Excretory System — Set 1
Biology · उत्सर्जन तंत्र · Questions 1–10 of 50
What is the primary structural and functional unit of the human kidney?
Correct Answer: B. Nephron
The nephron is the basic functional unit responsible for filtering blood and forming urine. Each human kidney contains approximately one million of these microscopic structures. They consist of a renal corpuscle and a renal tubule.
Which nitrogenous waste is primarily excreted by humans?
Correct Answer: A. Urea
Humans are ureotelic organisms that primarily excrete urea as a metabolic byproduct. Urea is produced in the liver through the ornithine cycle to reduce toxicity. It is much less toxic than ammonia and requires less water for excretion.
The cup-shaped structure at the beginning of a nephron is called the?
Correct Answer: D. Bowman's capsule
Bowman's capsule surrounds the glomerulus and collects the initial filtrate from the blood. This structure performs the first step in the filtration of blood to form urine. It was named after the English surgeon and anatomist William Bowman.
Which organ in the human body is responsible for the synthesis of urea?
Correct Answer: B. Liver
The liver converts highly toxic ammonia into less toxic urea via the urea cycle. Once synthesized, urea is released into the bloodstream and later filtered out by the kidneys. This process is essential for nitrogen balance in the body.
What is the name of the tube that carries urine from the kidney to the urinary bladder?
Correct Answer: C. Ureter
The ureter is a muscular tube that uses peristaltic movements to transport urine. Each kidney has one ureter that connects it to the bladder. It prevents the backflow of urine through a functional valve-like mechanism.
The process of maintaining a constant osmotic pressure in the body fluids is known as?
Correct Answer: C. Osmoregulation
Osmoregulation is the active regulation of the osmotic pressure of an organism's body fluids. It ensures that the concentration of water and salts remains within physiological limits. The kidneys play a central role in this homeostatic process.
Which hormone regulates the reabsorption of water in the distal convoluted tubule and collecting duct?
Correct Answer: B. Antidiuretic Hormone
Antidiuretic Hormone (ADH), or vasopressin, increases water permeability in the kidney tubules. It is released by the posterior pituitary gland when the body is dehydrated. A deficiency of this hormone can lead to a condition called diabetes insipidus.
The indentation on the medial side of the kidney through which the ureter and blood vessels enter is the?
Correct Answer: B. Hilum
The hilum is the entry and exit point for the renal artery, renal vein, and ureter. It gives the kidney its characteristic bean-like shape. Internally, the hilum leads to a space called the renal sinus.
Which part of the nephron is most responsible for the concentration of urine?
Correct Answer: C. Loop of Henle
The Loop of Henle creates a concentration gradient in the renal medulla using a counter-current mechanism. This allow for the efficient reabsorption of water from the filtrate. Long loops of Henle are typical in desert animals to conserve water.
What is the typical pH value of human urine under normal conditions?
Correct Answer: A. 6.0
Human urine is generally slightly acidic with an average pH of around 6.0. However, the pH can vary from 4.5 to 8.0 depending on diet and health status. High protein diets tend to make urine more acidic.