Excretory System - Competency-Based Question Bank (with Answers)

Section A: Case-Based Questions

Case Study 1: Person in desert with limited water, concentrated yellow urine.

Identify the hormone.
- Answer: ADH (Anti-Diuretic Hormone) or Vasopressin.
Target site of the hormone.
- Answer: Distal Convoluted Tubule (DCT) and Collecting Duct.
Designing: Predict change after drinking water.
- Answer: Urine will become dilute (hypotonic) and large in volume as ADH secretion decreases.
Analysis: Osmoregulation.
- Answer: The process of maintaining the constant osmotic pressure/water-salt balance of the blood.
Why yellow?
- Answer: Presence of Urochrome, a pigment formed from the breakdown of hemoglobin.

Case Study 2: Patient undergoing Haemodialysis. 6. Principle of dialysis.

Answer: Diffusion/Osmosis across a semi-permeable (cellophane) membrane.

Why compose fluid like plasma without waste?
- Answer: To create a concentration gradient so nitrogenous wastes (Urea) move from blood to fluid, while essential nutrients remain in the blood.
Creating: Dialysis diagram.
- Answer: [Description: Blood pumped from artery through tubes in a tank of dialysing fluid, then returned to a vein].
Critical Thinking: Why not a permanent cure?
- Answer: It only filters waste; it cannot perform other kidney functions like hormone production (Erythropoietin) or active regulation. Kidney transplant is the permanent solution.
Survive with one kidney?
- Answer: Yes. The remaining kidney undergoes compensatory hypertrophy (increases in size and function) to handle the load.

Section B: Assertion-Reasoning Questions

Directions: (a) Both A/R true, R explains A; (b) Both true, R doesn't explain A; (c) A true, R false; (d) A false, R true.

Assertion (A): Efferent arteriole is narrower than afferent. Reason (R): Creates high hydrostatic pressure for ultrafiltration.
- Answer: (a) Both A and R are true and R is the correct explanation.
Assertion (A): Glucose is not in normal urine. Reason (R): It is completely reabsorbed in PCT.
- Answer: (a) Both A and R are true and R is the correct explanation.
Assertion (A): Urine is slightly acidic. Reason (R): Secretion of H+ ions into filtrate.
- Answer: (a) Both A and R are true and R is the correct explanation.
Assertion (A): Liver is an excretory organ. Reason (R): It produces urea.
- Answer: (a) Both A and R are true and R is the correct explanation.
Assertion (A): Alcohol leads to frequent urination. Reason (R): Alcohol inhibits ADH.
- Answer: (a) Both A and R are true and R is the correct explanation.

Section C: Creating and Designing (Application & Analysis)

Designing: Steps of urine formation flowchart.
- Answer: Glomerulus (Ultrafiltration) -> PCT/Henle/DCT (Selective Reabsorption) -> DCT/Collecting Duct (Tubular Secretion) -> Urine.
Creating: Nephron Map.
- Answer: [PCT: Glucose, Amino acids, 65% water. Loop of Henle: Water (descending), Salts (ascending). DCT: Salts and Water (facultative)].
Analysis: Filtrate vs Urine.
- Answer: Filtrate contains glucose/amino acids; urine does not. Proteins are absent in both because they are too large to pass the glomerular filter.
Designing: Table of waste products.
- Answer: [Urea: Protein metabolism. Uric acid: Nucleic acid metabolism. Creatinine: Muscle metabolism].
Visualisation: Malpighian Body diagram.
- Answer: [Description: Cup-like Bowman's capsule surrounding a tuft of capillaries].
Application: Drink water in summer.
- Answer: To compensate for water lost through sweating (thermoregulation) and prevent dehydration/concentrated urine.
Creating: Glomerulus mimic.
- Answer: A high-pressure pump pushing liquid through an ultra-fine mesh filter.
Analysis: Threshold Substance.
- Answer: A substance reabsorbed efficiently by the kidney. Glucose is "high-threshold" because it's only excreted if its blood level exceeds a certain limit (Renal threshold).
Designing: Kidney stone diet.
- Answer: Avoid spinach, tomatoes, and nuts (high in oxalates). Increase water intake.
Creating: Kidney-Brain dialogue.
- Answer: Kidney: "Hey Brain, the blood is too salty!" Brain: "Copy that, releasing ADH now. Hold onto that water!"

Section D: Competency & Critical Thinking

Ultrafiltration.
- Answer: Filtration under high pressure where almost all liquid components (except proteins/cells) are forced out.
Scenario: Blood in urine (Haematuria).
- Answer: Possible kidney stone or infection causing damage to the urinary tract lining.
Critical Thinking: Ammonia vs Urea.
- Answer: Ammonia is highly toxic and needs lots of water to flush; suitable for fish. Urea is less toxic and conserves water; suitable for land mammals.
Application: Gout.
- Answer: Inflammation of joints due to accumulation of Uric acid crystals.
Excretion vs Egestion.
- Answer: Excretion: Removal of metabolic waste from cells. Egestion: Removal of undigested food from the gut.
Diagram Based: Urinary system.
- Answer: Sphincter muscles control the release of urine from the bladder (voluntary control).
Skin in excretion.
- Answer: Sweat glands remove water, salts, and small amounts of urea.
Analysis: Right kidney lower.
- Answer: Due to the large space occupied by the liver on the right side.
Competency: Counter-current mechanism.
- Answer: The flow of filtrate in opposite directions in the two limbs of the Loop of Henle helps build an osmotic gradient in the medulla to concentrate urine.
Case: High protein effect.
- Answer: More protein -> More deamination in liver -> More Urea in blood -> More Urea in urine.
Creating: Caffeine hypothesis.
- Answer: Caffeine increases blood flow to kidneys and inhibits ADH, increasing urine output.
Designing: Deamination visual.
- Answer: Amino Acid -> Ammonia ( $NH_3$ ) -> Ornithine Cycle -> Urea.
Application: pH maintenance.
- Answer: Kidneys secrete H+ ions and reabsorb $HCO_3^-$ ions to keep blood pH constant (approx 7.4).
Critical Thinking: Is urine sterile?
- Answer: Yes, inside a healthy bladder, but it picks up bacteria as it exits the body.
Analysis: Micturition.
- Answer: The act of passing urine. It is a reflex initiated by stretch receptors, but controllable by the brain.

Section E: Advanced Competency

Scenario: Diabetes Insipidus.
- Answer: Deficiency of ADH. Different from Mellitus (Insulin deficiency/Sugar). "Insipidus" means tasteless urine.
Designing: Model.
- Answer: Funnel (Capsule), Plastic tube (Nephron), Bottle (Bladder).
Application: Shivering while urinating in cold.
- Answer: Emptying a warm bladder causes a sudden drop in core temperature; shivering generates heat to compensate.
Creating: Crossword.
- Answer: [Terms: Cortex (Outer), Medulla (Inner), Hilum (Notch)].
Case Study: Hydronephrosis.
- Answer: Back-pressure of urine causes the kidney to swell and tissue to atrophy.
JGA role.
- Answer: Detects low BP and releases Renin, which leads to vasoconstriction and salt/water retention to raise BP.
Critical Thinking: Longer Loop of Henle.
- Answer: Allows for greater water reabsorption, producing highly concentrated urine for water conservation.
Analysis: Cortical vs Juxtamedullary.
- Answer: Cortical: Loop of Henle is short. Juxtamedullary: Loop of Henle is long and deep in medulla (for concentrating urine).
Designing: Urea concentration graph.
- Answer: High in Renal Artery, significantly lower in Renal Vein.
Creating: Smart Toilet parameters.
- Answer: Protein (Kidney health), Glucose (Diabetes), pH, Specific Gravity (Hydration).

Section A: Case-Based Questions

Case Study 1: Person in desert with limited water, concentrated yellow urine.

Identify the hormone.

Answer: ADH (Anti-Diuretic Hormone) or Vasopressin.

Target site of the hormone.

Answer: Distal Convoluted Tubule (DCT) and Collecting Duct.

Designing: Predict change after drinking water.

Answer: Urine will become dilute (hypotonic) and large in volume as ADH secretion decreases.

Analysis: Osmoregulation.

Answer: The process of maintaining the constant osmotic pressure/water-salt balance of the blood.

Why yellow?

Answer: Presence of Urochrome, a pigment formed from the breakdown of hemoglobin.

Case Study 2: Patient undergoing Haemodialysis. 6. Principle of dialysis.

Answer: Diffusion/Osmosis across a semi-permeable (cellophane) membrane.

Why compose fluid like plasma without waste?

Answer: To create a concentration gradient so nitrogenous wastes (Urea) move from blood to fluid, while essential nutrients remain in the blood.

Creating: Dialysis diagram.

Answer: [Description: Blood pumped from artery through tubes in a tank of dialysing fluid, then returned to a vein].

Critical Thinking: Why not a permanent cure?

Answer: It only filters waste; it cannot perform other kidney functions like hormone production (Erythropoietin) or active regulation. Kidney transplant is the permanent solution.

Survive with one kidney?

Answer: Yes. The remaining kidney undergoes compensatory hypertrophy (increases in size and function) to handle the load.

Section B: Assertion-Reasoning Questions

Directions: (a) Both A/R true, R explains A; (b) Both true, R doesn't explain A; (c) A true, R false; (d) A false, R true.

Assertion (A): Efferent arteriole is narrower than afferent. Reason (R): Creates high hydrostatic pressure for ultrafiltration.

Answer: (a) Both A and R are true and R is the correct explanation.

Assertion (A): Glucose is not in normal urine. Reason (R): It is completely reabsorbed in PCT.

Answer: (a) Both A and R are true and R is the correct explanation.

Assertion (A): Urine is slightly acidic. Reason (R): Secretion of H+ ions into filtrate.

Answer: (a) Both A and R are true and R is the correct explanation.

Assertion (A): Liver is an excretory organ. Reason (R): It produces urea.

Answer: (a) Both A and R are true and R is the correct explanation.

Assertion (A): Alcohol leads to frequent urination. Reason (R): Alcohol inhibits ADH.

Answer: (a) Both A and R are true and R is the correct explanation.

Section C: Creating and Designing (Application & Analysis)

Designing: Steps of urine formation flowchart.

Answer: Glomerulus (Ultrafiltration) -> PCT/Henle/DCT (Selective Reabsorption) -> DCT/Collecting Duct (Tubular Secretion) -> Urine.

Creating: Nephron Map.

Answer: [PCT: Glucose, Amino acids, 65% water. Loop of Henle: Water (descending), Salts (ascending). DCT: Salts and Water (facultative)].

Analysis: Filtrate vs Urine.

Answer: Filtrate contains glucose/amino acids; urine does not. Proteins are absent in both because they are too large to pass the glomerular filter.

Designing: Table of waste products.

Answer: [Urea: Protein metabolism. Uric acid: Nucleic acid metabolism. Creatinine: Muscle metabolism].

Visualisation: Malpighian Body diagram.

Answer: [Description: Cup-like Bowman's capsule surrounding a tuft of capillaries].

Application: Drink water in summer.

Answer: To compensate for water lost through sweating (thermoregulation) and prevent dehydration/concentrated urine.

Creating: Glomerulus mimic.

Answer: A high-pressure pump pushing liquid through an ultra-fine mesh filter.

Analysis: Threshold Substance.

Answer: A substance reabsorbed efficiently by the kidney. Glucose is "high-threshold" because it's only excreted if its blood level exceeds a certain limit (Renal threshold).

Designing: Kidney stone diet.

Answer: Avoid spinach, tomatoes, and nuts (high in oxalates). Increase water intake.

Creating: Kidney-Brain dialogue.

Answer: Kidney: "Hey Brain, the blood is too salty!" Brain: "Copy that, releasing ADH now. Hold onto that water!"

Section D: Competency & Critical Thinking

Ultrafiltration.

Answer: Filtration under high pressure where almost all liquid components (except proteins/cells) are forced out.

Scenario: Blood in urine (Haematuria).

Answer: Possible kidney stone or infection causing damage to the urinary tract lining.

Critical Thinking: Ammonia vs Urea.

Answer: Ammonia is highly toxic and needs lots of water to flush; suitable for fish. Urea is less toxic and conserves water; suitable for land mammals.

Application: Gout.

Answer: Inflammation of joints due to accumulation of Uric acid crystals.

Excretion vs Egestion.

Answer: Excretion: Removal of metabolic waste from cells. Egestion: Removal of undigested food from the gut.

Diagram Based: Urinary system.

Answer: Sphincter muscles control the release of urine from the bladder (voluntary control).

Skin in excretion.

Answer: Sweat glands remove water, salts, and small amounts of urea.

Analysis: Right kidney lower.

Answer: Due to the large space occupied by the liver on the right side.

Competency: Counter-current mechanism.

Answer: The flow of filtrate in opposite directions in the two limbs of the Loop of Henle helps build an osmotic gradient in the medulla to concentrate urine.

Case: High protein effect.

Answer: More protein -> More deamination in liver -> More Urea in blood -> More Urea in urine.

Creating: Caffeine hypothesis.

Answer: Caffeine increases blood flow to kidneys and inhibits ADH, increasing urine output.

Designing: Deamination visual.

Answer: Amino Acid -> Ammonia ( $NH_3$ ) -> Ornithine Cycle -> Urea.

Application: pH maintenance.

Answer: Kidneys secrete H+ ions and reabsorb $HCO_3^-$ ions to keep blood pH constant (approx 7.4).

Critical Thinking: Is urine sterile?

Answer: Yes, inside a healthy bladder, but it picks up bacteria as it exits the body.

Analysis: Micturition.

Answer: The act of passing urine. It is a reflex initiated by stretch receptors, but controllable by the brain.

Section E: Advanced Competency

Scenario: Diabetes Insipidus.

Answer: Deficiency of ADH. Different from Mellitus (Insulin deficiency/Sugar). "Insipidus" means tasteless urine.

Designing: Model.

Answer: Funnel (Capsule), Plastic tube (Nephron), Bottle (Bladder).

Application: Shivering while urinating in cold.

Answer: Emptying a warm bladder causes a sudden drop in core temperature; shivering generates heat to compensate.

Creating: Crossword.

Answer: [Terms: Cortex (Outer), Medulla (Inner), Hilum (Notch)].

Case Study: Hydronephrosis.

Answer: Back-pressure of urine causes the kidney to swell and tissue to atrophy.

JGA role.

Answer: Detects low BP and releases Renin, which leads to vasoconstriction and salt/water retention to raise BP.

Critical Thinking: Longer Loop of Henle.

Answer: Allows for greater water reabsorption, producing highly concentrated urine for water conservation.

Analysis: Cortical vs Juxtamedullary.

Answer: Cortical: Loop of Henle is short. Juxtamedullary: Loop of Henle is long and deep in medulla (for concentrating urine).

Designing: Urea concentration graph.

Answer: High in Renal Artery, significantly lower in Renal Vein.

Creating: Smart Toilet parameters.

Answer: Protein (Kidney health), Glucose (Diabetes), pH, Specific Gravity (Hydration).

Excretory System

Excretory System - Competency-Based Question Bank (with Answers)

Section A: Case-Based Questions

Section B: Assertion-Reasoning Questions

Section C: Creating and Designing (Application & Analysis)

Section D: Competency & Critical Thinking

Section E: Advanced Competency

On this page

BioBot

Excretory System

Excretory System - Competency-Based Question Bank (with Answers)

Section A: Case-Based Questions

Section B: Assertion-Reasoning Questions

Section C: Creating and Designing (Application & Analysis)

Section D: Competency & Critical Thinking

Section E: Advanced Competency

On this page