SSC CHSL 2025 PYQ — Question 98

The correct answer is Option 1: By fine hairs in the nose.
Explanation:
In the human respiratory system, when air enters the body through the nose, nature has created a remarkable filtration system to clean and purify it.
Fine Hairs (Cilia): The fine hairs present in the nasal passages serve to trap dust particles, dirt, and other foreign microorganisms floating in the air.
Mucus: Inside the nose, there is a sticky substance known as 'mucus.' It traps the particles caught by the hairs and prevents them from reaching the lungs.
Temperature Regulation: The nasal passages also function to condition the air to match body temperature (warming or cooling it) and to add moisture to it.
Analysis of Other Options:

• Tonsils (Option 2): These are lymphoid tissues located at the back of the throat that help fight infections; however, their primary function is not to filter the air.
• Cartilage Rings (Option 3): The trachea (windpipe) contains C-shaped rings of cartilage that prevent the windpipe from collapsing, thereby ensuring the airway remains open.
• Lungs (Option 4): The primary function of the lungs is to facilitate the exchange of oxygen and carbon dioxide (gas exchange) between the blood and the air.

Additional Facts:

• Alveoli: These are tiny, grape-like structures located inside the lungs where the actual gas exchange takes place.
• Diaphragm: This is a muscle situated beneath the lungs that plays a pivotal role in the process of breathing in and out. The Effects of Smoking: Smoking destroys the tiny hair-like structures (cilia) found in the nose and windpipe, thereby increasing the risk of dirt and debris entering the lungs.

Potential Questions for Upcoming Exams:

Question: What prevents the windpipe (trachea) from collapsing in the human body?
Answer: Cartilaginous rings.
Question: What is considered the functional unit of the lungs?
Answer: Alveoli.
Question: What changes occur in the intercostal muscles (muscles between the ribs) and the diaphragm during inhalation?
Answer: The diaphragm moves downward (flattens), and the ribs move upward and outward.