The following diagram represents a nucleotide with subunits X, Y, and Z - VCE - SSCE Biology - Question 9 - 2007 - Paper 1
Question 9
The following diagram represents a nucleotide with subunits X, Y, and Z.
This nucleotide could be identified as a monomer of DNA but not RNA if
A. X is ribose.
B. Z... show full transcript
Worked Solution & Example Answer:The following diagram represents a nucleotide with subunits X, Y, and Z - VCE - SSCE Biology - Question 9 - 2007 - Paper 1
Step 1
A. X is ribose.
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Answer
This statement is incorrect for DNA, as it contains deoxyribose instead of ribose. Therefore, if X were ribose, it would indicate an RNA nucleotide, not a DNA nucleotide.
Step 2
B. Z is thymine.
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Answer
This statement is correct. Thymine is a nitrogenous base found in DNA, but it is not present in RNA, where uracil replaces thymine. Thus, if Z is thymine, the nucleotide could be identified as a DNA monomer.
Step 3
C. Y is phosphate.
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Answer
This statement is valid as phosphates are present in both DNA and RNA. However, it does not help in determining if the nucleotide is DNA or RNA, as both contain phosphate groups.
Step 4
D. Z paired with cytosine.
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Answer
This statement is invalid for identifying a nucleotide as DNA. In DNA, thymine pairs with adenine, while cytosine pairs with guanine. If Z paired with cytosine, it would suggest a different context, particularly in relation to RNA.
