Q21. Which of the following substances is primarily responsible for the formation of urine?
a) Urea
b) Glucose
c) Creatinine
d) Filtrate
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Correct Answer: d) Filtrate
Explanation: Filtrate is the fluid derived from blood plasma through the process of glomerular filtration in the kidneys. It contains water, ions, glucose, amino acids, urea, and other small molecules. Filtrate undergoes further processing in the renal tubules to form urine.
Q22. Which part of the nephron is responsible for the secretion of waste products, drugs, and excess ions into the tubular fluid?
a) Glomerulus
b) Bowman’s capsule
c) Proximal convoluted tubule
d) Distal convoluted tubule
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Correct Answer: d) Distal convoluted tubule
Explanation: The distal convoluted tubule (DCT) is the segment of the nephron responsible for the secretion of waste products, drugs, and excess ions from the peritubular capillaries into the tubular fluid. This process helps regulate the composition of urine and maintain homeostasis.
Q23. Which of the following substances is a byproduct of muscle metabolism and is excreted by the kidneys?
a) Urea
b) Bilirubin
c) Hemoglobin
d) Insulin
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Correct Answer: a) Urea
Explanation: Urea is a nitrogenous waste product formed in the liver as a result of protein metabolism. It is transported to the kidneys via the bloodstream for excretion in urine. Urea accounts for a significant portion of the nitrogenous waste eliminated from the body.
Q24. Which structure of the nephron is responsible for the initial filtration of blood to form the glomerular filtrate?
a) Glomerulus
b) Bowman’s capsule
c) Proximal convoluted tubule
d) Loop of Henle
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Correct Answer: a) Glomerulus
Explanation: The glomerulus is a network of capillaries located within Bowman’s capsule in the renal corpuscle. It is responsible for the initial filtration of blood to form the glomerular filtrate, which contains water, ions, glucose, amino acids, urea, and other small molecules.
Q25. What is the function of the juxtaglomerular apparatus (JGA) in the kidney?
a) Regulation of blood pressure
b) Regulation of blood glucose levels
c) Secretion of hormones
d) Formation of urine
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Correct Answer: a) Regulation of blood pressure
Explanation: The juxtaglomerular apparatus (JGA) is a specialized structure located near the glomerulus in the nephron. It plays a role in regulating blood pressure and kidney function by secreting renin in response to changes in blood pressure or sodium levels.
Q26. Which of the following substances is reabsorbed from the renal tubules back into the bloodstream during urine formation?
a) Urea
b) Creatinine
c) Glucose
d) Sodium ions
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Correct Answer: d) Sodium ions
Explanation: Sodium ions (Na+) are actively reabsorbed from the renal tubules back into the bloodstream during urine formation. This reabsorption occurs primarily in the proximal convoluted tubule and plays a crucial role in regulating blood volume, blood pressure, and electrolyte balance.
Q27. What is the role of the collecting duct in the kidney?
a) Filtration of blood
b) Reabsorption of water and solutes
c) Secretion of waste products
d) Concentration of urine
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Correct Answer: d) Concentration of urine
Explanation: The collecting duct is responsible for the final concentration or dilution of urine before it is excreted from the body. It reabsorbs water and solutes under the influence of antidiuretic hormone (ADH), thereby adjusting urine concentration based on the body’s hydration status.
Q28. Which of the following hormones is involved in the regulation of sodium and water balance in the body by acting on the kidneys?
a) Insulin
b) Glucagon
c) Aldosterone
d) Growth hormone
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Correct Answer: c) Aldosterone
Explanation: Aldosterone is a hormone produced by the adrenal glands that regulates sodium and water balance in the body by acting on the kidneys. It increases sodium reabsorption and potassium secretion in the distal convoluted tubule and collecting ducts, helping to maintain blood pressure and blood volume.
Q29. What is the primary function of the renal pelvis in the kidney?
a) Filtration of blood
b) Reabsorption of water
c) Storage of urine
d) Transportation of urine
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Correct Answer: d) Transportation of urine
Explanation: The renal pelvis is a funnel-shaped structure in the kidney that collects urine from the renal tubules and transports it to the ureter for excretion. It serves as a reservoir for urine before it is expelled from the body through the urinary tract.
Q30. Which of the following is a disorder characterized by the formation of kidney stones composed of crystallized minerals and salts?
a) Nephritis
b) Glomerulonephritis
c) Renal failure
d) Nephrolithiasis
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Correct Answer: d) Nephrolithiasis
Explanation: Nephrolithiasis, commonly known as kidney stones or renal calculi, is a disorder characterized by the formation of solid masses (stones) within the urinary tract. These stones are composed of crystallized minerals and salts and can cause severe pain and urinary obstruction.