DNA: Code of Life is one of 10 topics in the Grade 12 Life Sciences CAPS syllabus, covered across 3 lessons on Study Vault. Below are real practice questions from this topic with full worked answers.
Sample practice questions
Easy
1. DNA is best described as a:
Double helix of two antiparallel nucleotide strands
Single strand of amino acids
Circular protein molecule
Triple helix of three nucleotide strands
Answer: Double helix of two antiparallel nucleotide strands — DNA consists of two nucleotide strands wound around each other in a double helix, running in opposite (antiparallel) directions.
Easy
2. Which base always pairs with adenine in DNA?
Thymine
Guanine
Cytosine
Uracil
Answer: Thymine — Complementary base pairing in DNA is A-T and G-C; adenine always pairs with thymine via two hydrogen bonds.
Easy
3. A nucleotide is made up of which three components?
A deoxyribose sugar, a phosphate group, and a nitrogenous base
A protein, a lipid, and a sugar
Two nitrogenous bases and a phosphate group
A ribosome, an amino acid, and a sugar
Answer: A deoxyribose sugar, a phosphate group, and a nitrogenous base — Each DNA nucleotide has three parts: a deoxyribose sugar, a phosphate group, and one of the four nitrogenous bases (A, T, G or C).
