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 9 of 35
- A. Nephridia
- B. Loop of Henle
- C. Nephron
- D. Pyramid
Explanation: Nephron is the microscopic structural and functional unit of the kidney, responsible for filtration, reabsorption, and secretion.
Correct answer: Nephron- A. Aldosterone
- B. Thyroxine
- C. ADH (Antidiuretic hormone)
- D. Cortisone
Explanation: Aldosterone stimulates sodium reabsorption (active uptake) in the distal tubule and indirectly influences sodium handling in the thick…
Correct answer: Aldosterone- A. The ascending limb of the loop of Henle
- B. The collecting duct
- C. The descending limb of the loop of Henle
- D. The proximal convoluted tubule
Explanation: Antidiuretic hormone (ADH) acts on the collecting duct of the nephron to increase water reabsorption, thereby regulating blood water…
Correct answer: The collecting duct- A. Ultrafiltration
- B. Reabsorption
- C. Tubular secretion
- D. All of the above
Explanation: Urine formation involves three main processes in the kidneys:Ultrafiltration (glomerular filtration) - blood is filtered in the glomerulus…
Correct answer: All of the above- A. Pituitary gland
- B. Adrenal gland
- C. Rectal gland
- D. Both pituitary and rectal gland
Explanation: Antidiuretic hormone (ADH), also known as vasopressin, is synthesized in the hypothalamus and released by the posterior pituitary gland.
Correct answer: Pituitary gland- A. Vasa recta
- B. Peritubular
- C. Lacteals
- D. Glomerulus
Explanation: The vasa recta are specialized capillaries that run parallel to the loop of Henle in the kidney's medulla, providing blood supply and…
Correct answer: Vasa recta- A. Glomerular filtration
- B. Excretion
- C. Tubular secretion
- D. Tubular reabsorption
Explanation: Tubular secretion is the process where substances are actively transported from the blood into the renal tubular fluid for excretion in…
Correct answer: Tubular secretion- A. Na+
- B. K+
- C. Mg2+
- D. Cl-
Explanation: In marine organisms, kidneys (or analogous excretory organs) help eliminate excess magnesium ions (Mg²⁺) from seawater intake to maintain…
Correct answer: Mg2+- A. Efferent arteriole
- B. Afferent arteriole
- C. Renal artery
- D. Renal vein
Explanation: The glomerulus receives blood from the afferent arteriole, which carries blood into the glomerular capillary network for filtration.
Correct answer: Afferent arteriole- A. Urinary Bladder and Urethra
- B. Ureter
- C. Adrenal Cortex
- D. Proximal Convoluted Tubule & Collecting Duct
Explanation: The majority of water and sodium ion reabsorption occurs in the proximal convoluted tubule (PCT) of the nephron.
Correct answer: Proximal Convoluted Tubule & Collecting Duct- A. Creatine
- B. Amino acids
- C. Carbon dioxide
- D. Ammonia
Explanation: The urea cycle is a metabolic pathway that converts toxic ammonia (NH₃), produced from the breakdown of amino acids, into urea, which is…
Correct answer: Ammonia- A. Kidney
- B. Cortex
- C. Medulla
- D. Loop of Henle
Explanation: The loop of Henle functions as a countercurrent multiplier in the kidney's nephron.
Correct answer: Loop of Henle- A. Cortical nephrons
- B. Proximal Convoluted Tubule
- C. Juxtamedullary nephrons
- D. The tissue of cortex
Explanation: Juxtamedullary nephrons have long loops of Henle that extend deep into the medulla, enabling them to create a strong osmotic gradient for…
Correct answer: Juxtamedullary nephrons- A. Efferent Arteriole
- B. Collecting Tubules
- C. Peritubular capillaries
- D. Proximal tubules
Explanation: After filtration, the filtrate moves through the proximal tubule, loop of Henle, and then the distal convoluted tubule.
Correct answer: Collecting Tubules- A. Na+ ions
- B. K+ ions
- C. Cl- ions
- D. Water
Explanation: The ascending limb of the loop of Henle is impermeable to water, so water cannot pass through it.
Correct answer: Water- A. Juxtamedullary nephrons
- B. Cortical nephrons
- C. Proximal tubule
- D. Distal tubule
Explanation: Juxtamedullary nephrons have long loops of Henle that extend deep into the medulla, enabling the countercurrent multiplier system which…
Correct answer: Juxtamedullary nephrons- A. Distal tubule
- B. Proximal tubule
- C. Ascending limb
- D. Descending limb
Explanation: The proximal convoluted tubule (PCT) is the site where ~65- 80% of filtered water, electrolytes, glucose, and amino acids are reabsorbed…
Correct answer: Proximal tubule- A. Urea in tadpole, ammonia in adult frog
- B. Ammonia in tadpole, urea in adult frog
- C. Urea in both tadpole and adult frog
- D. Urea in tadpole, uric acid in adult frog
Explanation: Aquatic tadpoles excrete ammonia; terrestrial adults conserve water via urea excretion.
Correct answer: Ammonia in tadpole, urea in adult frog- A. Loop of Henle
- B. Collecting Duct
- C. Bowman's Capsule
- D. Glomerulus
Explanation: The counter‑current multiplier system operates in the loop of Henle, where the opposing flow of fluid in the descending and ascending…
Correct answer: Loop of Henle- A. Mg
- B. ADH
- C. Kidney stones
- D. High pH
Explanation: Antidiuretic hormone (ADH), also called vasopressin, acts on the collecting ducts of the nephron to increase water permeability, leading…
Correct answer: ADH