IB Biology SL A1.2 Nucleic Acids Question Bank
Practise IB Biology SL A1.2 with questions on nucleotide structure, DNA and RNA, complementary base pairing and genetic information.
- Syllabus
- First assessment 2025
- Course
- Biology SL
- Level
- SL
Practise IB Biology SL A1.2 with questions on nucleotide structure, DNA and RNA, complementary base pairing and genetic information.
This redwood tree (Sequoia sempervirens) was blown over in 1936, but five side branches formed new roots and are now separate trees.
Three of the new trees formed from side branches of the original tree

State the molecule that trees such as redwoods use as genetic material.
DNA/deoxyribonucleic acid;
Marking guidance:
Do not accept nucleic acid or RNA
The diagram below represents a DNA nucleotide.

Identify the phosphate group and deoxyribose.
Phosphate group:
Deoxyribose:
Phosphate: I
Deoxyribose: III
[1]
Both correct for one mark.
Draw a labelled diagram to show how four nucleotides are joined together to form a double-stranded DNA molecule with two base pairs.

Two sugar-phosphate strands shown connected through bases.
A sugar-phosphate bond labelled as a covalent bond.
Hydrogen bonds labelled on line between bases.
Boxes labelled as nitrogenous bases.
Complementary base pairing/A-T/G-C.
5' - 3' linkages correctly shown; no label required.
A verified official answer image is still needed because this answer requires diagram/spatial placement.
State two differences between RNA and DNA nucleotides.
a. RNA nucleotides contain ribose and DNA nucleotides contain deoxyribose;
b. (some) RNA nucleotides contain uracil and (some) DNA nucleotides contain thymine;
Outline the bonding between DNA nucleotides.
hydrogen bonds between nucleotides of opposite strands/complementary bases/adenine and thymine and cytosine and guanine;
covalent bonds between nucleotides within strands/between sugar/deoxyribose and phosphate;