QPaperGen

(i)
Given:
Total nucleotides = 5375
Composition:
A = 33%, G = 18%, C = 33%, T = 17%
According to Chargaff’s rule:
A=TandG=CA = T \quad \text{and} \quad G = CA=TandG=C
Here:
A ≠ T (33% ≠ 17%)
G ≠ C (18% ≠ 33%)

✅ Conclusion:
The given DNA sample does not obey Chargaff’s rule, therefore it is not double-stranded DNA.
It is most likely single-stranded DNA or RNA (where A–T and G–C pairing is not necessarily equal).

(ii)
Given (for one strand):
A = 26%, T = 23%, C = 24%, G = 27%
In the complementary strand,


A pairs with T


T pairs with A


C pairs with G


G pairs with C


So the complementary strand will have:


A = 23% (because the original strand has 23% T)


T = 26% (because the original strand has 26% A)


C = 27% (because the original strand has 27% G)


G = 24% (because the original strand has 24% C)

✅ Complementary strand composition:
A = 23%, T = 26%, C = 27%, G = 24%

(iii)
Given: Cytosine = 26%
By Chargaff’s rule for double-stranded DNA:
C=G⇒G=26%C = G \Rightarrow G = 26\%C=G⇒G=26%
Now total of C + G = 52%
Remaining (A + T) = 100 − 52 = 48%
Since A = T,
A=T=482=24%A = T = \frac{48}{2} = 24\%A=T=248​=24%
✅ Therefore:
Thymine = 24%

✅ Final Answers:
PartQuestionAnswer / Conclusion(i)Given base ratios 33%, 18%, 33%, 17%Does not follow Chargaff’s rule → likely single-stranded DNA(ii)Complementary strand compositionA = 23%, T = 26%, C = 27%, G = 24%(iii)If C = 26%Then T = 24%