Excretion: JAMB Biology Questions, Answers & Notes

What Excretion covers in the JAMB Biology syllabus

Excretion removes the toxic waste products of metabolism (urea, carbon dioxide, excess water/salts) — different from egestion, which removes undigested food. In mammals, the excretory organs are the kidneys (remove urea as urine via nephrons that filter in the glomerulus and reabsorb useful substances), the lungs (carbon dioxide and water vapour), the skin (sweat) and the liver (makes urea from excess amino acids). Urine flows kidney → ureter → bladder → urethra. Plants excrete oxygen and water vapour through stomata and store some wastes in leaves and bark. Nitrogenous waste is ammonia in fish, urea in mammals, and uric acid in birds/insects (saving water).

For Excretion, JAMB expects you to be able to:

• Define excretion and distinguish it from egestion
• State the excretory organs and products in mammals and plants
• Describe the kidney's role and nitrogenous wastes in different animals

Key facts & revision notes: Excretion

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

• Excretion removes the waste products of metabolism (e.g.
• The kidneys are the main excretory organs, removing urea and excess water and salts as urine.
• Mammals mainly excrete urea (formed in the liver from excess amino acids).
• The nephron is the microscopic functional (filtering) unit of the kidney.
• The skin excretes water, salts and some urea through sweat.
• The lungs excrete carbon dioxide and water vapour produced during respiration.
• The liver deaminates excess amino acids, forming urea, which the kidneys excrete.
• The ureter carries urine from the kidney to the bladder; the urethra carries it out of the body.
• The large intestine egests undigested food (egestion), which is not excretion of metabolic waste.
• Egestion (defecation) removes undigested food; it is not excretion of metabolic waste.
• Plants release oxygen (and water vapour) through the stomata.
• Plants store some waste (e.g.
• tannins) in leaves and shed them, and in bark and dead tissues.
• Useful substances (glucose, some water and salts) are reabsorbed along the kidney tubule.
• The urinary bladder temporarily stores urine before it is released.
• Sweating removes waste and also cools the body as the sweat evaporates.
• Excess water is removed, so the urine is dilute and greater in volume.
• Blood is filtered under pressure in the glomerulus within the Bowman's capsule.
• Metabolic wastes are toxic if they accumulate, so they must be excreted.
• Aquatic animals like fish excrete ammonia, which is quickly diluted and carried away by water.
• Birds and insects excrete uric acid (a semi-solid paste), which conserves water.
• The skin excretes waste in sweat.
• Excess amino acids are converted to urea in the liver.
• The urethra carries urine out of the body.

Worked examples

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

How Excretion is tested in JAMB Biology

Our Excretion bank holds 40 questions (5 easy, 15 medium, 20 hard). JAMB Biology typically returns to Excretion 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 Excretion 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 Excretion. 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 Excretion is repeated timed practice, so use the button above until the recurring patterns feel automatic.

Common mistakes to avoid in Excretion

The errors that cost marks on Excretion 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 Excretion actively by answering questions, not just by re-reading notes — recall under time is what the exam rewards.

Frequently asked questions

Is Excretion part of the JAMB Biology syllabus?

Yes. Excretion is a recognised topic in the JAMB Biology syllabus, covering define excretion and distinguish it from egestion. You should be able to recall its key facts and apply them to multiple-choice questions.

How many Excretion questions can I practise on Belmadeng?

There are 40 original, JAMB-standard Excretion 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 Excretion?

Excretion removes the toxic waste products of metabolism (urea, carbon dioxide, excess water/salts) — different from egestion, which removes undigested food. In mammals, the excretory organs are the kidneys (remove urea as urine via nephrons that filter in the glomerulus and reabsorb useful substanc…

How do I answer Excretion questions quickly in JAMB?

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

Are these JAMB Biology Excretion 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 Excretion questions free without signing up?

Right here — tap “Start Excretion 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.