DNA vs DNase: Structure and Function — NEET Biology
📚 Practice ConceptCan you think of any difference between DNAs and DNase?
Which of the above statements regarding the components and pairing rules of nucleic acids are correct? S1: In DNA, the complementary base to cytosine is guanine, forming three hydrogen bonds. S2: The sugar in DNA is ribose, which contains an additional -OH group at the 2' position compared to deoxyribose. S3: Uracil is a pyrimidine base found exclusively in RNA, replacing thymine. S4: Adenine and Guanine are purines present in both DNA and RNA. S5: The stability difference between DNA and RNA is partly attributed to RNA being less reactive due to the absence of a 2'-OH group.
View solution & NCERT explanation
Correct answer: B — S1, S3, S4
This question assesses knowledge of base pairing rules, chemical composition of DNA and RNA, and reasons for their differential stability. S1 is correct: As stated in NCERT, 'Guanine is bonded with Cytosine with three H-bonds.' This confirms the complementary pairing. S2 is incorrect: The NCERT clearly states, 'a pentose sugar (ribose in case of RNA, and deoxyribose for DNA)'. It also mentions, 'In RNA, every nucleotide residue has an additional –OH group present at 2'-position in the ribose.' Therefore, deoxyribose lacks this -OH group, making this statement incorrect. S3 is correct: The NCERT specifies, 'Uracil is present in RNA at the place of Thymine.' Uracil is indeed a pyrimidine base. S4 is correct: The NCERT lists 'Purines (Adenine and Guanine)' as types of nitrogenous bases, which are common to both DNA and RNA. S5 is incorrect: The NCERT states, 'Further, 2'-OH group present at every nucleotide in RNA is a reactive group and makes RNA labile and easily degradable. ... Therefore, DNA chemically is less reactive and structurally more stable when compared to RNA.' RNA is more reactive and less stable due to the presence of the 2'-OH group, not its absence. Therefore, statements S1, S3, and S4 are correct.
What does NCERT say about Can you think any?
Has this concept appeared in NEET?
Which chapter is this from?
Through deep analysis of NEET and NTA, 176 of the 180 ReNEET 2026 (June 21) questions were already in the MedicNEET question bank before the exam.
176/180MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.