Read the passage and answer the following question:
Smoking also paves the way to hard drugs. Tobacco has been used by human beings for more than 400 years. It is smoked, chewed or used as a snuff. Tobacco contains a large number of chemical substances including nicotine, an alkaloid. Nicotine stimulates adrenal gland to release adrenaline and nor-adrenaline into blood circulation, both of which raise blood pressure and increase heart rate. Smoking is associated with increased incidence of cancers of lung, urinary bladder and throat, bronchitis, emphysema, coronary heart disease, gastric ulcer, etc. Tobacco chewing is associated with increased risk of cancer of the oral cavity. Smoking increases carbon monoxide (CO) content in blood and reduces the concentration of haem-bound oxygen. This causes oxygen deficiency in the body. Knowing the dangers of smoking and chewing tobacco, and its addictive nature, the youth and old need to avoid these habits. Any addict requires counselling and medical help to get rid of the habit.
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Smoking causes oxygen deficiency in the body.
Reason (R): Nicotine stimulates the adrenal gland to release adrenaline and nor-adrenaline into blood circulation, both of which raise blood pressure and increase heart rate.
In the light of the above statements, choose the most appropriate answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Both (A) and (R) are true but (R) is not the correct explanation of (A).
The passage gives two separate effects of smoking. One is on the heart and blood pressure, through nicotine and the hormones of the adrenal gland. The other is on the oxygen carried by the blood, through carbon monoxide.
Assertion (A): Smoking causes oxygen deficiency in the body. — True. The passage states that smoking increases the carbon monoxide (CO) content in blood and reduces the concentration of haem-bound oxygen, and that “This causes oxygen deficiency in the body.”
Reason (R): Nicotine stimulates the adrenal gland to release adrenaline and nor-adrenaline into blood circulation, both of which raise blood pressure and increase heart rate. — True. The passage states this in almost the same words. Nicotine is the alkaloid present in tobacco.
Why R does not explain A? R tells us how smoking raises the blood pressure and heart rate. It says nothing about oxygen. The oxygen deficiency comes from the extra CO in the blood, which leaves less oxygen bound to haem. Both statements are true, but R is not the reason for A.