Biology · Grades 8–11
DNA structure and complementary sequences · Revision sheet
Keep bases, strands and genes distinct.
Learn the idea
DNA
DNA contains nucleotide units, each with a sugar, phosphate and base.
Pairing
In the standard double-stranded DNA model, A pairs with T and C with G.
Direction
DNA strands are antiparallel; sequence questions must say how direction is written.
Gene
A gene is a functional DNA sequence, not one whole organism or one isolated base.
Explain without looking
- A nucleotide contains which three types of components?
- Why is changing one DNA base not guaranteed to change a visible trait?
Further reading and review references
- openstax.org · reference 1
- www.genome.gov · reference 2
- www.genome.gov · reference 3
- www.genome.gov · reference 4
- www.genome.gov · reference 5
- www.genome.gov · reference 6
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Independent educational review required. Grade bands are approximate; these are not officially aligned curricula.