Test: Excretory System - UPSC MCQ

Urinary System

• The organs of the urinary system include the kidneys, renal pelvis, ureters, Urinary bladder and urethra.
• It is stored in the bladder and is passed out through the urinary opening at the end of a muscular tube called the urethra.
• The body takes nutrients from food and converts them to energy.
• After the body has taken the food components that it needs, waste products are left behind in the bowel and in the blood.

The correct answer is Urobilin or Urochrome.

• The yellow colour of the urine is due to the presence of pigment urochrome.

Key Points

• Normal urine colour ranges from pale yellow to deep amber 
• Pigments and other compounds in certain foods and medications can change your urine colour.

Liver

• The liver is the largest exocrine gland in the human body.
• The liver is the largest gland of the body weighing about 1.2 to 1.5 kg in an adult human.
• The exocrine glands have sweat glands, salivary glands, mammary glands, and many glands of the digestive system.
• The structure of the exocrine glands is divided into two parts:- Ductal portion and the Glandular portion.

The correct answer is Urea.

• When our cells perform their functions, certain waste products are released. These are toxic and hence need to be removed from the body.
• The process of removal of wastes produced in the cells of the living organisms is called excretion. The parts involved in excretion from the excretory system.
• Human excretory system: A mechanism to filter the blood is required and done by the blood capillaries in the kidneys. When the blood reaches the two kidneys, it contains both useful and harmful substances. The useful substances are absorbed back into the blood. The wastes dissolved in water are removed as urine.

• Aquatic animals like fishes, excrete cell waste as ammonia which directly dissolves in water.
• The major excretory product in humans is urea.

• Loop of Henle is part of Nephron.
• It is a functional and structural unit of the kidney which plays major role in Excretion. 
• Loop of Henle, long U-shaped portion of the tubule that conducts urine within each nephron of the kidney of reptiles, birds, and mammals.
• The principal function of the Loop of Henle is in the recovery of water and sodium chloride from urine.

The excretory unit in humans is Nephron.
The nephron:

• The nephron in human beings is part of the system for excretion. It is the functional unit of the mammalian kidney.
• These nephrons perform the function of filtration of blood and deposition of urine in the collecting duct.
• This urine is later excreted out from the body through the urethral opening.
• A Nephron has three main parts:
  • Proximal Nephron.
  • Loop of Henle.
  • Distal Nephron

• Urea is a waste product formed from the breakdown of proteins and is expelled from the bodies of mammals in their urine.
• In humans, the urea cycle takes place primarily in the liver and, to a lesser extent, in the kidneys.
• The liver is the principal organ of urea biosynthesis in humans.
• The process of urea production occurs in the liver as part of the urea cycle, also known as the ornithine cycle.
• This cycle converts toxic ammonia, produced from the breakdown of amino acids, into urea which is less toxic and can be easily excreted from the body.
• Urea is then transported through the bloodstream to the kidneys, where it is removed from the body in the urine.
• Thus, while the kidneys play a crucial role in excreting urea, the actual biosynthesis of urea occurs in the liver.

Explanation:

• The human excretory system includes certain organs that eliminate the wastes such as salts, carbon dioxide, urea, uric acid and water produced by the body.
• The path of the urine in the human excretory system is -

After filtering from kidney → The urine through Ureter → Stored in Urinary bladder → Exit through urethra.
Option 4 is correct

The correct answer is Kidney.

• The kidney is responsible for the purification of blood.
• The kidneys are two bean-shaped organs, each about the size of a fist.
• Kidneys are located just below the rib cage, one on each side of your spine.
• Healthy kidneys filter about a half cup of blood every minute.
• The kidney also removes waste material, extra fluid and removes it from the body in form of Urine.
• kidneys also remove acid that is produced by the cells of the body and maintain a healthy balance of water, salts, and minerals—such as sodium, calcium, phosphorus, and potassium—in the blood.
• The kidney also helps in developing hormones that control blood pressure, make red blood cells, keeps bones stronger.

• Kidneys are the excretory organs in the majority of mammals including humans
• They play a vital role in the body by performing the following functions
  • Kidneys regulate water and electrolyte balance i.e. osmoregulation.
  • Kidneys remove the metabolic waste and foreign chemicals out of the body
  • They regulate the acid-base balance in the body.
• Kidney perform these functions by the Nephrons
• A nephron is a functional and structural unit of the kidney (organ), which is involved in the process of excretion.
• It is made up of renal corpuscle or Bowman’s capsule, Glomerulus, Proximal Convoluted tubule, Loop of Henle, and Distal Convoluted Tubule.
• Bowman’s capsule is a double-walled cup-like structure in which the dense network of blood capillaries (Glomerulus) is present.
• Thus, the correct option is ''all of these functions''