Bio exam questiony things

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Taz
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111242
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Bio exam questiony things
Updated:
2011-10-22 23:22:11
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SCIENCE BIOLOGY
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QUestions which are important for exams
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  1. Why is mutation the ultimate form of variation
    Mutation results in the formation of new alleles being added to a particular species. This means the base sequence of the genes is permentately changes in the DNA structure. As it results in the organism possible having entirely different variation
  2. Relationship Of DNA gennes alleles and variation
    • A DNA, which satns for deoxribose nucleic acid, is a molecule whic carries the genetic infomation in the cell and is capable of self repilcation
    • It consists of two long strands of nucleotides linked together in a double helix structure. Each of the nucleotidesare made up of a base sugar molecule and phosphate group, held together with hydrogen bonds. The comlementary base pairs, adenine and thymine, and guanine and cytosine are also linked with hydrogen bonds. The order of these DNA bases code for an indiviual and is unique for all individuals
    • A gene is a section of DNA/part of a chromosome that carries particular instruction for a particular feature to make a protein. The sequence of of the DNA bases within a gene helps determine which protein is made to display the feature or the phenotype
    • An allele is the alturning form of a gene. The difference in the base sequence of the alleles for a gene results in different protiens and therefore differnt fearutures which lead to variation
  3. Main purpose of Meiosis and Mitosis
    Mitosis involves the growth and repair by replacing old or danamges tissues whereas meiosis involves the production of 4 genetically different gametes for sexual reproduction in order to to ensure the continuation of species by keeping the number of chromosomes constant
  4. What is involoved in Meiosis and mitosis in respect to chromosomes
    In mitosis, form one parent cell you get two identical daughter cells with the exact number of chromosomes as the mother cell (diploid). Whereas in meiosis from one parent cell you get 4 gamete with half the number of chromosomes as the parent cell (haploid)
  5. How does meiosis resu;lt in gametes showing genetic variation
    • There are two very important process in meiosis that result in gamete showing genetic variation. These are crossing over and independant/random assortment
    • Crossing over- occurs when homologous chromosome pairs line up during meiosis and segements of the homologous chromosomes are swapped/exchanged resulting in chromosomes with different allele combos
    • Independant assortment- again meisis creates further varitation in a population when homologous chromosomes are randomly separted into gametes. It is random which daughter cell each of there chromosomes end up in
    • Due to this reshuffling of alleles each of the four individual gametes end up being unidentical to each other and there parent cell
  6. Exam Technique reminder SEA
    S- state, E- explain, A- apply

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