Free Effects of Smoking MCQs with Answers

1. Carbon monoxide is dangerous because it

• A. binds haemoglobin far more strongly than oxygen does and does not readily let go
• B. dissolves the walls of the alveoli
• C. destroys the red blood cells immediately
• D. prevents the diaphragm from contracting

Explanation: Carbon monoxide has roughly two hundred times the affinity of oxygen for haemoglobin and forms stable carboxyhaemoglobin, so those binding sites are taken out of use and the blood carries far less oxygen even though it looks bright red. The victim feels no shortage of breath, because breathing is driven by carbon dioxide, which is why poisoning from a gas heater can be fatal during sleep.

2. The component of cigarette smoke responsible for addiction and for raising heart rate and blood pressure is

• A. tar
• B. carbon monoxide
• C. benzene
• D. nicotine

Explanation: Nicotine reaches the brain within seconds and acts on receptors there to give the reward that makes smoking so hard to give up, while also constricting arterioles and stimulating adrenaline release. Tar is the sticky carcinogenic residue that damages the airways, and carbon monoxide reduces the oxygen carrying power of the blood. All three are harmful, but only nicotine causes the dependence.

3. Lung cancer in smokers is caused mainly by

• A. the carcinogenic chemicals in tar
• B. the heat of the smoke
• C. nicotine acting on the brain
• D. the loss of surfactant from the alveoli

Explanation: Tar contains carcinogens such as benzopyrene that mutate the genes controlling cell division in the bronchial epithelium, and years of exposure eventually produce an uncontrolled tumour. Nicotine is highly addictive but is not itself the main carcinogen, which is why a nicotine patch is far safer than a cigarette. The risk rises with the number of cigarettes and the number of years smoked.

4. In emphysema the patient becomes breathless because

• A. the trachea is blocked by mucus
• B. the walls between alveoli break down, reducing the surface area for gas exchange
• C. the diaphragm is paralysed
• D. the blood contains too few white cells

Explanation: Smoke attracts phagocytes that release elastase, which digests the elastic tissue, so alveoli merge into large air spaces with much less total surface and the lungs lose the recoil needed to breathe out. Gas exchange falls and expiration becomes an effort, so even mild exertion leaves the patient gasping. The damage is permanent, since alveolar walls cannot regenerate.

5. The persistent cough of chronic bronchitis in a smoker develops because

• A. the alveoli fill with blood
• B. the ribs lose their cartilage
• C. smoke paralyses the cilia and stimulates extra mucus, which then collects in the airways
• D. the vocal cords are permanently inflamed

Explanation: Cilia that normally sweep the mucus escalator upwards are stopped by the smoke, while the irritation makes goblet cells secrete more mucus, so it pools in the bronchi and can only be cleared by coughing. The stagnant mucus also becomes a breeding ground for bacteria, which is why chest infections are frequent. Much of this damage is reversible when a person stops smoking.

6. Passive smoking is a health hazard because

• A. the smoke changes chemically once it leaves the smoker's lungs
• B. non smokers absorb nicotine through the skin
• C. it affects only people who are already ill
• D. sidestream smoke contains the same tar, nicotine and carbon monoxide, which bystanders inhale

Explanation: Smoke drifting from the burning tip is unfiltered and carries the same carcinogens, so people sharing the room inhale them and their risk of lung cancer and heart disease rises measurably. Children exposed at home suffer more asthma attacks and chest infections, and exposure during pregnancy lowers birth weight. This evidence is what public smoking bans are based on.

7. Asthma is characterized by

• A. Emphysema
• B. Bronchoconstriction and inflammation
• C. Lung cancer
• D. Pneumonia

Explanation: Asthma involves bronchoconstriction, airway inflammation, and excess mucus production, causing wheezing and dyspnea.