Free Homeostasis MCQs with Answers
698 Homeostasis MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Homeostasis maintains a stable internal environment through the kidney and urinary system, thermoregulation and excretion. The kidney topics include filtration, selective reabsorption, urine formation and water balance, while thermoregulation involves sweating, vasodilation, vasoconstriction and hormonal control; excretion is different from egestion, which removes undigested food.
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Read the Homeostasis notesFree MDCAT chapter notes with key terms698 questions · page 8 of 35
- A. Peritubular capillaries
- B. Convoluted tubules
- C. Collecting ducts
- D. Loop of Henle
Explanation: Convoluted tubules are in renal cortex, not in pyramids.
Correct answer: Convoluted tubules- A. Create filtration slits for blood
- B. Reabsorb sodium
- C. Carry blood to renal vein
- D. Filter urea only
Explanation: Podocytes form filtration slits (pedicels) to allow plasma passage while restricting large molecules.
Correct answer: Create filtration slits for blood- A. Fats
- B. Amino acids
- C. Glucose
- D. Ketones
Explanation: Increased fatty acid oxidation produces ketone bodies, excreted in urine.
Correct answer: Ketones- A. No urine
- B. Hardly any change
- C. More concentrated urine
- D. More dilute urine
Explanation: Loop of Henle concentrates urine; without it, urine is dilute.
Correct answer: More dilute urine- A. Bowman's capsule
- B. Length of loop of Henle
- C. PCT
- D. Network of capillaries from glomerulus
Explanation: Longer loop → greater water reabsorption → concentrated urine.
Correct answer: Length of loop of Henle- A. Anuria
- B. Deamination
- C. Uremia
- D. Oliguria
Explanation: Anuria is complete absence of urine production.
Correct answer: Anuria- A. Bowman's capsule
- B. Collecting duct
- C. PCT
- D. Loop of Henle
Explanation: ADH increases water reabsorption by increasing collecting duct permeability.
Correct answer: Collecting duct- A. Increasing sodium and water excretion
- B. Activating renin
- C. Increasing aldosterone
- D. Increasing ADH
Explanation: ANF promotes natriuresis and diuresis, reducing blood pressure.
Correct answer: Increasing sodium and water excretion- A. 70% water
- B. Sodium under aldosterone control
- C. Urea
- D. Glucose
Explanation: DCT fine-tunes sodium/potassium reabsorption hormonally.
Correct answer: Sodium under aldosterone control- A. Urine pH
- B. Blood pressure & NaCl concentration
- C. Blood glucose
- D. Oxygen levels
Explanation: Macula densa senses NaCl; JG cells sense pressure to release renin.
Correct answer: Blood pressure & NaCl concentration- A. Active urea secretion
- B. Countercurrent multiplication
- C. Sodium excretion only
- D. ADH release
Explanation: Creates osmotic gradient to concentrate urine.
Correct answer: Countercurrent multiplication- A. PCT & DCT
- B. Bowman's capsule
- C. Loop of Henle & collecting ducts
- D. Glomerulus
Explanation: Medulla contains structures for water reabsorption and urine concentration.
Correct answer: Loop of Henle & collecting ducts- A. Dilute urine
- B. Concentrated urine
- C. No urine
- D. Excretion of electrolytes only
Explanation: ADH promotes water reabsorption → urine becomes concentrated.
Correct answer: Concentrated urine- A. Angiotensin I → Angiotensin II
- B. ADH
- C. ANF
- D. Aldosterone directly
Explanation: Renin converts angiotensinogen → angiotensin I, then ACE converts it to angiotensin II.
Correct answer: Angiotensin I → Angiotensin II- A. Stimulating ADH
- B. Inhibiting ADH
- C. Increasing aldosterone
- D. Increasing renin
Explanation: Less ADH → less water reabsorbed → diuresis.
Correct answer: Inhibiting ADH- A. PCT
- B. DCT
- C. Loop of Henle
- D. Bowman's capsule
Explanation: Macula densa in DCT senses NaCl concentration and regulates renin.
Correct answer: DCT- A. High protein diet
- B. Prolonged fasting or diabetes
- C. High water intake
- D. Excess sodium
Explanation: Fat breakdown produces ketones during low glucose availability.
Correct answer: Prolonged fasting or diabetes- A. Glomerular capsule
- B. Proximal convoluted tubule
- C. Loop of Henle
- D. Distal convoluted tubule
Explanation: The Loop of Henle is responsible for creating a concentration gradient in the medulla of the kidney, enabling the production of hypertonic…
Correct answer: Loop of Henle- A. Renin
- B. ADH
- C. Aldosterone
- D. ANF
Explanation: ADH controls water reabsorption in collecting ducts.
Correct answer: ADH- A. Anuria
- B. Oliguria
- C. Uremia
- D. Polyuria
Explanation: Anuria is complete cessation of urine formation due to kidney failure.
Correct answer: Anuria