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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

    Revision notes - origins of life on Earth, chemistry of life

    5 star(s)

    * Life may have evolved in these areas using chemical energy available from vents. Abiogenesis (Urey-Miller) * Life on earth arose from organic molecules existing on the primitive earth (amino acids - basic building blocks of life) Panspermia * Suggests either very primitive organisms or complex organic compounds travelled to earth from space. In each theory, before life could have originate/evolve complex organic compounds first had to be formed. Theories differ in how these precursors formed � shallow oceans (Urey-Miller); formation of chem.

    • Word count: 2113
  2. 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
  3. Marked by a teacher

    Explain how twin and adoption studies attempt to distinguish genetic and environmental factors underlying the onset of schizophrenia within families. Review the studies and discuss two limitations of this.

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    Monozygotic (MZ) twins have almost identical genomes, while Dizygotic (DZ) twins share only approximately half their genes. However, both usually share the same rearing environment. Thus, if environmental factors entirely explain familial clustering there should be no differences in the concordances between MZ and DZ twins. Conversely, if genetic factors are important, the concordance should be higher among MZ than DZ twins. If genetic factors alone were sufficient determinants, there should be a 100% concordance among MZ twins. In a Finnish study, the heritability of schizophrenia was 83% if first-degree relatives had been diagnosed with the disorder, the remaining 17%

    • Word count: 1708
  4. Marked by a teacher

    The Human Genome Project

    5 star(s)

    This double-helical structure of the DNA molecule was discovered Watson and Crick in 1953, for which they received the Nobel Prize for Chemistry. The bases from each side join in pairs to form the "rungs" of the ladder-specifically, adenine always pairs with thymine, and guanine always pairs with cytosine. The genetic code is specified by the order of adenines, thymines, guanines, and cytosines in the DNA ladder. A particular section of the DNA ladder usually has a unique sequence of base pairs.

    • Word count: 2268
  5. Marked by a teacher

    Too Much Information: Genetic Testing

    5 star(s)

    Some examples of these genetic conditions include Tay-Sach's disease, Bloom syndrome, Deafness, cystic fibrosis, and many other diseases (http://www.einstein.edu/e3front.dll?durki=7158). Although many of these conditions are fatal, the ones that are not can be treated early, even before symptoms develop when possible, or if not treated, at least monitored because of the person's high risk of becoming afflicted. If genetic testing is 95 per cent accurate, which is a reasonable margin of error by any standard, then one in twenty people who take the test will get a false result.

    • Word count: 938
  6. Marked by a teacher

    Compare the Similarities and Differences between Meiosis and Mitosis

    4 star(s)

    These daughter cells are clones to the parent cell. On the other hand, meiosis provides gametes that contain only half the number of chromosome number of an adult cell so that when gametes fuse together in fertilisation, a diploid zygote is formed. Genetic materials in daughter cells of meiosis are slightly different to adult cell due to variation from independent assortment and crossing-over of material. Overview of different phases: Both mitosis and meiosis consists of four main phases: prophase, metaphase, anaphase & telophase.

    • Word count: 629
  7. Marked by a teacher

    Biology Issue Report on GM Foods

    4 star(s)

    These two sets of figures do not necessarily tally but the current population is not currently receiving enough food and rising population is not the only factor in food demand. In addition to population growth and reduced rainfall, soil fertility can be depleted by a lack of access to fertiliser and bad farming practices which reduces the area suitable for crops and pasture. Genetic Modification of Crops ? A Biological Solution One solution in combatting food shortages and ensuring healthy yield is ensuring that crops are chosen for planting which are able to grow with a minimal amount of water.

    • Word count: 2177
  8. Marked by a teacher

    Research Project - Could stems cells provide a cure for diabetes?

    4 star(s)

    Some glycogen or fat is broken down into glucose and some is released back into the bloodstream to keep the sugar levels in the blood at a normal level. Insulin is made my cells called beta cells which are part of the islets - islands of cells - within the pancreas. [11] Type of diabetes: A person with diabetes has a disorder where the glucose quantity in the body is too high. This can be due to the fact the body is not producing enough insulin to help level it, or that the body cells are not responding correctly to the insulin that is produced by the pancreas.

    • Word count: 3595
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    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
  10. Marked by a teacher

    Evolution. This issue report will aim to address the Theory of Evolution by explaining key concepts and ideas in an informative and unbiased way. It will set forth to describe the theory, by highlighting its main components,

    4 star(s)

    They are convinced that they can draw definite conclusions about the origins of life. There are other rationally sound models that deny the original Theory, branding it incorrect. However, are biologists justified in stating that the Theory is ultimately flawless and cannot be refuted? They have to convince everyone that their exposition of science is valid. Before they can find a solution to their problem, let's go back to basics. Firstly, what is the definition of biological evolution? "...biological evolution is defined as descent with modification from a common ancestor."

    • Word count: 2081
  11. Marked by a teacher

    The Loss of the Lemur: The Road to Extinction

    4 star(s)

    I undertook a visit to Woburn Safari Park, which keeps this sub-species of lemur, in order to find the answers to these questions and visit the very animals facing extinction half way around the world. The Cause Although the problem of the declining lemur population was identified by 1986, the problems in Madagascar are still highly prevalent and affecting the subspecies greatly. There are two main causes for this decline, highlighted during the visit by Adele Clegg, Head of Learning at Woburn Safari Park.

    • Word count: 2074
  12. Marked by a teacher

    Five Kindom vs Three domain classification

    4 star(s)

    Each Kingdom is divided into smaller groups called phyla.Each phylum is divided into classes, each class into orders, and each order into families, each family into genera, and each genus into species. Species represent one type of an organism such as h**o sapiens (species have to be in italics or underlined). Monera Many biologists now divide Monera into the Eubacteria and Archeobacteria (Three division). Monera individuals are single celled and may or may not move. They have a cell wall however they don't have chloroplasts, organelles or a nucleus, they are usually very tiny and are green in colour.

    • Word count: 1014
  13. 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
  14. Marked by a teacher

    Understanding DNA Coursework

    4 star(s)

    The phosphate group PO4H2 negatively charged, and is linked to the pentose sugar. The pentose sugar consists of 5 carbons, the sugar present in RNA is ribose, and deoxyribose sugar is present in DNA. Deoxyribose has one less oxygen in its molecule (refer to Differences between DNA and RNA section). Lastly the nitrogen-containing base consists of 5 types in DNA and RNA. The nitrogen containing bases in DNA are Adenine, Thymine, Guanine and Cytosine (ATGC). However, RNA has the three bases AG AND C, but T is replaced by a different base, only found in RNA; uracil (U).

    • Word count: 1314
  15. 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
  16. Marked by a teacher

    Mitosis and Meiosis, the defining differences.

    4 star(s)

    The cell produces many materials essential for its own growth and for carrying out all its functions. DNA replication occurs during interphase. Mitosis: this is the process of nuclear division Cell division: this is the process of division of the cytoplasm into two daughter cells. Although these are the main stages, many sub stages exists allowing further detail into what happens during the cell cycle. Prophase is the longest stage in Mitosis. The chromosomes become visable as long threads, and start to coil up and become shorter and thicker. During Mitosis in animal cells, the centriole divides and moves to opposite poles of the nucleus.

    • Word count: 1332
  17. Marked by a teacher

    Human Cloning Assignment

    4 star(s)

    Each group of researchers has its own specific technique. The best known is the Roslin technique, and the most effective and most recently developed is the Honolulu technique. The cloning of Dolly has been the most important event in cloning history. Not only did it spark public interest in the subject, but it also proved that the cloning of adult animals could be accomplished. Previously, it was not known if an adult nucleus was still able to produce a completely new animal. Genetic damage and the simple deactivation of genes in cells were both considered possibly irreversible.

    • Word count: 2972
  18. Marked by a teacher

    Pros and Cons of Genetic Engineering

    4 star(s)

    DNA discovery is attributed to the research of three scientists, Francis Crick, Maurice Wilkins, and James Dewey Watson in 1951. They were all later accredited with the Nobel Prize in physiology and medicine in 1962. Viewpoint 1 The possibilities of genetic engineering are endless. Once the power to control the instructions, given to a single cell, are mastered anything can be accomplished. For example, insulin can be created and grown in large quantities by using an inexpensive gene manipulation method of growing a certain bacteria.

    • Word count: 1950
  19. Marked by a teacher

    natural selection and the effects of environmental change

    3 star(s)

    over many generations everyone get more like each other, to an eventual crescendo where everyone are clones of one another, this theory failed also to answer how several generations later, a trait unseen for 5 generations, suddenly turns up). This was a concept widely accepted until the importance of Mendel?s work was discovered in the early 20th century (which meant his work, although it existed, was never used in Lamarck?s theory). It also helped dispel an earlier theory Darwin had called Pangenesis.

    • Word count: 1862
  20. Marked by a teacher

    Should Gene therapy be allowed to prevent cystic fibrosis?

    3 star(s)

    The problem in doing it is integrating the DNA into the genome and the rapidly dividing nature of cells prevents gene therapy from achieving any long term cure. If patients wanted a longer and stable cure, they will have to undergo multiple rounds of gene therapy. * There are problems with viral vector; a study has shown potential problems to the patient, such as inflammatory, toxicity and immune responses. Furthermore if the viral vector starts to recover, there is always a possibility that it could cause disease.

    • Word count: 2948
  21. Marked by a teacher

    Can Germ line Gene Therapy be used as a treatment for Huntingtons Disease?

    3 star(s)

    When a mutation occurs, this protein is no longer produced and instead a different form of protein is produced. This protein initially causes very little harm to the brain, but after a prolonged time, it damages nerve cells in the brain and leads to Huntington's disease. The full process of Huntington's disease is still very unclear. Scientists continue research on patient as to how and why this happens and what protein is made from the mutation. Solution There are many solutions to combat Huntington's disease. gene therapy is the method that I will be studying in this report. Gene therapy is a complex process which takes patience and resilience to complete.

    • Word count: 2665
  22. Marked by a teacher

    Arguments For And Against The Development of A Genetic Profile For All Members of Society

    3 star(s)

    (1991)].In more recent times, DNA fingerprinting's impact on science, law and politics has been quite dramatic. One common practice in countries such as the U.S is that a genetic fingerprinting profile of a citizen who comes across any kind of "run-in" (Big or small) with the law is kept in a database. Keeping such a database of not only convicted criminals but that of people who are proven innocent has caused much controversy. (Rosen, C). DNA fingerprinting has been challenged in the past due to it validity in court cases because: o The probability of finding a match for a particular DNA pattern was found by multiplying the probability of the separate loci in a particular reference population.

    • Word count: 1226
  23. 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
  24. Marked by a teacher

    Daphnia Write-Up

    3 star(s)

    We set up the different concentrations of caffeine. 0%, 0.125%, 0.25% and 0.5%. We couldn't use tap water, only distilled water, as tap water contains chlorine which can harm the daphnia. So 0% contained no caffeine, only distilled water. 3. We took two glass slides, and put a drop of chilled water in between them: this was so that the heat of the microscopes bulb did not harm the daphnia. 4. We captured a daphnia from the main tank which contained many; we tried to select the largest one possible.

    • Word count: 775
  25. Marked by a teacher

    Thalassaemia is an inherited disease that is caused when there are mutations or a missing gene that affects how haemoglobin is produced. Haemoglobin is the protein in red blood cells that carries oxygen around the body.

    3 star(s)

    or major (b) Alpha To make enough alpha globin protein chains, you inherit two genes (one from each parent). Alpha Thalassaemia occurs when one or more of these genes are missing or have been mutated, the severity of the disease depends on how many of the genes are missing/mutated. * if one gene is affected you are likely to have no or little symptoms and are known as a silent carrier * If two genes are affected this means that you will have alpha thalassaemia trait and are therefore known as a carrier. you will also experience mild anaemia * If you have three genes affected, you will have moderate to severe anaemia, also known as haemoglobin H disease.

    • Word count: 725

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