# Explain how the base sequence of DNA acts as a store of genetic information.

> IB DP Biology Standard Level (2023 syllabus) — A1.2 Nucleic acids · Explain · 4 marks

## Mark scheme (4 marks)

1. DNA contains four different nitrogenous bases (adenine, thymine, guanine, cytosine), allowing variation in sequence.
2. The sequence of bases along a polynucleotide strand encodes instructions / specifies the sequence of amino acids in a polypeptide.
3. The large number of base pairs in a DNA molecule allows an enormous variety of different sequences, giving a very large information-carrying capacity.
4. The information is stable and heritable because complementary base pairing allows the sequence to be faithfully copied and passed to daughter cells / offspring.

## Key terms

- [base sequence](https://www.gradenine.co.uk/glossary/base-sequence)

## Related

- [Revision notes for IB DP Biology Standard Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-the-base-sequence-of-c098911e) · Published by Druglandscape Ltd.