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.
Last updated
Read the Homeostasis notesFree MDCAT chapter notes with key terms698 questions · page 10 of 35
- A. Ammonia
- B. Urea
- C. Ammonium
- D. Uric acid
Explanation: In humans, nitrogenous waste from protein metabolism is converted primarily into urea in the liver via the urea cycle.
Correct answer: Urea- A. No Supply of Water
- B. Sufficient Supply of Water
- C. Excess Supply of Water
- D. Restricted Supply of Water
Explanation: Excess water intake reduces reabsorption to maintain osmotic balance.
Correct answer: Excess Supply of Water- A. Cortical nephron
- B. Juxtamedullary nephron
- C. Corticomedullary nephron
- D. None of these
Explanation: Juxtamedullary nephrons have long loops that extend deep into the medulla, allowing concentration of urine in mammals.
Correct answer: Juxtamedullary nephron184. Which of the following is responsible for blood pressure regulation via renin-angiotensin system?
- A. Macula densa
- B. Juxtaglomerular cells
- C. Podocytes
- D. Collecting duct
Explanation: Juxtaglomerular cells secrete renin in response to low blood pressure, initiating the renin-angiotensin-aldosterone system.
Correct answer: Juxtaglomerular cells- A. Carbonic acid-bicarbonate
- B. Phosphate
- C. Protein buffer
- D. All of the above
Explanation: The carbonic acid-bicarbonate system maintains blood pH by neutralizing acids or bases.
Correct answer: Carbonic acid-bicarbonate- A. Hypothalamus
- B. Kidneys
- C. Liver
- D. Pancreas
Explanation: Osmoreceptors in the hypothalamus detect blood osmolarity changes and regulate ADH secretion.
Correct answer: Hypothalamus- A. Aldosterone
- B. ADH
- C. ANF
- D. Renin
Explanation: Atrial natriuretic factor (ANF) is released by the atria in response to high blood volume to reduce sodium and water retention.
Correct answer: ANF- A. Distal convoluted tubule
- B. Ascending and descending limbs of loop of Henle
- C. Collecting duct
- D. Bowman's capsule
Explanation: The counter-current multiplier system in loop of Henle concentrates urine by creating a gradient for water reabsorption.
Correct answer: Ascending and descending limbs of loop of Henle- A. Blood glucose only
- B. Blood pressure only
- C. Heart rate and ventilation rate
- D. None of the above
Explanation: During exercise, heart rate and ventilation increase to maintain oxygen and nutrient supply, ensuring homeostasis.
Correct answer: Heart rate and ventilation rate- A. Stable body temperature
- B. Uncontrolled hormone release
- C. Normal blood glucose
- D. Normal urine concentration
Explanation: Negative feedback ensures stability; failure can lead to excessive hormone secretion or homeostatic imbalance.
Correct answer: Uncontrolled hormone release- A. Liver
- B. Kidney
- C. Heart
- D. Hypothalamus
Explanation: Kidneys regulate blood volume through water and sodium reabsorption, controlling long-term blood pressure.
Correct answer: Kidney- A. Ammonia
- B. Uric acid
- C. Urea
- D. Creatinine
Explanation: Urea is the main nitrogenous waste in human, excreted in urine after protein metabolism.
Correct answer: Urea- A. Podocytes
- B. Macula densa
- C. Juxtaglomerular cells
- D. Collecting duct cells
Explanation: Macula densa cells detect sodium levels in distal tubule and signal juxtaglomerular cells to release renin.
Correct answer: Macula densa- A. A - Glomerulus
- B. E - Proximal convoluted tubule
- C. D - Loop of Henle
- D. F - Distal convoluted tubule
Explanation: The proximal convoluted tubule reabsorbs about 65-70% of water and sodium ions from the filtrate.
Correct answer: E - Proximal convoluted tubule- A. Reabsorption of water and ions
- B. Filtration of blood plasma
- C. Secretion of renin
- D. Formation of urine concentration
Explanation: Bowman's capsule filters blood plasma under pressure, initiating urine formation.
Correct answer: Filtration of blood plasma196. The figure shows a nephron with regions labeled A-D. What process occurs at the structure marked A?
- A. Selective reabsorption
- B. Active secretion
- C. Ultrafiltration under pressure
- D. Osmotic diffusion
Explanation: At the glomerulus, blood is filtered under high pressure through capillary walls into Bowman's capsule.
Correct answer: Ultrafiltration under pressure- A. Filtration of blood
- B. Active secretion of urea
- C. Maintenance of osmotic gradient
- D. Conversion of ammonia to urea
Explanation: The Loop of Henle creates an osmotic gradient to concentrate urine.
Correct answer: Maintenance of osmotic gradient- A. Cortex has loops of Henle
- B. Medulla contains glomeruli
- C. Cortex has renal corpuscles
- D. Medulla filters blood
Explanation: Cortex contains renal corpuscles (Bowman's capsule + glomerulus).
Correct answer: Cortex has renal corpuscles199. In a longitudinal section of the kidney, which one of the following is true for marked structure D?
- A. Ultrafiltration
- B. Water reabsorption through loops of Henle
- C. Glucose reabsorption
- D. Blood filtration
Explanation: Renal pyramids are in the medulla and contain loops of Henle and collecting ducts-key sites for water reabsorption.
Correct answer: Water reabsorption through loops of Henle- A. Increases K⁺ reabsorption
- B. Increases Na⁺ reabsorption and K⁺ secretion
- C. Promotes water loss
- D. Inhibits renin release
Explanation: Aldosterone from adrenal cortex enhances Na⁺ reabsorption and K⁺ secretion in distal tubules.
Correct answer: Increases Na⁺ reabsorption and K⁺ secretion