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Cards In This Set
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State three ways in which genetic variation can be increased in sexually reproducing organisms
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Mutation, meiosis and fusion of gametes
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How is genetic information increased in asexually reproducing organisms?
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Mutation only
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Give two reasons why a sample may not be representative of the population as a whole
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Samplng bias, chance variation
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How may sampling bias be prevented?
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By using ranom sampling -effectively using a computer to generate sampling sites
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What is intraspecific variation?
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Variation within a species.
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What are the three basic components of a nucleotide?
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Deoxyribose (sugar) phosphate group, organic base
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In terms of the structure of the DNA molecule, explain why the base pairings are not adenin with guanine and themine with cytosine?
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Adenine and guanine are longer molecules than thymine and cytosine. The distance between the two phosphate/deoxyribose 'uprights' is constant in the DNA molecule. Pairing ademine and guanine would produce a long 'rung' while pairing thymine and cytosine produces a short 'rung'.
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Suggest a reason why the base pairings of adenine with cytosine and guanine with thymine do not occur
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The bases are linked by hydrogen bonds. The molecular structures could be such that hydrogen bonds do no form between adenine and cytosine and between guanine and thymine.
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If the bases on one strand of DNA are TGGAGACT what is the base sequence for the other strand?
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ACCTCTGA
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If 19.9% of the base pairs in human DNA are auanine what percentage if human DNA is thymine? Show your reasoning.
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30.1%. If 19.9% is guanine then, as guanine always pairs with cytosine, it also makes up 19.9% of the bases in the DNA. So together they make up 39.8%. This means the remaining 60.2% of DNA must be adenine and thymine in equal amounts. So half of this 30.1%
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