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Excretory Products and Their Elimination — NEET Biology MCQs

30 questions written by hand against the NCERT chapter. Every wrong option is explained, not just the right one.

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Sample questions from this chapter

An aquatic animal can continuously exchange water with its surroundings and releases nitrogenous waste across its gills. Which waste is best suited to this mode of excretion?
  1. Ammonia, because its high toxicity is offset by rapid dilution in abundant water ✓
  2. Urea, because converting ammonia to urea requires the least metabolic processing
  3. Uric acid, because its poor solubility favours diffusion across wet gills
  4. Creatinine, because it is the principal nitrogenous waste of bony fishes
Answer: A. Ammonia is very toxic but readily soluble, so many aquatic animals eliminate it rapidly as ammonium ions across body or gill surfaces. Urea is the tempting terrestrial alternative because it is less toxic, but its synthesis is an added cost when water is plentiful.
Why not B: Urea conserves water but costs energy to synthesise, so it is common where ammonia cannot be safely diluted.
Why not C: Uric acid is adapted for excretion as a paste or pellet rather than rapid diffusion across gills.
Why not D: Students may associate creatinine with renal tests, but it is not the dominant nitrogenous waste described for bony fishes.
Inflammation damages the podocyte filtration slits while glomerular blood pressure remains normal. Which change is most directly expected?
  1. Increased active secretion of glucose by the PCT
  2. Conversion of urea back to ammonia in the liver
  3. Altered selectivity of ultrafiltration, allowing abnormal protein loss ✓
  4. Failure of the ureter to propel urine
Answer: C. Podocyte slits are part of the three-layer glomerular filter, so their damage can permit proteins to enter filtrate. A normal filtration pressure does not guarantee normal filtration selectivity.
Why not A: Glucose is normally reabsorbed from filtrate; podocyte injury does not turn it into a PCT secretory product.
Why not B: The liver forms urea from ammonia, a metabolic pathway separate from slit integrity.
Why not D: Ureteric peristalsis is downstream and can remain intact despite a damaged glomerular barrier.
A toxin selectively blocks NaCl transport from the ascending limb of Henle while water permeability of both limbs remains normal for their segment. What is the most likely consequence?
  1. A weaker medullary osmotic gradient and reduced capacity to concentrate urine ✓
  2. A stronger medullary gradient because salt remains in the tubular fluid
  3. Direct cessation of glomerular filtration despite normal glomerular pressure
  4. Increased PCT protein filtration through enlarged slit pores
Answer: A. Ascending-limb NaCl export is a major source of the medullary interstitial gradient. Blocking it leaves less osmotic force for ADH-sensitive water reabsorption, even though the descending limb can still lose some water locally.
Why not B: Salt retained in the tubule does not raise medullary interstitial osmolarity where it is needed to draw water from collecting ducts.
Why not C: Ascending-limb transport shapes concentration downstream but is not the pressure source for glomerular ultrafiltration.
Why not D: Podocyte slit selectivity is anatomically upstream and is not controlled by loop salt transport.

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Questions

How many NEET questions are there on Excretory Products and Their Elimination?

This chapter test has 30 questions — 10 easy, 14 medium and 6 hard — all written against the NCERT Class 11 chapter.

Is this NEET Biology chapter test free?

Yes. Every chapter test is free with no login. The only paid thing on the site is the full-length 90-question Biology mock and its all-India rank.

Do the questions explain the wrong options?

Yes — every distractor carries its own explanation naming the specific misconception that makes a student pick it. That is the part most question banks skip, and it is the part that changes your next attempt.