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Excretory Products and Their Elimination — NEET Biology MCQs with Solutions
Free NEET Biology Excretory Products and Their Elimination MCQs with step-by-step solutions covering Modes of Excretion, Human Excretory System & Nephron, Urine Formation, Concentration of Filtrate (Counter-current), Regulation & Osmoregulation, Disorders & Other Excretory Organs. Practise online on Prepizo — no login needed.
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Sample questions with solutions
Q1 — Modes of Excretion · easy · theory
Animals that excrete nitrogenous waste mainly as ammonia are called:
A. Uricotelic
B. Guanotelic
C. Ureotelic
D. Ammonotelic ✓ Correct
Solution: Ammonotelic animals (most aquatic animals) excrete ammonia, which is highly soluble and toxic but easily diluted.
Q2 — Modes of Excretion · easy · theory
Mammals, including humans, are ______ because they mainly excrete:
A. Ureotelic; urea ✓ Correct
B. Uricotelic; urea
C. Uricotelic; uric acid
D. Ammonotelic; ammonia
Solution: Mammals convert toxic ammonia to less toxic urea (ureotelism), excreted by the kidneys.
Q3 — Human Excretory System & Nephron · easy · theory
The functional (structural) unit of the kidney is the:
A. Nephron ✓ Correct
B. Neuron
C. Alveolus
D. Glomerulus only
Solution: Each kidney has about a million nephrons — the units that form urine.
Q4 — Human Excretory System & Nephron · easy · theory
The tuft of capillaries where blood filtration begins in the nephron is the:
A. Glomerulus ✓ Correct
B. Ureter
C. Loop of Henle
D. Collecting duct
Solution: The glomerulus (enclosed by Bowman's capsule) is the site of ultrafiltration of blood.
Q5 — Urine Formation · easy · theory
The three basic processes involved in urine formation are:
A. Ingestion, digestion and egestion
B. Diffusion, osmosis and active transport
C. Glomerular filtration, reabsorption and secretion ✓ Correct
D. Filtration, digestion and absorption
Solution: Urine formation = glomerular filtration → tubular reabsorption → tubular secretion.
Q6 — Urine Formation · easy · theory
The filtration of blood at the glomerulus is called ______ because it filters everything except large proteins and cells:
A. Osmosis
B. Ultrafiltration ✓ Correct
C. Reabsorption
D. Secretion
Solution: Ultrafiltration under blood pressure passes water and small solutes into Bowman's capsule, retaining proteins/cells.
Q7 — Regulation & Osmoregulation · easy · theory
The hormone that promotes water reabsorption in the kidney (reducing urine volume) is:
A. Adrenaline
B. Thyroxine
C. Insulin
D. ADH (vasopressin) ✓ Correct
Solution: ADH (anti-diuretic hormone) increases water reabsorption from the DCT/collecting duct, concentrating urine.
Q8 — Regulation & Osmoregulation · easy · theory
When the body is dehydrated, ADH secretion ______ and urine becomes ______:
A. Stops; watery
B. Increases; more concentrated (less volume) ✓ Correct
C. Decreases; more dilute
D. Increases; more dilute
Solution: Dehydration → more ADH → more water reabsorbed → concentrated, low-volume urine.
Q9 — Disorders & Other Excretory Organs · easy · theory
The artificial process used to remove nitrogenous wastes from the blood of kidney-failure patients is:
A. Filtration by liver
B. Transfusion
C. Transpiration
D. Haemodialysis ✓ Correct
Solution: Haemodialysis uses an artificial kidney to filter urea/wastes from the blood when kidneys fail.
Q10 — Disorders & Other Excretory Organs · easy · theory
The accumulation of urea in the blood due to kidney malfunction is called:
A. Anaemia
B. Glycosuria
C. Uremia ✓ Correct
D. Diabetes
Solution: Uremia is a high blood urea level from kidney failure; it can be treated by dialysis.
Q11 — Modes of Excretion · easy · numerical
Malpighian tubules are the principal excretory organs of:
A. Insects such as the cockroach ✓ Correct
B. Prawns and other crustaceans
C. Planaria and other flatworms
D. Earthworms and other annelids
Solution: Malpighian tubules remove nitrogenous wastes (mainly uric acid) in insects; annelids use nephridia, flatworms use protonephridia and crustaceans use antennal (green) glands.
Q12 — Modes of Excretion · easy · numerical
Flame cells (protonephridia) are the excretory structures found in:
A. The cockroach
B. The earthworm
C. The prawn
D. Planaria (flatworms) ✓ Correct
Solution: Protonephridia with flame cells carry out excretion and osmoregulation in flatworms like Planaria, rotifers and some annelid larvae.
Q13 — Modes of Excretion · easy · numerical
Antennal glands, also called green glands, are the excretory organs of:
A. Insects such as the honeybee
B. Molluscs such as Pila
C. Flatworms such as Planaria
D. Crustaceans such as the prawn ✓ Correct
Solution: Antennal (green) glands open at the base of the antennae and perform excretion in crustaceans like prawns and crayfish.
Q14 — Modes of Excretion · easy · numerical
The uricotelic mode of excretion, which conserves the most water, is shared by:
A. Bony fishes, tadpoles and prawns
B. Earthworms, leeches and Planaria
C. Reptiles, birds and insects ✓ Correct
D. Mammals, sharks and adult frogs
Solution: Reptiles, birds, land snails and insects excrete nitrogen as insoluble uric acid (paste/pellets), losing very little water.
Q15 — Human Excretory System & Nephron · easy · numerical
The columns of Bertini seen in a section of the human kidney are:
A. The pointed tips of pyramids projecting into the calyces
B. Extensions of the cortex that project inward between the medullary pyramids ✓ Correct
C. Bundles of collecting ducts running through the renal papilla
D. The outer fibrous capsule covering the kidney surface
Solution: The renal cortex dips down between the medullary pyramids as the renal (Bertini) columns; the pyramidal projections into the calyx are the renal papillae.
Q16 — Human Excretory System & Nephron · easy · numerical
Approximately how many nephrons are present in each human kidney?
A. About one thousand
B. About one million ✓ Correct
C. About ten thousand
D. About one billion
Solution: Each human kidney contains roughly one million (about ten lakh) nephrons, its structural and functional units.
Q17 — Human Excretory System & Nephron · easy · numerical
The vasa recta are:
A. The muscular ducts that carry urine to the bladder
B. The afferent arterioles supplying blood to the glomerulus
C. The filtration slits between adjacent podocytes
D. A network of capillaries running parallel to the loop of Henle ✓ Correct
Solution: The vasa recta are straight capillaries that run alongside the loop of Henle and are important in the counter-current concentration of urine.
Q18 — Human Excretory System & Nephron · easy · numerical
The renal corpuscle (Malpighian body) of a nephron consists of:
A. The glomerulus enclosed within the Bowman's capsule ✓ Correct
B. The loop of Henle together with the vasa recta
C. The proximal convoluted tubule and its brush border
D. The distal convoluted tubule joined to the collecting duct
Solution: The Malpighian body / renal corpuscle is the glomerulus (capillary tuft) held inside the cup-shaped Bowman's capsule, where filtration begins.
Q19 — Urine Formation · easy · numerical
The main force that drives fluid out of the glomerular capillaries into the Bowman's capsule is the:
A. Active pumping of water by the podocytes
B. Hydrostatic pressure of fluid already inside the capsule
C. Colloidal osmotic pressure of the plasma proteins
D. High glomerular (blood) hydrostatic pressure ✓ Correct
Solution: Filtration is driven by the high glomerular blood hydrostatic pressure, which is opposed by the plasma colloidal osmotic pressure and the capsular hydrostatic pressure.
Q20 — Urine Formation · easy · numerical
Of the total glomerular filtrate formed, the fraction reabsorbed back into the blood by the renal tubules is nearly:
A. 99 per cent ✓ Correct
B. 10 per cent
C. 25 per cent
D. 50 per cent
Solution: About 99% of the filtrate is reabsorbed by the tubules, so only around 1% is finally voided as urine.
Q21 — Urine Formation · easy · numerical
In a healthy person, glucose is normally absent from the urine because:
A. It is destroyed by enzymes present in the collecting duct
B. It is too large a molecule to pass through the filtration membrane
C. It is secreted back into the blood by the vasa recta
D. It is completely reabsorbed from the filtrate by active transport in the tubule ✓ Correct
Solution: Glucose is freely filtered but is entirely reabsorbed (mainly in the PCT) by active transport, so it does not normally appear in urine.
Q22 — Urine Formation · easy · numerical
Conditional (facultative) reabsorption of water and sodium ions, adjusted according to the body's needs, occurs mainly in the:
A. Glomerulus and Bowman's capsule
B. Distal convoluted tubule and collecting duct ✓ Correct
C. Afferent and efferent arterioles
D. Descending limb of the loop of Henle only
Solution: The DCT and collecting duct carry out conditional reabsorption under hormonal control (ADH, aldosterone), fine-tuning the final volume and concentration of urine.
Q23 — Regulation & Osmoregulation · easy · numerical
Antidiuretic hormone (ADH) concentrates the urine mainly by:
A. Blocking sodium reabsorption in the proximal tubule
B. Increasing water reabsorption from the distal tubule and collecting duct ✓ Correct
C. Increasing filtration by dilating the afferent arteriole
D. Promoting the loss of large amounts of dilute urine
Solution: ADH raises the water permeability of the DCT and collecting duct, so more water is reabsorbed and a smaller volume of concentrated urine is formed.
Q24 — Regulation & Osmoregulation · easy · numerical
The osmoreceptors that trigger the release of ADH in response to a rise in blood osmolarity are located in the:
A. Hypothalamus ✓ Correct
B. Wall of the atria
C. Adrenal cortex
D. Juxtaglomerular apparatus
Solution: Hypothalamic osmoreceptors detect the increased osmotic concentration (or fall in blood volume) and stimulate ADH release from the neurohypophysis.
Q25 — Regulation & Osmoregulation · easy · numerical
The urge for micturition (passing of urine) is normally triggered when:
A. The collecting duct becomes impermeable to water
B. The glomerulus stops filtering blood into the nephron
C. The kidneys secrete large amounts of renin into the blood
D. Stretch receptors in the wall of the filled urinary bladder are stimulated ✓ Correct
Solution: As the bladder fills, its stretched wall stimulates stretch receptors, sending signals to the CNS that produce the reflex urge to urinate (the micturition reflex).
Q26 — Regulation & Osmoregulation · easy · numerical
ADH is also known by the alternative name:
A. Vasopressin ✓ Correct
B. Angiotensinogen
C. Aldosterone
D. Oxytocin
Solution: Antidiuretic hormone is also called vasopressin because, besides promoting water reabsorption, it can constrict blood vessels and raise blood pressure.
Q27 — Disorders & Other Excretory Organs · easy · numerical
In an artificial kidney (haemodialysis) unit, the composition of the dialysing fluid is similar to that of plasma except that it:
A. Contains a very high concentration of urea
B. Lacks all glucose and mineral ions
C. Contains no nitrogenous wastes such as urea ✓ Correct
D. Is made up of pure distilled water only
Solution: The dialysing fluid matches plasma in ions and glucose but has no nitrogenous wastes, so urea and other wastes diffuse out of the blood into the fluid while useful substances are retained.
Q28 — Disorders & Other Excretory Organs · easy · numerical
Inflammation of the glomeruli of the kidney is medically termed:
A. Uremia
B. Glomerulonephritis ✓ Correct
C. Renal calculi
D. Cystitis
Solution: Glomerulonephritis is inflammation of the glomeruli, which impairs filtration; uremia is raised blood urea and renal calculi are kidney stones.
Q29 — Disorders & Other Excretory Organs · easy · numerical
Deposition of uric acid crystals in the joints, causing painful inflammation, results in the condition called:
A. Glomerulonephritis
B. Gout ✓ Correct
C. Uremia
D. Diabetes insipidus
Solution: Excess uric acid can crystallise in the joints and produce gout; this is distinct from uremia (blood urea build-up) and renal calculi (stones).
Q30 — Disorders & Other Excretory Organs · easy · numerical
Besides bile pigments, the liver contributes to excretion by removing from the blood substances such as:
A. Large amounts of sodium chloride through sweat
B. Cholesterol, degraded steroid hormones, vitamins and certain drugs ✓ Correct
C. Carbon dioxide and water vapour
D. Excess glucose directly into the urine
Solution: The liver eliminates cholesterol, inactivated steroid hormones, some vitamins and many drugs (along with bile pigments from haemoglobin breakdown) via the bile.