Heredity: JAMB Biology Questions, Answers & Notes

What Heredity covers in the JAMB Biology syllabus

Heredity is the passing of characteristics from parents to offspring, studied in genetics (pioneered by Gregor Mendel). Genes — the units of heredity, made of DNA — sit on chromosomes in the nucleus. Alleles are alternative forms of a gene: a dominant allele is expressed whenever present, a recessive one only when two copies occur. An organism is homozygous (two identical alleles) or heterozygous (two different). The genotype is the genetic make-up; the phenotype is the appearance. A Tt × Tt cross gives a 3:1 ratio of dominant to recessive (use a Punnett square). Human sex is set by chromosomes (XX female, XY male). Variation is differences within a species, and a mutation is a sudden change in the DNA (e.g. causing sickle-cell anaemia).

For Heredity, JAMB expects you to be able to:

• Define heredity, genetics, genes, chromosomes, DNA and alleles
• Distinguish dominant/recessive, homozygous/heterozygous, genotype/phenotype
• Solve simple monohybrid crosses and explain sex determination and variation

Key facts & revision notes: Heredity

These are the recurring points our Heredity questions test — revise them until each feels automatic, then practise the questions above to lock them in.

• Heredity is the passing of characteristics (traits) from parents to offspring.
• Genetics is the study of heredity and variation.
• A gene is the basic unit of heredity, carrying information for a characteristic.
• Genes are carried on chromosomes in the cell nucleus.
• Genes are made of DNA (deoxyribonucleic acid), which carries the genetic code.
• Gregor Mendel, through his work on pea plants, is regarded as the father of genetics.
• Alleles are alternative forms of a gene controlling a trait.
• A dominant allele is expressed whenever it is present (masking a recessive allele).
• A recessive allele is expressed only in the absence of a dominant allele (i.e.
• Homozygous means having two identical alleles for a gene.
• Heterozygous means having two different alleles for a gene.
• The genotype is the genetic make-up; the phenotype is the observable appearance.
• The phenotype is the visible expression of the genotype (e.g.
• Tt × Tt gives TT, Tt, Tt, tt → 3 showing the dominant (tall) to 1 recessive (short).
• Human females have two X chromosomes (XX); males have XY.
• Human males have one X and one Y chromosome (XY).
• Variation refers to the differences among individuals of the same species.
• A mutation is a sudden, heritable change in the genetic material (DNA).
• Sickle-cell anaemia is an inherited disorder caused by abnormal (sickle) haemoglobin.
• A Punnett square is used to predict the genotypes and ratios of offspring in a cross.
• Inherited traits make offspring resemble their parents.
• Gametes carry the genes to the next generation.
• Human body cells have 46 chromosomes (23 pairs).
• Gametes are haploid, with 23 chromosomes.

Worked examples

Three Heredity questions with the answer and a short explanation, so you can see how the topic is set before you practise the full set.

How Heredity is tested in JAMB Biology

Our Heredity bank holds 40 questions (3 easy, 17 medium, 20 hard). JAMB Biology typically returns to Heredity year after year, so steady practice on this topic is high-value revision. Questions are multiple-choice with four options, and at UTME pace you get roughly 40 seconds each — which is why timed practice matters.

How to answer Heredity questions

Work the stem first and predict the answer before you look at the options; then eliminate the ones that contradict the key facts above. Watch for “which is not…”, “all of the above” and “except” style stems, which are where rushed candidates lose easy marks on Heredity. If a calculation or a precise definition is involved, work it from first principles rather than guessing from a half-remembered rule. When two options look right, re-read the stem for the qualifier that separates them — JAMB rarely repeats an option by accident. If you are still unsure, eliminate the two weakest choices to lift your odds, flag the question, and move on; never burn a full minute on one Biology item when the exam gives you about forty seconds each. Then come back to flagged questions with whatever time remains. The single most reliable way to get faster at Heredity is repeated timed practice, so use the button above until the recurring patterns feel automatic.

Common mistakes to avoid in Heredity

The errors that cost marks on Heredity are usually careless rather than conceptual: misreading a negative stem, confusing two similar terms, or rushing a definition you actually know. Candidates also over-rely on “expo” and last-minute cramming instead of understanding the topic — which fails the moment JAMB rephrases a familiar idea. Treat every option as a claim to be checked against the facts above, keep your working tidy for any calculation, and don’t change a considered answer on a hunch. Above all, revise Heredity actively by answering questions, not just by re-reading notes — recall under time is what the exam rewards.

Frequently asked questions

Is Heredity part of the JAMB Biology syllabus?

Yes. Heredity is a recognised topic in the JAMB Biology syllabus, covering define heredity, genetics, genes, chromosomes, DNA and alleles. You should be able to recall its key facts and apply them to multiple-choice questions.

How many Heredity questions can I practise on Belmadeng?

There are 40 original, JAMB-standard Heredity questions in our free bank, each with the correct answer and a worked explanation. You can practise them untimed or as a timed test.

What are the most important points to know about Heredity?

Heredity is the passing of characteristics from parents to offspring, studied in genetics (pioneered by Gregor Mendel). Genes — the units of heredity, made of DNA — sit on chromosomes in the nucleus. Alleles are alternative forms of a gene: a dominant allele is expressed whenever present, a recessiv…

How do I answer Heredity questions quickly in JAMB?

Read the stem carefully, eliminate clearly wrong options, and match the remaining choices to the key facts for Heredity. Practising timed Heredity questions builds the speed you need for UTME's pace of about 40 seconds per question.

Are these JAMB Biology Heredity questions past questions or original?

They are original questions written to JAMB (UTME) standard and mapped to the official syllabus — not reproduced past papers. This keeps them legal to use freely while closely mirroring how the real exam tests the topic.

Where can I practise Heredity questions free without signing up?

Right here — tap “Start Heredity practice” on this page to begin instantly. Belmadeng's CBT practice is completely free and needs no sign-up, download or subscription.

About these questions: original, JAMB-standard items written from the official UTME Biology syllabus (last reviewed 2026-09-18). Belmadeng is an independent study platform and is not affiliated with JAMB. Spotted an error? Use the report link.