Q20. Which sequence best describes the main processes of urine formation?
[RRB Group D (17 August 2022, Shift II)]
(a) Secretion → filtration → reabsorption
(b) Filtration → reabsorption → secretion
(c) Reabsorption → filtration → storage
(d) Filtration → storage → secretion
Answer: (b) Filtration → reabsorption → secretion
Explanation: The three main renal processes are glomerular filtration, tubular reabsorption and tubular secretion. Filtration creates the initial fluid, reabsorption returns valuable substances to blood, and secretion adds selected solutes to the tubule. These processes can overlap along the nephron.
Q19. Which is the correct path followed by urine from its formation to its exit from the body?
[UPSC CDS I General Knowledge (2020)]
(a) Kidney → ureter → urinary bladder → urethra
(b) Kidney → urinary bladder → ureter → urethra
(c) Kidney → ureter → urethra → urinary bladder
(d) Urinary bladder → kidney → urethra → ureter
Answer: (a) Kidney → ureter → urinary bladder → urethra
Explanation: Urine forms in the kidneys, passes along the ureters to the bladder and leaves through the urethra during urination. The bladder stores urine temporarily. Ureters and urethra have different positions and functions and must not be interchanged.
Q18. Which tube conveys urine from each kidney into the urinary bladder?
[SSC CHSL Tier-I (17 March 2020, Shift I)]
(a) Sphincter
(b) Urethra
(c) Ureter
(d) Aorta
Answer: (c) Ureter
Explanation: Each kidney drains urine into a muscular ureter, which moves it toward the urinary bladder by peristalsis. The urethra carries urine outward from the bladder. The aorta carries blood, whereas a sphincter controls an opening.
Q17. Where is urine stored before a person urinates?
[SSC MTS (21 August 2019, Shift II)]
(a) Urinary bladder
(b) Ureter
(c) Bowman’s capsule
(d) Urethra
Answer: (a) Urinary bladder
Explanation: The urinary bladder is a distensible muscular sac that holds urine temporarily. Ureters deliver it from kidneys, while the urethra provides the exit route. Bowman’s capsule collects freshly filtered fluid within a nephron, not finished urine ready for excretion.
Q16. What type of epithelium lines much of the renal tubule?
[RRB Group D (27 November 2018, Shift I)]
(a) Simple columnar epithelium
(b) Parenchyma
(c) Simple cuboidal epithelium
(d) Stratified squamous epithelium
Answer: (c) Simple cuboidal epithelium
Explanation: Most sections of the renal tubule are lined by simple cuboidal epithelial cells specialised for transport, absorption and secretion. Their cellular structure supports the movement of water and solutes. Certain thin segments of Henle’s loop instead have squamous epithelium.
Q15. Which of the following does NOT belong to the structural parts of a nephron?
[RRB Group D (12 November 2018, Shift III)]
(a) Nissl granules
(b) Proximal convoluted tubule
(c) Distal convoluted tubule
(d) Bowman’s capsule
Answer: (a) Nissl granules
Explanation: Nissl granules are rough-endoplasmic-reticulum structures characteristic of nerve cell bodies and are involved in protein synthesis. The proximal tubule, distal tubule and Bowman’s capsule are components of the nephron, the kidney’s functional unit.
Q14. Arrange these steps of urine formation: (1) glomerular filtration, (2) tubular secretion, (3) tubular reabsorption.
[RPSC Senior Teacher Grade II Science (1 July 2017)]
(a) 1, 2, 3
(b) 1, 3, 2
(c) 2, 3, 1
(d) 3, 1, 2
Answer: (b) 1, 3, 2
Explanation: Urine formation is conventionally taught as glomerular filtration, selective tubular reabsorption and tubular secretion. Reabsorption retrieves nutrients and water, whereas secretion transfers certain wastes and ions into tubular fluid. In actual nephrons these activities can occur simultaneously in different segments.
Q13. The kidneys in humans mainly belong to which body system?
[MPPSC State Service Preliminary Examination (2017)]
(a) Digestive system
(b) Transport system
(c) Excretory system
(d) Respiratory system
Answer: (c) Excretory system
Explanation: The kidneys are principal urinary excretory organs. They remove dissolved metabolic wastes, maintain water and electrolyte balance, and help regulate blood pH and pressure. Although supplied with circulating blood, their primary classification is within the excretory system.
Q12. Nephrology is the medical branch concerned with which organ?
[RRB NTPC Stage I (6 April 2016, Shift I)]
(a) Liver
(b) Lungs
(c) Kidneys
(d) Duodenum
Answer: (c) Kidneys
Explanation: Nephrology focuses on the structure, functions and diseases of the kidneys. It covers disorders such as chronic kidney disease, glomerular inflammation and electrolyte imbalance, as well as medical management including dialysis. It is distinct from liver and lung specialties.
Q11. At which structure does ultrafiltration occur during urine formation?
[RPSC Senior Teacher Grade II Science (2015)]
(a) Bowman’s capsule and its glomerular filtration interface
(b) Proximal convoluted tubule only
(c) Distal convoluted tubule only
(d) Collecting duct only
Answer: (a) Bowman’s capsule and its glomerular filtration interface
Explanation: Ultrafiltration occurs in the renal corpuscle, where blood pressure pushes fluid across the glomerular capillary filtration barrier into Bowman’s capsule. Large proteins and blood cells normally remain in circulation. Tubular segments then modify the filtrate by reabsorption and secretion.
