Replication of DNA
DNA polymerase, primers, ligase, complementary base pairing and repeated heating and cooling in PCR.
How to study Higher Biology
Move from accurate biological mechanisms to unfamiliar data, experimental evidence and justified conclusions. Use current official materials for the written, extended-response and controlled-assignment formats that this question bank does not reproduce.
Core concepts
Concept 1
Explain how primers provide a starting point and DNA polymerase adds nucleotides to the 3′ end.
Exam cue: Explain how primers provide a starting point and DNA polymerase adds nucleotides to the 3′ end.
Concept 2
Explain why fragments form on one template and how DNA ligase joins them.
Exam cue: Explain why fragments form on one template and how DNA ligase joins them.
Concept 3
Apply denaturation, primer annealing and extension to PCR amplification and its practical uses.
Exam cue: Apply denaturation, primer annealing and extension to PCR amplification and its practical uses.
Risk pitfalls and guardrails
DNA polymerase does not join fragments; ligase does.
Guardrail: Check vocabulary, sequence, direction, compartment, units and whether the evidence supports causation or only an association.
PCR copies only the region bounded by suitable complementary primers.
Guardrail: Check vocabulary, sequence, direction, compartment, units and whether the evidence supports causation or only an association.
Memory anchors
PCR cycle
Separate, settle primers, synthesise.
Polymerase direction
New DNA grows only by addition to a 3′ end.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
During DNA replication, to which end of a growing strand does DNA polymerase add a nucleotide?
Why is a primer required before DNA polymerase can copy a DNA template?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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