IGCSE Biology glossary
Base pair
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Definition
The specific pairing of nitrogenous bases in DNA held together by hydrogen bonds: adenine (A) always pairs with thymine (T), and cytosine (C) always pairs with guanine (G). This complementary base pairing ensures accurate replication of DNA.
What to include in an exam answer
Remember A-T and C-G. In exam questions that give one DNA strand, you must write the complementary sequence. Base pairing is also crucial for understanding how DNA replicates accurately.
Example in context
If one strand of DNA has the base sequence ATCGGA, write the complementary base sequence (1 mark): TAGCCT.
Related syllabus topic
Inheritance