The DNA analysis of a fruit fly shows that 22% of nitrogenous bases are thymine.The percentage of guanine bases in this DNA would be
Correct answer: B. 28%
- A. 22%
- B. 28%
- C. 44%
- D. 56%
Explanation
In DNA, the amount of adenine (A) equals the amount of thymine (T), and the amount of guanine (G) equals the amount of cytosine (C). If thymine is 22%, then adenine is also 22%. This accounts for 44% of the DNA. The remaining 56% must be split equally between guanine and cytosine, making guanine 28%. Option B is correct because it aligns with these base pairing rules. The other options do not follow the rule that the sum of adenine and thymine, and guanine and cytosine, must each equal 100%.
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About Structure of DNA
DNA structure includes nucleotides made of deoxyribose, phosphate and nitrogenous bases, arranged in two antiparallel polynucleotide strands. Questions cover the double helix, phosphodiester and hydrogen bonds, complementary base pairing between adenine and thymine and between guanine and cytosine, and the significance of major and minor grooves.
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