Homeostasis

Homeostasis MDCAT MCQs with answers

63 past paper MCQs from Biology unit 15, Homeostasis, across 3 topics. They are arranged topic by topic; bigger topics show a sample here and link to their full set and to study notes. Tap “Show answer” for the correct option and a short solution.

Practise as a quiz

Homeostasis and the Kidney

1.Kidneys perform their osmoregulatory role under the effect of Antidiuretic Hormone, which type of urine is produced in this situation? (UHS MDCAT 2025)

  1. Hypotonic urine with decreased volume
  2. Hypotonic urine with increased volume
  3. Hypertonic urine with decreased volume
  4. Hypertonic urine with increased volume
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Correct answer: (c) Hypertonic urine with decreased volume

ADH makes the collecting ducts reabsorb more water, so a smaller volume of concentrated, hypertonic urine leaves.

2.The process of osmoregulation refers to: (UHS MDCAT 2025)

  1. The filtration of blood to remove metabolic waste
  2. The regulation of solute and water movement between an organism and its environment
  3. The creation of an osmotic gradient in the kidney medulla
  4. The secretion of hormones that control blood plasma
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Correct answer: (b) The regulation of solute and water movement between an organism and its environment

Osmoregulation is the control of the water and solute balance between the organism and its surroundings.

3.Which type of nephron is responsible for the development of osmotic gradients in the renal medulla? (KMU MDCAT 2025)

  1. Glomerular
  2. Cortical
  3. Juxtamedullary
  4. Medullary
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Correct answer: (c) Juxtamedullary

Only the juxtamedullary nephrons have loops long enough to build the osmotic gradient of the medulla.

All 40 Homeostasis and the Kidney MCQs → Homeostasis and the Kidney notes →

Thermoregulation

4.A person in hot weather is unable to maintain body temperature. Which physiological process has failed? (UHS MDCAT 2025)

  1. Vasodilation & sweating
  2. Vasoconstriction
  3. Shivering
  4. Renin secretion
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Correct answer: (a) Vasodilation & sweating

Cooling in the heat depends on widening the skin arterioles and on sweating.

5.In a heat stroke the hypothalamus will detect an increase in core body temperature, which of the following response is triggered (KMU MDCAT 2025)

  1. Vasoconstriction and shivering
  2. Vasodilation and sweating
  3. Increased metabolic rate
  4. Release of thyroxin
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Correct answer: (b) Vasodilation and sweating

The hypothalamus answers overheating by widening the skin vessels and turning on the sweat glands.

6.Shivering thermogenesis involves: (SIBA MDCAT 2025)

  1. Voluntary muscle contraction
  2. Involuntary muscle contraction.
  3. Dehydration
  4. Hormone secretion
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Correct answer: (b) Involuntary muscle contraction.

Shivering is a rapid involuntary contraction of skeletal muscle whose only product is heat.

All 9 Thermoregulation MCQs → Thermoregulation notes →

Excretion

7.Which of the following organisms eliminate nitrogenous waste mainly in the form of uric acid? (UHS MDCAT 2025)

  1. Freshwater Fish
  2. Amphibians
  3. Birds
  4. Mammals
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Correct answer: (c) Birds

Birds and reptiles are uricotelic, which saves the water an egg cannot spare.

8.Which nitrogenous waste has the lowest solubility in water? (KMU MDCAT 2025)

  1. Urea
  2. Ammonia
  3. Uric acid
  4. Nitrite
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Correct answer: (c) Uric acid

Uric acid is almost insoluble, which is why it can be excreted as a paste with almost no water.

9.By nature, human excretory system is: (KMU MDCAT 2025)

  1. Ammonotelic
  2. Uricotelic
  3. Ureotelic
  4. Aminotelic
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Correct answer: (c) Ureotelic

Humans convert their ammonia to urea in the liver, so they are ureotelic.

All 14 Excretion MCQs → Excretion notes →

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