (Caffeine). Caffeine's sensitivity varies from human to human but high levels of caffeine isn't good for the human body, as it is linked to restlessness, insomnia, anxiety, stress, heart irregularities and an increase in blood pressure.

    • Word count: 3009
  7. Peer reviewed

    An Investigation into the effect of caffeine on reaction times

    5 star(s)

    Reduced adenosine activity also contributes to increased dopamine activity5, a neurotransmitter which is a precursor in the production of epinephrine6. Together, these effects increase the levels of epinephrine in the brain. ADHD (attention-deficit hyperactivity disorder) is caused by a deficiency in dopamine, and its treatments raise dopamine levels7. This suggests that dopamine also plays a part in attention and concentration. Synapse showing antagonistic action of caffeine on adenosine receptors - http://www.snabonline.com/pupil/mediabank.aspx -> Book artwork with no labels -> Figure 8.57 - 22/10/08 As well as blocking adenosine receptors, caffeine also blocks the removal of cAMP (cyclic adenosine monophospate) from cells.

    • Word count: 4449
  8. Peer reviewed

    The cloning of Dolly.

    4 star(s)

    Cloned animals will be living in factories that would be able to produce a range of human drugs to helps us with various illnesses and maybe even diseases. The purpose of cloning Dolly was to see if the idea of a different way to producing animals, would actually work. Cloning mammals means that you can use larger animal types. Definition of terms What is cloning? Cloning is the production of genetically identical animals or humans using laboratory-grown cells. The term cloning (derived from the Greek word klon, meaning "twig")

    • Word count: 4230
  9. Is Golden Rice the Solution to Vitamin A Deficiency in the developing world? The purpose of this article is to look at the argument of the introduction of GM crops, which are more resistant to disease and can be nutritionally enhanced to combat the diseas

    Red is most severe (clinical), green least severe. Countries not reporting data are coded blue. What is VAD? VAD affects vision by inhibiting the production of rhodopsin, the eye pigment responsible for sensing low light situations. Rhodopsin found in the retina is composed of retinal (an active form of vitamin A) and opsin (a protein). As sufficient amounts of Rhodopsin cannot be produced by the body, a diet low in vitamin A will ultimately lead to reduced amounts in the eye. This causes the cells of the eye to die which accumulate on the conjunctiva leading to infection and possibly blindness.2 One answer to sustainable vitamin A delivery system is the use of Golden rice.

    • Word count: 3050
  10. Biology Coursework: Does Acupuncture relieve pain?

    It may also trigger neurotransmitters and neurohormones, which influence such dynamic systems as circulation and the immune response. Acupuncture Studies Dr Bruce Pomeranz - Animal Trials Bruce Pomeranz, a neuroscientist from the University of Toronto in Ontario, discovered in 1976 that acupuncture works as an analgesic, triggering the release of endorphins - the body's natural painkillers.4 He found that mice could tolerate pain more easily after acupuncture, and that he could block the analgesic effect by injecting the mice with naloxone before applying the needles - the substance prevents endorphins binding to nerve cells. He believes that when the needle is inserted into the muscle, it stimulates small nerve fibres which in turn send impulses to the mid-brain and hypothalamus.

    • Word count: 3855
  11. HSC maintaining a balance notes

    Others without these die out. Divergent Evolution: one species evolving into many species as a result of selective pressures and adaptation to different environmental conditions. Finches in Galapagos Islands - each island had different conditions and isolation meant no interbreeding so they adapted and overtime became new species. Convergent Evolution: organisms that are not closely related evolve similar traits as they adapt to similar environments. Shows that similar environmental characteristics allow individual with genetic advantage to survive and reproduce. Aus.

    • Word count: 3630
  12. Parkinsons Disease

    In the long term PD will ultimately lead to death. Causes We are still unsure of the causes of PD but here are the most likely and most talked about suggestions: 1. The hereditary form of PD occurs in fifteen per cent of cases2. The genes affected help clear nerve cells of excess proteins. Scientists are not sure but it is thought that when the 'production process for protein manufacture breaks down, little clumps of ill-formed proteins begin to accumulate in cell' 17, causing cell death.

    • Word count: 3857
  13. Can relapse in acute lymphoblastic leukaemia (ALL) be prevented?

    Some of the symptoms include... > Anemia - caused by excessive leukemic cells preventing the production of healthy red blood cells. Symptoms of anemia include fatigue and breathless. > Fever (high temperature) > Weight loss > Frequent infections that take long to fight off - due to the lack of health and fully developed white blood cells > Bruising easily and with no obvious cause - due to reduced number of platelets > Bleeding from the gums or nose - sensitive as blood can't easily clot with reduced platelet count.

    • Word count: 4515
  14. An Investigation into the effect of flow rate on the size of Gammarus pulex

    1.7 species have already been described and named4, of those that have been already been identified only a fraction has been examined for potential medicinal, agricultural or industrial value.5 Invertebrates, which present more than 95% of the known species on earth, are animals without backbones.7 Freshwater shrimps are a species of amphipod, which is an animal order within the class crustacea. The freshwater shrimp has the binomial name Gammarus pulex. They are very active and move with quick sudden movements.

    • Word count: 5343
  15. Investigation as to whether the aspect of a wall affects the growth of lichens

    The positioning of the quadrat along the wall should follow a formula so that no intentional position can be made as this will produce biased results. In order to do this there should be regular intervals between quadrat settings and they should also be set at different heights on the wall. Method Outline A 30cm by 30 cm quadrat will be used to measure lichen distribution across the wall. A metre ruler will be used to measure the height at which the quadrats are placed and also the regular interval space between quadrat settings.

    • Word count: 4300
  16. Genetics Assignment

    Only a code composed of three bases could incorporate all 20 amino acids into the structure of protein molecules, this is known as the "base triplet hypothesis"; the triplet code is called a codon. The code is universal; the same triplet code for the same amino acids in all organisms, it is degenerate; a given amino acid may be coded for by more than one codon, and it is non-overlapping which means that each triplet is read separately. Scientists knew that DNA had to replicate itself prior to cell division so that each daughter cell would obtain all of the genetic information.

    • Word count: 4660
  17. Investigating the colour variation of Littorina littoralis and their abundance across the upper, middle and lower zones of a rocky shore

    Littorina littoralis live in association with certain fucuoid algae. These algae themselves are dependent on certain environmental conditions, for example they need moisture to avoid desiccation, and also require sunlight for photosynthesis. If it were the case that upper zone of the rocky shore spends the entire time exposed to sunlight and air, and the lower zone spends none of its time exposed to sunlight and air, it is very likely that - due to the distribution of fucuoid algae, and the threat of desiccation - most Littorina littoralis will be found in between these two extremes.

    • Word count: 4920
  18. Blackfly larvae

    By carrying out a new investigation, I should be able to evaluate the living conditions that they prefer within the river. I will measure the depth of the river in different parts of the river, as this is my main variable. I will use systematic sampling, and measure every two metres along the tape, but varying the distance from the tape, so that the depths will vary more. I will also take 30 readings from the river so that my results are reliable, and I will gain a normal distribution/correlation from my results.

    • Word count: 3198
  19. Investigating what effect varying the concentration of copper sulphate has on the enzyme Catalase when catalysing the decomposition of hydrogen peroxide into water and oxygen.

    This diagram shows the enzyme-substrate complex and how the substrate fits into the enzyme as to form the products. So now we know what an enzyme is, we now need to know how the substrate binds to the enzyme as to let the reaction happen. The substrate (the molecule that needs to be broken down) binds to the active site of the enzyme. It does this by forming temporary bonds between the 'R' group of the amino acid and the substrate.

    • Word count: 6137
  20. Gm foods and Gene therapy

    Making sure an enough amount of supply of food for this boosting population is about to be a challenge in the upcoming years; but GM foods put across an oath to meet this requirement in many ways: * Herbicide tolerance * Cold tolerance * Pest resistance * Disease resistance * Nutrition * Phytoremediation * Drought tolerance/salinity tolerance * Pharmaceuticals HOW PREVALENT ARE GM CROPS WHAT PLANTS ARE INVOLVED There are above 40 plant varieties, which have finished all of the federal needs for Commercialization, according to the FDA and the US Department of Agriculture.

    • Word count: 6413
  21. The Biology of Autistic Spectrum Disorder and the Social Implications

    Other sources were BBC news archives and BBC documentary's looking at ASD. Out of the research came some surprising facts, such as 1 in 5 children being excluded from school and out of those 1 in 5, 67% have been excluded more than once because they were suffering with ASD. Why? Because schools do not recognise the symptoms of Autism nor can they provide the support that a child with Autism requires. Another reason for this exclusion is due to the disruptiveness to other children that one child with Autism can cause because of their behaviour problems.

    • Word count: 9017
  22. Study the increasing cases of food allergies and intolerances in an attempt to establish what factors could be responsible for the rising number of sufferers.

    What is Diabetes? (1.2) One of the pancreases functions is to monitor the level of blood glucose. If blood glucose levels become too high � cells in the islets of langerhans discharge insulin. Insulin then travels around the body in the blood, but exerts an effect mainly on cells in muscles, liver and adipose tissue. This hormone acts in the body by lowering blood glucose and making the cell surface membranes more permeable to glucose. It activates transport proteins in the membranes, allowing glucose to pass into cells, as well as this insulin also activates enzymes in the cells.

    • Word count: 4480
  23. Investigating the effect of trampling on salt marsh

    The salinity decreases as more aerobic respiration occurs, the excess salt is broken down and used by the plants. The conditions also change from alkaline to more acidic as salt is removed. The area I sampled was the high marsh. I didn't feel that the effect of trampling could be explored in the embryo and building dunes because people seldom explore those areas as they are not very stable. Resources to support my work- * Advanced Biology by Michael Kent. Oxford Press 2000. Page 532-533. * SNAB coursebook. Heinemann Publication 2006. Page 26-28, 56. * Field Studies Council (FSC). http://www.theseashore.org.uk/index.html.

    • Word count: 4751
  24. patterns of growth and development

    This table shows the average height for boys and girls in inches. It goes up to 13 years however only the first 8 are important to this unit. As the child grows parts of the body alter shape and size. The proportions of the body change in result of this for example at birth the head of a baby is 1/4 of the total length of it's body, whereas by the age of 7 it's only 1/6 of the total length of the child's body. The graph below shows the average weight and height by the age in months of the child.

    • Word count: 6309
  25. Investigate how the height to width ratio of Limpets varies with distance from sea

    There are two common species of Limpet found on rocky shores in England, the Common Limpet (Patella Vulgata) being the most abundant, and the Black-Footed Limpet (Patella Dipressa)(2). The Common Limpet is the largest limpet, with shells reaching a diameter of up to 6cm and generally taller shells than the Patella Dipressa; they are also more steeply concical in shape. The muscular foot colour is can vary from a greyish green to pale yellow. This species of are shorter in height but have wider diameters than the common limpet. The Black-Footed Limpet is generally flatter than the common limpet, as it is found in more exposed locations, therefore favouring a more streamline shape.

    • Word count: 5418

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