Genetics and Inheritance 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. The actual genetic makeup of an organism (e.g. Bb) is called its:
Genotype
Phenotype
Locus
Allele
Answer: Genotype — Genotype refers to the specific combination of alleles an organism has for a gene; phenotype is the observable trait that results.
Easy
2. An individual with the genotype Bb is described as:
Heterozygous
Homozygous dominant
Homozygous recessive
Codominant
Answer: Heterozygous — When the two alleles for a gene differ (one dominant, one recessive, as in Bb), the individual is heterozygous for that gene.
Medium
3. In simple dominant-recessive inheritance, when is a recessive phenotype expressed?
Only when the individual is homozygous recessive (e.g. bb)
Whenever at least one recessive allele is present
Only in heterozygous individuals
Never, recessive alleles are never expressed
Answer: Only when the individual is homozygous recessive (e.g. bb) — A dominant allele masks a recessive allele in a heterozygote, so the recessive phenotype only appears when both alleles present are recessive.
