Question

Match List I with List II \[ \renewcommand{\arraystretch}{1.5} \begin{array}{|c|l|c|l|} \hline \multicolumn{2}{|c|}{List I & \multicolumn{2}{c|}{List II \hline (a) & \text{Mucus lining} & (I) & \text{Physiological barrier} \hline (b) & \text{Acid in stomach} & (II) & \text{Cellular barrier} \hline (c) & \text{PMNL-neutrophils} & (III) & \text{Physical barrier} \hline (d) & \text{Interferons} & (IV) & \text{Cytokine barrier} \hline \end{array} \] Choose the correct answer from the options given below:

• A. a-II, b-I, c-IV, d-III
• B. a-III, b-II, c-IV, d-I
• C. a-II, b-III, c-I, d-IV
• D. a-III, b-I, c-II, d-IV

Hint:

Innate immunity consists of four major barriers: \[ \text{Physical barrier} \rightarrow \text{Skin, mucus lining} \] \[ \text{Physiological barrier} \rightarrow \text{Stomach acid, saliva} \] \[ \text{Cellular barrier} \rightarrow \text{Neutrophils, macrophages} \] \[ \text{Cytokine barrier} \rightarrow \text{Interferons} \]

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The human immune system guards the body against foreign pathogens using a multi-tiered defense strategy called Innate Immunity. Innate immunity is non-specific, meaning it protects against all invaders uniformly from birth. It consists of four distinct operational defensive barriers: physical, physiological, cellular, and cytokine barriers. Together, they block entry, kill penetrating microbes, and sound the alarm for systemic backup.
Step 2: Detailed Explanation:
Let's analyze and categorize each component of the human innate immune system: - (a) Mucus lining: This acts as a structural roadblock. The mucus coatings of the respiratory, gastrointestinal, and urogenital tracts physically trap microbes, preventing them from penetrating deeper tissues. Therefore, it is a Physical barrier (III). - (b) Acid in stomach: This acts as a chemical environment defense. The highly acidic gastric juices ($\text{HCl}$), along with saliva in the mouth and tears from the eyes, create an unfriendly environment that kills ingested pathogens. Therefore, it is a Physiological barrier (I). - (c) PMNL-neutrophils: Polymorphonuclear Leukocytes (PMNL-neutrophils) along with monocytes and macrophages are specialized white blood cells that patrol the body, engulfing and destroying invading microbes via phagocytosis. Therefore, they form a Cellular barrier (II). - (d) Interferons: These are specialized defensive signaling proteins secreted by virus-infected cells. They diffuse to neighboring uninfected cells, stimulating them to produce antiviral proteins to prevent the virus from replicating further. Therefore, they represent a Cytokine barrier (IV). Combining these pairings gives the correct sequence: a-III, b-I, c-II, d-IV. This matches option (D).
Step 3: Final Answer:
The correct matching sequence is a-III, b-I, c-II, d-IV.