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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

    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.

    5 star(s)

    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
  2. 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 Homo 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
  3. 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
  4. 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
  5. 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
  6. 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
  7. 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
  8. Marked by a teacher

    Thalassemia is a genetic (inherited) conditions affecting the blood. There are different types of thalassemia.

    3 star(s)

    Thus, the blood is in the 'surplus' mode, which can lead to symptoms and complications. (Nassar, Rechdan, 2006) Depending on the type of thalassemia, the number of abnormal hemoglobin is different. This can be a big part of the body of hemoglobin, and only a small percentage. This is basically what determines how serious to have thalassemia. There are also other individual factors. Thus, two people with the same type of thalassemia may have different severity of the disease from one state. (Nassar, Rechdan, 2006) Beta-thalassemia major Anyone with beta-thalassemia major, two genes of beta-thalassemia. Most of their hemoglobin is abnormal and does not work. This leads to severe anemia, beginning around age 4-6 months.

    • Word count: 1660
  9. Marked by a teacher

    Can The Use Of Stem Cells Be Justified?

    3 star(s)

    Labnotes - stem cells: potent research January 2003 This is a strong view taken by many religious people because of their belief that all life is sacred and life starts at the moment of fertilisation, so a fertilised cell should have the same status as a human being. Others argue that an early embryo is just a ball of cells, so it cannot have any rights. Edexcel 360 science 2006 Is it right to allow suffering to continue when it might be alleviated? At the end of 1998, two groups of scientists developed a technique for culturing embryonic stem cells.

    • Word count: 1053
  10. Marked by a teacher

    'Discuss the advantages and disadvantages of the use of gene technology.'

    With this information, parents have the choice of keeping the baby or not, to spare it from a seriously impaired or shortened life. An exciting and likely prospect in medicine is gene therapy, which is being tested currently. This would allow doctors to cure a disorder which was a result of a defective gene, and the first successful attempt was made where the gene encoding the enzyme adenosine deaminase was transferred into the bone marrow of two girls suffering from a rare blood disorder caused by the lack of this enzyme.

    • Word count: 1699
  11. Peer reviewed

    Discuss the Impact of Genome Sequences on the Study of Development

    5 star(s)

    Despite it's hazy and undramatic origins the field aquired a recognisble unity by the 1930's. One proposed question was "how do the organisms' genes produce their effect in development?" This lead to the field of developmental genetics, using the genes of an organism to explain it's development. During that period Lillie (1927) Spemann (1938) and Just (1939) said there would be no genetic theory of development until: 1. Genetisists could explain how chromosomes produce different and changing types of cell cytoplasms. 2. Genetisists could explain how genes control the earley stages of development. 3. And explain how complex phenomena, such as the sex determination mechanisms occur.

    • Word count: 1908
  12. Peer reviewed

    Brewing. During beer production the sugar in the wort is fermented by the yeast into alcohol. For this purpose yeast fungi of the species Saccharomyces cerevisiae are used.

    4 star(s)

    Yeast is able to utilise these sugars both in the presence of oxygen and when oxygen is excluded. The aerobic breakdown, which produces more energy is called respiration and the anaerobic breakdown, which produces less energy is called fermentation. Of the carbohydrates only sugars are respired or fermented by yeast. An important parameter for distinguishing individual yeast species is their ability to respire or ferment various sugars. Whether a sugar is used aerobically or anaerobically depends principally on the oxygen availability. In the presence of oxygen, yeasts obtain their energy by respiration. When the oxygen is removed metabolism changes to fermentation.

    • Word count: 1451
  13. Peer reviewed

    For each of the animal groups you have chosen, describe the structures involved in the biological process you have named. In each case, describe how these structures function, and explain how they allow each group to survive in their habitat.

    4 star(s)

    This allows the insect to have a high metabolic rate - so they can fly. Insects can also open and close their spiracles which allow them to control water loss and allows insect to live in extremely arid conditions Fish: Fish live in an aquatic environment. As water contains less oxygen than air they have developed a very efficient gas exchange system. Gas exchange takes place at the gills which are specialised structures. They have several adaptations to increase the rate of gas exchange. Gills are thin and covered in lamellae this gives the gills a very large surface area.

    • Word count: 1456
  14. Peer reviewed

    The arguments for and against developing a “genetic fingerprint” profile for all members of society

    4 star(s)

    The enzyme makes two incisions, one through each of the sugar-phosphate backbones (i.e., each strand) of the double helix without damaging the nitrogenous bases (http://en.wikipedia.org/wiki/Restriction_endonuclease, 02/03/2008). Now the DNA sections can be separated by the process of electrophoresis, which is a technique, used in the laboratories that result in the separation of charged molecules (http://www.life.uiuc.edu/molbio/geldigest/electro.html, 02/03/2008). Because DNA is a negatively charged molecule, it is able to move through a matrix of agar when an electric current is passed through.

    • Word count: 1240
  15. This essay will outline the principal features of the musculoskeletal system and look into a rare and debilitating disorder: fibrodysplasia ossificans progressiva (FOP). The devastating effects of this condition will be explored as will treatment options

    bone is typically found where strength and durability is needed, like the shaft (diaphysis) of long bones, spongy (trabecular) bone is commonly found around impact points such as the epiphyses of long bones, dispersing energy and reducing stress levels within joints. Joints (where two or more bones meet) can be classified according to their movability: fixed, semi-movable, and synovial; with synovial joints being subcategorised according to their range of motion; such as the freely movable ball-and-socket joint of the hip (Smith, 2010). Ligaments give stability to joints, holding the bones together and preventing over extension, while a cartilaginous layer on the periosteum, protects and 'cushions' the bone, combined with the viscous synovial fluid inside the joint capsule, reduces friction creating smooth motion (Glenn, 2005).

    • Word count: 1113
  16. Mean temperatures are rising in many parts of the world. The resulting temperatures may result in physiological and ecological effects on living organisms. Describe and explain these effects.

    Therefore whilst an increase in bodily temperature (a result of increase in environmental temperature) increases the kinetic energy of molecules and thereby the rate of collisions between enzyme active sites and substrate molecules, once the optimum temperature threshold has been breached, an enzyme is no longer capable of functioning as efficiently. This could lead to denaturation (though unlikely without a significant increase in mean environmental temperature), whereby molecular bonds within the enzymes structure are now broken thereby disrupting the tertiary/ quaternary structure of the polypeptide, making it useless in the catalysis of biochemical reactions.

    • Word count: 1311
  17. Human Genome Project. The work on interpretation of genome data is still in its initial stages. It is anticipated that detailed knowledge of the human genome will provide new avenues for advances in medicine and biotechnology as scienctist can identify ge

    However, the complete nucleotide sequence is only the first step in the exploration of the mystery of the genome. It will take many more years to analyse the date. Benefits The work on interpretation of genome data is still in its initial stages. It is anticipated that detailed knowledge of the human genome will provide new avenues for advances in medicine and biotechnology as scienctist canidentify genes responsible for many genetic diseases, including myotonic dystrophy, inherited colon cancer, Alzheimer's disease, etc. Biotechnology A number of companies, such as Myriad Genetics started offering easy ways to administer genetic tests, also called DNA-based tests, that can show predisposition to a variety of illnesses, including breast cancer, disorders of hemostasis, cystic fibrosis, liver diseases and many others.

    • Word count: 1710
  18. Legionnaires disease.

    Patients whom are infected with Pontiac fever usually recover within 5days without having to visit the hospital(Sherwood L. Gorbach et al.,2004). Contracting Legionnaires disease. Legionnaires' disease can be contracted by inhaling airborne water droplets containing legionellae bacterium. When mechanical action breaks the surface of the water, small water droplets are formed, which evaporate very quickly. If these droplets contain bacteria, the bacteria cells remain suspended in the air, invisible to the naked eye but small enough to be inhaled into the lungs before the water enters the stomach (Tateda et al., 2001b).

    • Word count: 1051
  19. Evolution - Darwin and the Christian view. Before Darwins discovery many believed and still belive that all creation was created by God almighty as the first book of Genesis 1:1 explains.

    Many people also believed that there is life after death; still Darwin's theory is unable to explain this statement. Evidence Darwin used to support the theory Darwin spent many years with his project, investigating the theory of evolution although he was not one hundred percent certain that all the information that he had was enough to prove his theory and he was worried that an organism might be discovered that can only be proven to be made by a creator.

    • Word count: 1752
  20. The Theory of Evolution

    As they dispersed to different islands, new populations would be formed. Every time these satellite populations dispersed, there would be greater differences between the individual species. Natural selection works as follows: 1. Variations exist in any population. 2. In and generation there are individuals that do not reach maturity and reproduce. Their characteristics are removed (passed on) 3. The organisms that survive to reproduce are best adapted to that environment as they have the variations that allowed them to survive (Survival of the fittest) 4. These favourable variations are passed onto the next generation, which become more and more common.

    • Word count: 1223
  21. DNA Database Advantage Or Disadvantage

    So if wasn't done many sickening crimes would have gone unsolved and many dangerous criminals would have remained at large Moral Issues associated with the development and subsequent issues of the National DNA database The database was created in 1995 as a crime fighting tool in 2004 a law was passed in allowing the DNA of innocent people to be retained by the police and now anyone whose arrested and not convicted has their genetic code entered into the

    • Word count: 1444
  22. Lemna Proposal

    We are going to use 20% pond water and are going to observe the competition between the lemna and algae using only the nutrients in the pond water. Lemna and algae compete for the nutrients in the pond water, which are limited due to the two plants being in the same cup. Hypothesis: When the brownish food coloring is added to the algae and the lemna in pond water, the algae will not be able to absorb blue light and will not be able to photosynthesize leading to its stunt in growth, thus immensely decreasing the competition between the algae and lemna.

    • Word count: 1137
  23. To analyse the quality and components of the two different water samples

    no. Average of sample 'a' Average of sample 'b' Average of sample 'a' and 'b' 1 3.4 6.6 5.0 GRAPH:2 showing phosphate content in sample 'A' and 'B' in 3 trials. CHLORIDE: Table: 5 to find the chloride content in the sample 'A' and sample 'B'. Trial number Sample 'A' (no. of CD3 drops added) Sample 'B' (no. of CD4 drops added) 1 20 25 2 17 22 3 19 27 Table: 6 to find the average number of CD3 and CD4 drops added in the solution.

    • Word count: 1494
  24. Chlortastic

    • Word count: 1200

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