10 free IGCSE Biology Inheritance & Variation questions written in the style of Cambridge Biology papers: 3 multiple-choice and 7 structured, each with its answer and mark scheme. 4 of them are A* challenge questions, built to catch the mistakes strong students still make.
This topic covers Chromosomes, genes & proteins, Mitosis & meiosis, Monohybrid inheritance, Variation, Adaptive features, Selection. Work through the questions below, then generate a full Inheritance & Variation paper with a fresh set every time.
Generate a full Inheritance & Variation paper →The ABO blood group is controlled by three alleles. IA and IB are codominant and both are dominant to Io.
Parents have genotypes IAIB × IoIo.
What is the probability that a child has blood group O?
Answer: A
In a molecule of DNA, 32% of the bases are adenine (A).
What percentage of the bases are guanine (G)?
Answer: A
What does "survival of the fittest" mean?
Answer: D
Genes are found on chromosomes in the nucleus.
Define a gene.
Define an allele.
Describe how the sequence of bases in a gene controls the protein made.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | length of DNA coding for a protein a length of DNA that codes for a protein B1 | 1 |
| (b) | alternative form of a gene an alternative form of a gene B1 | 1 |
| (c) | triplets code amino acids; mRNA; ribosome the base sequence determines the amino acid sequence B1 mRNA copies the gene and goes to a ribosome B1 amino acids are joined in that order B1 | 3 |
Natural selection leads to evolution.
Describe the process of natural selection.
Distinguish between natural and artificial selection.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | variation; competition; survival of best adapted; reproduce; pass on alleles there is variation in a population B1 competition for resources B1 individuals better adapted survive and reproduce B1 they pass on their alleles to the next generation B1 | 4 |
| (b) | environment vs humans choose natural: environment selects B1 artificial: humans choose individuals with desired features to breed B1 | 2 |
Farmers use selective breeding to improve their crops.
Describe how a farmer could breed wheat with a higher yield.
Give one disadvantage of selective breeding.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | select best, cross, repeat many generations select plants with the highest yield B1 cross them B1 repeat over many generations B1 | 3 |
| (b) | reduced variation reduces genetic variation, making crops vulnerable to disease B1 | 1 |
Cancer can occur when mitosis is uncontrolled.
Explain how a tumour forms.
State one place where meiosis takes place in humans.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | uncontrolled cell division cells divide by mitosis in an uncontrolled way B1 forming a mass of cells (tumour) B1 | 2 |
| (b) | testes / ovaries testes or ovaries B1 | 1 |
This question is about DNA and protein synthesis.
Describe the structure of a DNA molecule.
Write the sequence of bases on the strand complementary to ATGCCA.
State how the sequence of bases in a gene determines the protein made.
Describe how a protein is made at a ribosome, starting from the gene in the nucleus.
A mutation changes one base in a gene. Explain how this could affect the protein.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | two strands; double helix; bases pair A–T, C–G two strands coiled into a double helix B1 each strand has a sequence of bases B1 bases pair A with T and C with G (complementary) B1 | 3 |
| (b) | TACGGT TACGGT B1 | 1 |
| (c) | base sequence codes for sequence of amino acids the sequence of bases determines the sequence of amino acids B1 which determines the shape and function of the protein B1 | 2 |
| (d) | mRNA copy of gene made in nucleus; moves to ribosome; ribosome reads bases; amino acids joined in correct order the gene is copied into mRNA in the nucleus B1 mRNA passes out of the nucleus to a ribosome B1 the ribosome reads the base sequence (in triplets) B1 amino acids are brought and joined in the order coded B1 | 4 |
| (e) | different amino acid; protein shape changes, may not function may code for a different amino acid B1 changing the shape of the protein so it may not function (e.g. active site) B1 | 2 |
A karyotype shows the chromosomes of a cell.
State the number of pairs of chromosomes in a human body cell.
Explain the meaning of diploid.
State the sex chromosomes of a human male.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 23 23 pairs B1 | 1 |
| (b) | two sets of chromosomes a nucleus containing two sets of chromosomes (pairs) B1 | 1 |
| (c) | XY XY B1 | 1 |
This question is about inheritance of purple and white flowers. The allele for purple (P) is dominant to the allele for white (p).
Define the terms allele and homozygous.
Two heterozygous purple parents are crossed. Draw a genetic diagram to show the genotypes and phenotypes of the offspring, and state the expected ratio.
The cross produced 400 offspring. Calculate the expected number of white offspring.
Describe how a test cross could be used to find out whether a purple individual is homozygous or heterozygous.
Explain why the observed ratio of offspring is often different from the expected ratio.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | allele: alternative form of a gene; homozygous: two identical alleles allele: an alternative form of a gene B1 homozygous: having two identical alleles of a gene B1 | 2 |
| (b) | Pp × Pp; PP, 2 Pp, pp; 3 purple : 1 white parental genotypes Pp × Pp B1 gametes P and p from each B1 offspring genotypes PP, Pp, Pp, pp B1 phenotypic ratio 3 purple : 1 white B1 | 4 |
| (c) | 100 400 × ¼ = 100 B1 | 1 |
| (d) | cross with homozygous recessive white; all purple → homozygous; some white → heterozygous cross with a homozygous recessive (pp, white) individual B1 if all offspring are purple the parent is homozygous B1 if about half are white it is heterozygous B1 | 3 |
| (e) | fertilisation is random; small sample fertilisation is random / probabilities are only close with large numbers of offspring B1 | 1 |
In the 0610 syllabus, Inheritance & Variation covers Chromosomes, genes & proteins, Mitosis & meiosis, Monohybrid inheritance, Variation, Adaptive features, Selection.
This page has 10 Inheritance & Variation questions with answers. For more, the free generator on mentorriyaz.in builds a new Inheritance & Variation paper with a full mark scheme each time you click.
Riyaz Shaikh has mentored IGCSE, IB and A Level students for 15+ years, one-on-one, online and in Mumbai. The hardest questions on this site are the ones he uses to find a student's weak points.
Meet Riyaz →Original Cambridge-style practice questions written for mentorriyaz.in. These are not Cambridge past paper questions, and this site is not affiliated with or endorsed by Cambridge University Press & Assessment. Updated 2026-11-04. Paper generator · mentorriyaz.in