Free Respiration MCQs with Answers

• A. tuberculosis
• B. emphysema
• C. asthma
• D. cancer

Explanation: Long-term smoking commonly causes emphysema, in which alveolar walls are destroyed, reducing respiratory surface area and impairing gas…

• A. Tuberculosis
• B. Lungs cancer
• C. Asthma
• D. Emphysema

Explanation: Tuberculosis is caused by Mycobacterium tuberculosis and spreads between people, especially through airborne droplets, so it is…

• A. 5
• B. 90
• C. 15
• D. 10

Explanation: The question uses the conventional textbook figure that more than 10 compounds in tobacco tar contribute to cancer, so option d is…

• A. 150 millions
• B. 500 millions
• C. 800 millions
• D. 1 billion

Explanation: Human lungs contain roughly 300 to 500 million alveoli, so 500 million is the closest estimate given.

• A. Thin
• B. Thick
• C. Soft
• D. Hard

Explanation: In higher animals, the skin is relatively thick and is not sufficient for rapid diffusion over the whole body, so specialised respiratory…

• A. 30%
• B. 20%
• C. 40%
• D. 50%

Explanation: Intercellular air spaces can occupy about 40% of a leaf's total volume, providing pathways for carbon dioxide and oxygen movement between…

• A. 1200
• B. 12000
• C. 100,000
• D. 1000

Explanation: Tobacco leaves may have about 100,000 stomata per square centimetre of leaf surface, allowing substantial exchange of carbon dioxide…

• A. 50
• B. 1000
• C. 5000
• D. 8000

Explanation: At ordinary temperature, water is approximately 50 times more viscous than air, so gases diffuse much more readily through air than…

• A. Air
• B. Water
• C. Soil
• D. None of these

Explanation: Air is a better respiratory medium than water because it contains a much higher concentration of oxygen and gases diffuse more rapidly…

• A. Alveoli
• B. Air sacs
• C. Bronchi
• D. Parabronchi

Explanation: Birds exchange gases across the thin walls of parabronchi, where air flows continuously through tubes surrounded by capillaries.

• A. Coetaneous
• B. Lung
• C. Pulmo-cuntaneous
• D. Through gills

Explanation: Adult frogs use both lungs and moist skin for gas exchange, but pulmonary respiration through the lungs is generally treated as the most…

• A. birds
• B. human
• C. fish
• D. frog

Explanation: Frogs use more than one respiratory surface: gases are exchanged through the skin, the lining of the buccal cavity, and the lungs.

• A. Alveoli
• B. Air sacs
• C. Parabronchi
• D. None of these

Explanation: Alveoli are the microscopic air sacs where oxygen and carbon dioxide diffuse between the air and pulmonary capillaries, making them the…

• A. Abdominal cavity
• B. Pericardial cavity
• C. Buccal cavity
• D. Thoracic cavity

Explanation: The lungs lie in the thoracic cavity, the chest cavity enclosed by the ribs and diaphragm.

• A. Erythrocytes
• B. Thrombocytes
• C. Lymphocytes
• D. Leucocytes

Explanation: Erythrocytes transport oxygen because their haemoglobin binds oxygen in the lungs and releases it in body tissues.

• A. Pleura
• B. Pericardium
• C. Peritoneum
• D. Mesothelium

Explanation: The lungs are enclosed by a double-layered membrane called the pleura, with pleural fluid between its layers to reduce friction during…

• A. Plants
• B. Motor Vehicles
• C. Bacteria
• D. None of these

Explanation: Motor vehicles produce harmful gases such as carbon monoxide, nitrogen oxides and unburned hydrocarbons through fuel combustion…

• A. 80db
• B. 30db
• C. 100db
• D. 120db

Explanation: Sound levels above about 80 dB are commonly regarded as potentially harmful with sufficient exposure and may contribute to noise…

• A. Anoxia
• B. Anorexia
• C. Hypoxia
• D. Enuresis

Explanation: Anoxia means complete absence, or near-complete absence, of oxygen supply to tissues, whereas hypoxia means reduced oxygen supply.

• A. Aphasia
• B. Dysphasia
• C. Hypoxia
• D. None

Explanation: Hypoxia means inadequate oxygen availability to body tissues; it can occur even when blood flow is adequate if oxygen delivery or cellular…