Part 1: Excretory Products and Modes of Excretion
200 Multiple-Choice Questions (MCQs) from Chapter 19 – Excretory Products and Their Elimination of NCERT Class 11 Biology.
Subtopics (as per NCERT & NEET relevance):
- Introduction & Excretory Products – Ammonotelism, Ureotelism, Uricotelism
- Human Excretory System – Structure of Kidney, Nephron, Renal Circulation
- Urine Formation – Ultrafiltration, Reabsorption, Secretion
- Counter-Current Mechanism & Osmoregulation
- Regulation of Kidney Function – Hormonal Control (ADH, Aldosterone, ANF, Renin–Angiotensin)
- Micturition & Role of Other Organs in Excretion
- Disorders of the Excretory System – Uremia, Renal Failure, Kidney Stones, etc.
- Miscellaneous & Integrated Questions for NEET-Level Practice
Part 1 (25 MCQs) on Excretory Products & Modes of Excretion (Ammonotelism, Ureotelism, Uricotelism, General Introduction).
Part 1: Excretory Products and Modes of Excretion
Q1. Which of the following organisms are ammonotelic?
a) Mammals
b) Birds
c) Amphibians
d) Reptiles
Answer: c) Amphibians
Explanation:
- (a) Mammals – ureotelic (excrete urea).
- (b) Birds – uricotelic (excrete uric acid).
- ✅ (c) Amphibians – ammonotelic in water (ammonia excretion).
- (d) Reptiles – uricotelic.
Q2. Which of the following is the most toxic nitrogenous waste?
a) Ammonia
b) Urea
c) Uric acid
d) Creatinine
Answer: a) Ammonia
Explanation:
- ✅ (a) Ammonia – highly toxic, requires lots of water for excretion.
- (b) Urea – less toxic, requires less water.
- (c) Uric acid – least toxic, excreted as paste.
- (d) Creatinine – metabolic byproduct, less toxic than ammonia.
Q3. Which of the following is least soluble in water?
a) Urea
b) Ammonia
c) Uric acid
d) Creatinine
Answer: c) Uric acid
Explanation:
- (a) Urea – highly soluble.
- (b) Ammonia – highly soluble.
- ✅ (c) Uric acid – poorly soluble, excreted as crystals.
- (d) Creatinine – soluble.
Q4. In humans, the major nitrogenous waste is:
a) Ammonia
b) Urea
c) Uric acid
d) Guanine
Answer: b) Urea
Explanation:
- (a) Ammonia – excreted in trace amounts.
- ✅ (b) Urea – major excretory product in humans.
- (c) Uric acid – excreted in small amounts.
- (d) Guanine – excreted in some arachnids, not humans.
Q5. Which of the following is uricotelic?
a) Fish
b) Amphibians
c) Birds
d) Mammals
Answer: c) Birds
Explanation:
- (a) Fish – mostly ammonotelic.
- (b) Amphibians – ammonotelic in water, ureotelic on land.
- ✅ (c) Birds – uricotelic.
- (d) Mammals – ureotelic.
Q6. Which statement about ammonotelism is correct?
a) It requires the least water
b) It is common in mammals
c) Ammonia is highly toxic
d) Uric acid is excreted
Answer: c) Ammonia is highly toxic
Explanation:
- (a) Wrong – requires maximum water.
- (b) Wrong – mammals are ureotelic.
- ✅ (c) Ammonia is highly toxic.
- (d) Wrong – uric acid is not excreted in ammonotelism.
Q7. Ureotelism is an adaptation to:
a) Aquatic environment
b) Terrestrial environment with limited water
c) Desert environment
d) Marine environment
Answer: b) Terrestrial environment with limited water
Explanation:
- (a) Wrong – aquatic animals are ammonotelic.
- ✅ (b) Correct – mammals and amphibians on land.
- (c) Wrong – desert animals are uricotelic.
- (d) Wrong – marine bony fishes are ureotelic but with special adaptations.
Q8. Uric acid excretion conserves maximum:
a) Oxygen
b) Water
c) Urea
d) Sodium
Answer: b) Water
Explanation:
- (a) Oxygen – unrelated.
- ✅ (b) Water – uricotelism conserves water by excreting crystals.
- (c) Urea – not relevant.
- (d) Sodium – not directly conserved.
Q9. In which animals is guanine the main excretory product?
a) Birds
b) Reptiles
c) Mammals
d) Spiders
Answer: d) Spiders
Explanation:
- (a) Birds – uric acid.
- (b) Reptiles – uric acid.
- (c) Mammals – urea.
- ✅ (d) Spiders – guanine.
Q10. Which waste product is produced during creatine metabolism?
a) Uric acid
b) Creatinine
c) Urea
d) Ammonia
Answer: b) Creatinine
Explanation:
- (a) Uric acid – purine metabolism.
- ✅ (b) Creatinine – byproduct of creatine metabolism.
- (c) Urea – amino acid metabolism.
- (d) Ammonia – amino acid deamination.
Q11. Sharks are:
a) Ammonotelic
b) Ureotelic
c) Uricotelic
d) Guanotelic
Answer: b) Ureotelic
Explanation:
- (a) Ammonotelic – true for most fishes, not sharks.
- ✅ (b) Sharks are ureotelic.
- (c) Uricotelic – false.
- (d) Guanotelic – spiders, not sharks.
Q12. Which of the following is mammalian adaptation for water conservation?
a) Ammonotelism
b) Ureotelism
c) Uricotelism
d) Anaerobic metabolism
Answer: b) Ureotelism
Explanation:
- (a) Ammonotelism – aquatic adaptation.
- ✅ (b) Ureotelism – mammals excrete urea.
- (c) Uricotelism – reptiles & birds.
- (d) Anaerobic metabolism – unrelated.
Q13. In birds, nitrogenous waste is eliminated as:
a) Urea dissolved in urine
b) Uric acid crystals with feces
c) Ammonia in gaseous form
d) Creatinine in urine
Answer: b) Uric acid crystals with feces
Explanation:
- (a) Wrong – urea not main product.
- ✅ (b) Birds excrete uric acid crystals (pasty, white).
- (c) Wrong – ammonia not excreted as gas.
- (d) Wrong – creatinine not major.
Q14. Which organism is ureotelic?
a) Frog on land
b) Tadpole
c) Bird
d) Lizard
Answer: a) Frog on land
Explanation:
- ✅ (a) Frog on land – ureotelic.
- (b) Tadpole – ammonotelic.
- (c) Bird – uricotelic.
- (d) Lizard – uricotelic.
Q15. The chief excretory product in insects is:
a) Ammonia
b) Urea
c) Uric acid
d) Creatinine
Answer: c) Uric acid
Explanation:
- (a) Ammonia – aquatic animals.
- (b) Urea – mammals.
- ✅ (c) Insects are uricotelic.
- (d) Creatinine – humans.
Q16. Which of the following requires maximum water for excretion?
a) Uricotelic organisms
b) Ureotelic organisms
c) Ammonotelic organisms
d) Guanotelic organisms
Answer: c) Ammonotelic organisms
Explanation:
- (a) Wrong – uricotelic conserve water.
- (b) Wrong – ureotelic moderate water.
- ✅ (c) Ammonotelic – excrete ammonia, needs lots of water.
- (d) Wrong – guanine is excreted as crystals.
Q17. Amphibians are:
a) Ammonotelic only
b) Ureotelic only
c) Uricotelic only
d) Both ammonotelic and ureotelic
Answer: d) Both ammonotelic and ureotelic
Explanation:
- (a) Wrong – not only ammonotelic.
- (b) Wrong – not only ureotelic.
- (c) Wrong – uricotelic not seen.
- ✅ (d) Aquatic amphibians ammonotelic, terrestrial ureotelic.
Q18. Which excretory product has highest energy cost?
a) Ammonia
b) Urea
c) Uric acid
d) Creatinine
Answer: c) Uric acid
Explanation:
- (a) Ammonia – no energy cost.
- (b) Urea – moderate energy cost.
- ✅ (c) Uric acid – highest ATP requirement.
- (d) Creatinine – not primary excretory.
Q19. Reptiles excrete:
a) Ammonia
b) Urea
c) Uric acid
d) Guanine
Answer: c) Uric acid
Explanation:
- (a) Wrong – aquatic excretion.
- (b) Wrong – mammals.
- ✅ (c) Reptiles – uricotelic.
- (d) Wrong – spiders excrete guanine.
Q20. Which is a non-toxic nitrogenous waste?
a) Ammonia
b) Urea
c) Uric acid
d) Both b and c
Answer: d) Both b and c
Explanation:
- (a) Ammonia – toxic.
- ✅ (b) Urea – relatively non-toxic.
- ✅ (c) Uric acid – least toxic.
- (d) Correct.
Q21. Which nitrogenous waste is formed by purine metabolism?
a) Urea
b) Uric acid
c) Ammonia
d) Creatinine
Answer: b) Uric acid
Explanation:
- (a) Urea – amino acid metabolism.
- ✅ (b) Uric acid – from purines.
- (c) Ammonia – amino acid deamination.
- (d) Creatinine – creatine metabolism.
Q22. Human beings excrete:
a) Only urea
b) Urea mainly, with uric acid and creatinine
c) Only ammonia
d) Only creatinine
Answer: b) Urea mainly, with uric acid and creatinine
Explanation:
- (a) Wrong – not only urea.
- ✅ (b) Correct – urea major, also uric acid, creatinine.
- (c) Wrong – ammonia minor only.
- (d) Wrong – creatinine not major.
Q23. Which of the following excretes allantoin?
a) Reptiles
b) Amphibians
c) Mammals (except humans)
d) Fish
Answer: c) Mammals (except humans)
Explanation:
- (a) Wrong – reptiles uricotelic.
- (b) Wrong – amphibians ureotelic/ammonotelic.
- ✅ (c) Many mammals excrete allantoin, humans excrete uric acid.
- (d) Wrong – fish mostly ammonotelic.
Q24. Which nitrogenous waste is least toxic?
a) Ammonia
b) Urea
c) Uric acid
d) Creatinine
Answer: c) Uric acid
Explanation:
- (a) Ammonia – most toxic.
- (b) Urea – moderate toxicity.
- ✅ (c) Uric acid – least toxic.
- (d) Creatinine – less toxic but not main.
Q25. Which excretory mode is most energy-efficient?
a) Ammonotelism
b) Ureotelism
c) Uricotelism
d) Guanotelism
Answer: a) Ammonotelism
Explanation:
- ✅ (a) Ammonotelism – no ATP required.
- (b) Ureotelism – requires ATP.
- (c) Uricotelism – requires highest ATP.
- (d) Guanotelism – also requires energy.
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