eZine · Nigerian exams
Excretion
JAMB Biology topic guide with 2 practice questions.
What to revise
- types of excretory structures: contractile vacuole, flame cell, nephridium, Malpighian tubule, kidney, stoma and lenticel
- excretory mechanisms: kidneys, lungs, skin
- excretory products of plants
You should be able to
- define and state the significance of excretion
- relate the characteristics of each excretory structure to its functions
- relate the structure of the kidneys to their excretory and osmoregulatory functions
- identify the functions and excretory products of the lungs and the skin
- deduce the economic importance of excretory products of plants (e.g. carbon (IV) oxide, oxygen, tannins, resins, gums, mucilage, alkaloids)
From JAMB's Biology syllabus official. Full syllabus →
eZine's published bank has 9 questions on this topic (counted 29 October 2026).
Practice questions
Question 1 · Excretion
A contractile vacuole is common in freshwater Amoeba but usually absent in marine Amoeba. This is best explained by the fact that
Show answer and explanation
Answer: D. water constantly enters freshwater Amoeba by osmosis and must be pumped out
Pond water is hypotonic to the cytoplasm, so water flows in and the vacuole pumps it out; sea water is roughly isotonic, so little water enters. Marine Amoeba still make waste (lost by diffusion); they do not have flame cells; freshwater Amoeba gain rather than lose water.
eZine practice question (original, teacher-reviewed)
Question 2 · Excretion
Which sequence traces the path of a urea molecule from blood to the outside of the body?
Show answer and explanation
Answer: A. glomerulus → Bowman's capsule → tubules → collecting duct → ureter → bladder → urethra
Urea is filtered from the glomerulus into the capsule, passes along the tubules to the collecting duct, then the ureter carries urine to the bladder and out through the urethra. The other sequences reverse the capsule/glomerulus, ureter/urethra order or start from the renal vein, which carries filtered blood away.
eZine practice question (original, teacher-reviewed)
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