Answer: thymine.
- A thymine
- B guanine
- C cytosine
- D uracil
Correct answer: A. thymine
Explanation: Adenine pairs with thymine (A–T) in DNA.
Helicase unwinds the double helix at the replication fork; one new strand (leading) is synthesised continuously toward the fork, while the other (lagging) must be made in short, separate Okazaki fragments because DNA polymerase only adds nucleotides 5'→3'.
Concept context
DNA structure, replication, transcription, translation, the genetic code, and gene regulation (lac operon). The single most important chapter for NEET molecular biology.