NEET 2025 MCQ with Answer Explanation : “Excretory Products and their Elimination”

Here below some basic MCQ’s of “Excretory products and their elimination” with answer which is explained in details. Let’s check one by one which is given below.

MCQ 1
Which of the following is the primary nitrogenous waste product in humans?

A) Urea
B) Uric acid
C) Ammonia
D) Creatinine

Answer: A) Urea

Explanation: In humans, the primary nitrogenous waste product is urea, which is less toxic than ammonia and is produced in the liver through the urea cycle. It is then excreted through urine.

MCQ 2
The functional unit of the kidney responsible for filtration is called:

A) Nephron
B) Glomerulus
C) Renal pelvis
D) Collecting duct

Answer: A) Nephron

Explanation: The nephron is the basic structural and functional unit of the kidney. It consists of a glomerulus for filtration and a tubule for reabsorption and secretion.

MCQ 3
Which of the following substances is primarily secreted in the proximal convoluted tubule of the nephron?

A) Urea
B) Sodium ions
C) Creatinine
D) Glucose

Answer: C) Creatinine

Explanation: While sodium ions and glucose are reabsorbed in the proximal convoluted tubule, creatinine is primarily secreted there as a waste product from muscle metabolism.

MCQ 4
Which hormone is primarily responsible for regulating water reabsorption in the kidneys?

A) Aldosterone
B) Antidiuretic hormone (ADH)
C) Atrial natriuretic peptide (ANP)
D) Renin

Answer: B) Antidiuretic hormone (ADH)

Explanation: ADH, also known as vasopressin, promotes the reabsorption of water in the collecting ducts of the kidneys, thus concentrating urine and reducing water loss.

MCQ 5
What is the main excretory organ in mammals?

A) Skin
B) Liver
C) Lungs
D) Kidneys

Answer: D) Kidneys

Explanation: The kidneys are the primary organs of excretion in mammals, responsible for filtering blood, removing waste, and balancing electrolytes and fluids.

MCQ 6
Which of the following processes in the nephron involves the movement of substances from the blood into the tubular fluid?

A) Filtration
B) Reabsorption
C) Secretion
D) Excretion

Answer: C) Secretion

Explanation: Secretion refers to the active transport of substances from the blood into the tubular fluid, allowing for the removal of additional wastes and the regulation of pH.

MCQ 7
The process by which water and solutes are reabsorbed from the nephron back into the blood is known as:

A) Filtration
B) Reabsorption
C) Secretion
D) Excretion

Answer: B) Reabsorption

Explanation: Reabsorption is the process where substances such as water, glucose, and ions are taken back from the nephron tubules into the bloodstream.

MCQ 8
Which part of the nephron is primarily responsible for the reabsorption of glucose?

A) Glomerulus
B) Loop of Henle
C) Proximal convoluted tubule
D) Distal convoluted tubule

Answer: C) Proximal convoluted tubule

Explanation: The proximal convoluted tubule reabsorbs a significant amount of glucose, amino acids, and ions back into the bloodstream.

MCQ 9
What is the role of the loop of Henle in the nephron?

A) Filtration of blood
B) Concentration of urine
C) Secretion of ions
D) Reabsorption of glucose

Answer: B) Concentration of urine

Explanation: The loop of Henle creates a concentration gradient in the medulla of the kidney, allowing for the reabsorption of water and concentrating urine.

MCQ 10
Which of the following hormones increases the reabsorption of sodium ions in the kidneys?

A) Antidiuretic hormone (ADH)
B) Aldosterone
C) Cortisol
D) Insulin

Answer: B) Aldosterone

Explanation: Aldosterone promotes sodium reabsorption in the distal convoluted tubule and collecting ducts, helping to regulate blood pressure and fluid balance.