MCQs on Excretory Products and Their Elimination – Class 11
MCQs on Excretory Products and Their Elimination – CBSE Class 11 Biology (Unit V | NCERT-Based)
CBSE Class 11 Biology – MCQs with Answers and Explanations
Unit V: Human Physiology
Topic: Excretory Products and Their Elimination
Section A: Excretion & Nitrogenous Wastes (Q1–Q10)
Q1. Excretion is the process of:
A. Removal of undigested food
B. Removal of metabolic wastes
C. Removal of excess water only
D. Removal of gases
Answer: B
Explanation: Excretion eliminates metabolic waste products formed during cellular activities.
Q2. The main nitrogenous waste in humans is:
A. Ammonia
B. Uric acid
C. Urea
D. Creatinine
Answer: C
Explanation: Humans are ureotelic, excreting nitrogen mainly as urea.
Q3. Ammonia is excreted mainly by:
A. Mammals
B. Birds
C. Aquatic animals
D. Reptiles
Answer: C
Explanation: Aquatic animals are ammonotelic, releasing ammonia directly into water.
Q4. Birds and reptiles excrete nitrogen mainly as:
A. Urea
B. Ammonia
C. Uric acid
D. Creatinine
Answer: C
Explanation: Uric acid is less toxic and conserves water.
Q5. Urea is synthesized in the:
A. Kidney
B. Liver
C. Lungs
D. Spleen
Answer: B
Explanation: Urea is formed in the liver via the ornithine cycle.
Q6. The process of urea formation is called:
A. Glycolysis
B. Krebs cycle
C. Ornithine cycle
D. Calvin cycle
Answer: C
Explanation: The ornithine (urea) cycle converts ammonia into urea.
Q7. Which of the following is NOT an excretory product in humans?
A. Urea
B. Carbon dioxide
C. Bile pigments
D. Glucose
Answer: D
Explanation: Glucose is a useful nutrient, not an excretory waste.
Q8. Carbon dioxide is eliminated mainly by:
A. Kidneys
B. Skin
C. Lungs
D. Liver
Answer: C
Explanation: Lungs remove CO₂ during respiration.
Q9. Which organ helps in excretion of bile pigments?
A. Kidney
B. Liver
C. Skin
D. Lungs
Answer: B
Explanation: Liver excretes bile pigments via bile.
Q10. Excess salts and water are excreted by:
A. Lungs
B. Skin
C. Liver
D. Pancreas
Answer: B
Explanation: Sweat glands remove salts and water.
Section B: Human Excretory System & Kidney Structure (Q11–Q20)
Q11. The functional unit of kidney is:
A. Neuron
B. Nephron
C. Glomerulus
D. Tubule
Answer: B
Explanation: Nephrons carry out urine formation.
Q12. Each human kidney contains about:
A. 1 lakh nephrons
B. 5 lakh nephrons
C. 10 lakh nephrons
D. 50 lakh nephrons
Answer: C
Explanation: Each kidney has about 1 million nephrons.
Q13. Bowman’s capsule encloses the:
A. Loop of Henle
B. Collecting duct
C. Glomerulus
D. Proximal tubule
Answer: C
Explanation: Bowman’s capsule and glomerulus together form Malpighian corpuscle.
Q14. Ultrafiltration occurs in the:
A. Proximal tubule
B. Loop of Henle
C. Distal tubule
D. Glomerulus
Answer: D
Explanation: High blood pressure causes ultrafiltration in glomerulus.
Q15. Which blood vessel brings blood to the glomerulus?
A. Renal vein
B. Efferent arteriole
C. Afferent arteriole
D. Renal artery
Answer: C
Explanation: Afferent arteriole supplies blood for filtration.
Q16. The efferent arteriole is narrower than afferent arteriole to:
A. Reduce pressure
B. Increase pressure
C. Prevent backflow
D. Filter blood
Answer: B
Explanation: Narrow efferent arteriole maintains high filtration pressure.
Q17. Which part of nephron is present in renal medulla?
A. Bowman’s capsule
B. Proximal tubule
C. Loop of Henle
D. Glomerulus
Answer: C
Explanation: Loop of Henle dips into medulla.
Q18. Juxtaglomerular apparatus is involved in regulation of:
A. Respiration
B. Blood pressure
C. Digestion
D. Excretion of urea
Answer: B
Explanation: JGA regulates blood pressure and GFR.
Q19. Renal pelvis opens into the:
A. Kidney
B. Nephron
C. Ureter
D. Urinary bladder
Answer: C
Explanation: Urine flows from renal pelvis into ureter.
Q20. The kidneys are located in the:
A. Thoracic cavity
B. Pelvic cavity
C. Abdominal cavity
D. Cranial cavity
Answer: C
Explanation: Kidneys lie in the abdominal cavity.
Section C: Urine Formation & Regulation (Q21–Q35)
Q21. The first step of urine formation is:
A. Reabsorption
B. Secretion
C. Ultrafiltration
D. Osmoregulation
Answer: C
Explanation: Ultrafiltration occurs at the glomerulus.
Q22. Reabsorption of useful substances mainly occurs in:
A. Bowman’s capsule
B. Proximal convoluted tubule
C. Loop of Henle
D. Collecting duct
Answer: B
Explanation: PCT reabsorbs glucose, amino acids, ions, and water.
Q23. Which substance is normally NOT present in urine?
A. Urea
B. Uric acid
C. Glucose
D. Creatinine
Answer: C
Explanation: Presence of glucose indicates diabetes mellitus.
Q24. The loop of Henle is important for:
A. Ultrafiltration
B. Osmoregulation
C. Secretion
D. pH control
Answer: B
Explanation: Loop of Henle concentrates urine by counter-current mechanism.
Q25. Counter-current mechanism operates between:
A. PCT and DCT
B. Collecting duct and pelvis
C. Loop of Henle and vasa recta
D. Bowman’s capsule and PCT
Answer: C
Explanation: It maintains osmotic gradient in medulla.
Q26. Which hormone increases water reabsorption in kidneys?
A. Aldosterone
B. ADH
C. Thyroxine
D. Insulin
Answer: B
Explanation: ADH increases water permeability of collecting ducts.
Q27. Aldosterone regulates reabsorption of:
A. Glucose
B. Calcium
C. Sodium and potassium
D. Urea
Answer: C
Explanation: Aldosterone controls Na⁺ and K⁺ balance.
Q28. Decrease in ADH secretion results in:
A. Concentrated urine
B. Dilute urine
C. No urine
D. High blood pressure
Answer: B
Explanation: Less ADH leads to excess water loss.
Q29. Normal pH of urine is approximately:
A. 4.0
B. 5.0
C. 6.0
D. 8.0
Answer: C
Explanation: Normal urine pH is slightly acidic (~6).
Q30. Average volume of urine excreted per day is about:
A. 500 mL
B. 1–1.5 L
C. 3–4 L
D. 5 L
Answer: B
Explanation: Normal urine output is 1–1.5 liters/day.
Q31. Presence of ketone bodies in urine indicates:
A. Anemia
B. Starvation or diabetes
C. Kidney failure
D. Infection
Answer: B
Explanation: Ketone bodies appear during fat metabolism.
Q32. Micturition refers to:
A. Urine formation
B. Urine storage
C. Urine expulsion
D. Filtration
Answer: C
Explanation: Micturition is urination.
Q33. Urinary bladder opens to exterior through:
A. Ureter
B. Urethra
C. Nephron
D. Pelvis
Answer: B
Explanation: Urethra carries urine out of body.
Q34. Which structure stores urine temporarily?
A. Kidney
B. Ureter
C. Urinary bladder
D. Urethra
Answer: C
Explanation: Urinary bladder stores urine before expulsion.
Q35. Stretch receptors involved in micturition are present in:
A. Kidney
B. Ureter
C. Bladder wall
D. Urethra
Answer: C
Explanation: Stretch receptors trigger micturition reflex.
Section D: Disorders & Other Excretory Organs (Q36–Q50)
Q36. Kidney stone is medically called:
A. Nephritis
B. Renal calculi
C. Uremia
D. Albuminuria
Answer: B
Explanation: Renal calculi are solid deposits in kidneys.
Q37. Uremia refers to accumulation of:
A. Uric acid
B. Glucose
C. Urea in blood
D. Ketone bodies
Answer: C
Explanation: Kidney failure leads to urea accumulation.
Q38. Which condition shows presence of protein in urine?
A. Glycosuria
B. Hematuria
C. Albuminuria
D. Ketonuria
Answer: C
Explanation: Albuminuria indicates kidney damage.
Q39. Dialysis is required in case of:
A. Liver failure
B. Lung failure
C. Kidney failure
D. Heart failure
Answer: C
Explanation: Dialysis removes wastes when kidneys fail.
Q40. Artificial kidney works on principle of:
A. Filtration
B. Osmosis
C. Diffusion
D. Ultrafiltration
Answer: C
Explanation: Dialysis removes wastes by diffusion.
Q41. Which organ excretes sweat?
A. Liver
B. Skin
C. Kidney
D. Lungs
Answer: B
Explanation: Sweat glands excrete water and salts.
Q42. Which organ helps in excretion of CO₂ and water vapour?
A. Skin
B. Kidneys
C. Lungs
D. Liver
Answer: C
Explanation: Lungs eliminate CO₂ and water vapour.
Q43. Jaundice is caused due to accumulation of:
A. Urea
B. Bile pigments
C. Creatinine
D. Glucose
Answer: B
Explanation: Excess bilirubin causes yellowing of skin.
Q44. Excessive urine output is called:
A. Oliguria
B. Anuria
C. Polyuria
D. Dysuria
Answer: C
Explanation: Polyuria indicates excess urine formation.
Q45. Anuria refers to:
A. Painful urination
B. Frequent urination
C. Absence of urine formation
D. Blood in urine
Answer: C
Explanation: Anuria indicates severe kidney failure.
Q46. Blood in urine is termed as:
A. Albuminuria
B. Glycosuria
C. Hematuria
D. Ketonuria
Answer: C
Explanation: Hematuria indicates injury or infection.
Q47. Which waste is excreted by lungs?
A. Urea
B. Uric acid
C. Carbon dioxide
D. Creatinine
Answer: C
Explanation: CO₂ is eliminated during exhalation.
Q48. Kidneys help maintain:
A. Body temperature only
B. Osmotic balance and pH
C. Digestion
D. Respiration
Answer: B
Explanation: Kidneys regulate osmoregulation and acid-base balance.
Q49. Which hormone increases blood pressure by acting on kidneys?
A. ADH
B. Aldosterone
C. Renin
D. Insulin
Answer: C
Explanation: Renin initiates RAAS system.
Q50. Excretion is essential because it:
A. Produces energy
B. Maintains homeostasis
C. Aids digestion
D. Helps reproduction
Answer: B
Explanation: Removal of wastes maintains internal balance of body.