Question Bank — Excretory Products and their Elimination

NCERT Class 11 Biology · Chapter 16 · CBSE Board Pattern

Class 11 Biology Chapter 16 Question Bank CBSE Board Pattern

Section A — MCQs (10 questions, 1 mark each)

  1. Which of the following animals is ammonotelic?
    (a) Birds
    (b) Mammals
    (c) Bony fishes
    (d) Land snails

  2. The functional unit of the human kidney is:
    (a) Neuron
    (b) Nephron
    (c) Malpighian tubule
    (d) Protonephridia

  3. Assertion (A): Ammonia is the most toxic nitrogenous waste and requires large amounts of water for its elimination.
    Reason (R): Uric acid is the least toxic nitrogenous waste and can be removed with minimum loss of water.
    (a) Both A and R are true and R is the correct explanation of A.
    (b) Both A and R are true but R is not the correct explanation of A.
    (c) A is true but R is false.
    (d) A is false but R is true.

  4. The glomerular filtration rate (GFR) in a healthy adult human is approximately:
    (a) 125 ml/min
    (b) 180 ml/min
    (c) 1.5 litres/min
    (d) 1200 ml/min

  5. Assertion (A): The ascending limb of the loop of Henle is impermeable to water but allows transport of electrolytes.
    Reason (R): This helps in maintaining the high osmolarity of the medullary interstitial fluid.
    (a) Both A and R are true and R is the correct explanation of A.
    (b) Both A and R are true but R is not the correct explanation of A.
    (c) A is true but R is false.
    (d) A is false but R is true.

  6. Which structure is absent or highly reduced in cortical nephrons?
    (a) Bowman’s capsule
    (b) Proximal convoluted tubule
    (c) Vasa recta
    (d) Collecting duct

  7. The process of release of urine is called:
    (a) Ultrafiltration
    (b) Micturition
    (c) Osmoregulation
    (d) Counter current mechanism

  8. Juxtaglomerular apparatus (JGA) is formed by modifications in:
    (a) PCT and efferent arteriole
    (b) DCT and afferent arteriole
    (c) Loop of Henle and vasa recta
    (d) Collecting duct and peritubular capillaries

  9. Which of the following is not a nitrogenous waste excreted by humans?
    (a) Urea
    (b) Uric acid
    (c) Ammonia
    (d) Bilirubin

  10. The counter current mechanism operates between:
    (a) PCT and DCT
    (b) Two limbs of Henle’s loop and two limbs of vasa recta
    (c) Glomerulus and Bowman’s capsule
    (d) Collecting duct and renal pelvis

Section B — Very Short Answer (6 questions, 2 marks each)

  1. Differentiate between ammonotelic and uricotelic animals with one example of each.
  2. What is the role of podocytes in glomerular filtration?
  3. State two functions of the proximal convoluted tubule (PCT).
  4. Define osmoregulation. Name the excretory structure in earthworms.
  5. What is the significance of the counter current mechanism in the kidney?
  6. Name the organs (other than kidney) involved in excretion in humans and mention one waste eliminated by each.

Section C — Short Answer (5 questions, 3 marks each)

  1. Describe the three main processes involved in urine formation.
  2. Explain the role of ADH in regulation of kidney function.
  3. Write a short note on micturition reflex.
  4. How does the loop of Henle contribute to the concentration of urine?
  5. Differentiate between cortical nephrons and juxtamedullary nephrons.

Section D — Long Answer (3 questions, 5 marks each)

  1. Describe the structure of a nephron with the help of a labelled diagram. (Diagram description required)
  2. Explain the counter current mechanism operating in the kidney. How does it help in concentrating the urine?
  3. Describe the role of liver, lungs and skin in excretion in humans.

Section E — Case/Source-Based (2 questions, 4 marks each)

Case 1: A patient shows symptoms of uremia due to kidney malfunction. Doctors recommend hemodialysis as a temporary measure.

(a) What is uremia?
(b) Explain the principle of hemodialysis.
(c) Why is heparin added during the process?
(d) Name the ultimate method for correction of acute renal failure.

Case 2: An adult human excretes about 1–1.5 litres of urine daily. The urine is light yellow, slightly acidic (pH 6.0) and contains 25–30 g of urea. Presence of glucose or ketone bodies indicates a metabolic disorder.

(a) What is the normal daily volume of urine in a healthy adult?
(b) Name the condition indicated by glucose in urine.
(c) State the role of collecting duct in urine concentration.
(d) How does analysis of urine help in clinical diagnosis?

▶ Answer Key Attempt all questions first,
then tap to reveal

Section A

  1. (c)
  2. (b)
  3. (b)
  4. (a)
  5. (a)
  6. (c)
  7. (b)
  8. (b)
  9. (d)
  10. (b)

Section B

  1. Ammonotelic excrete ammonia (e.g., bony fishes); uricotelic excrete uric acid (e.g., birds) — 1 mark each.
  2. Podocytes form filtration slits allowing passage of plasma components except proteins — 2 marks.
  3. Reabsorbs 70–80% water/electrolytes/nutrients; maintains pH by secreting H+ and NH3 — 1.5 + 1.5 marks.
  4. Maintenance of ionic/fluid balance; nephridia in earthworms — 1 + 1 mark.
  5. Maintains medullary osmolarity gradient (300–1200 mOsmolL–1) for water reabsorption — 2 marks.
  6. Lungs (CO2), liver (bilirubin via bile), skin (urea/NaCl via sweat) — 0.5 × 4 = 2 marks.

Section C

  1. Glomerular filtration, reabsorption (99%), tubular secretion — 1 mark each.
  2. ADH released by hypothalamus increases water reabsorption in DCT/collecting duct; prevents diuresis — 3 marks.
  3. Stretch of bladder → CNS signal → bladder contraction + urethral sphincter relaxation — 3 marks.
  4. Descending limb permeable to water (concentrates filtrate); ascending limb transports electrolytes (dilutes filtrate) — 3 marks.
  5. Cortical: short loop, vasa recta reduced; juxtamedullary: long loop deep into medulla — 3 marks.

Section D

  1. Nephron parts: Malpighian corpuscle, PCT, loop of Henle, DCT, collecting duct + labelled diagram description — definition 1, parts 3, diagram 1.
  2. Counter current in Henle’s loop & vasa recta creates 300–1200 mOsmolL–1 gradient via NaCl/urea; enables water reabsorption — 5 marks.
  3. Lungs (CO2 ~200 ml/min), liver (bile pigments), skin (sweat: NaCl, urea) — 5 marks.

Section E

Case 1: (a) Accumulation of urea in blood — 1 mark; (b) Blood passed through dialysing unit with semipermeable membrane — 1 mark; (c) Prevents clotting — 1 mark; (d) Kidney transplantation — 1 mark.
Case 2: (a) 1–1.5 litres — 1 mark; (b) Glycosuria (diabetes mellitus) — 1 mark; (c) Reabsorbs water, secretes H+/K+ — 1 mark; (d) Detects metabolic disorders like diabetes — 1 mark.

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All questions are answerable from the NCERT chapter text. Reviewed by GFIS faculty.