SMOKING

(a) Cancer and heart disease are two major causes of death.
Explain how the following may contribute towards these diseases:
(i) Smoking cigarettes [4]
(ii)Eating an unbalanced diet [2]

(b)(i) Why is smoking now widely regarded as a socially unacceptable habit? [1]
(ii) What does ‘passive smoker’ refer to? [1]

ANSWERS
(a)(i) Cigarette smoke contains more than 4000 chemicals, some of which are harmful to the body.
Tar is one of the harmful chemicals causing lung cancer [1/2]
•It accumulates in the lungs during smokingand contains many cancer-causing (carcinogenic) chemicals [1/2]
•It can induce the normal cells to divide at an abnormal rate, resulting in growths (cancer)[1/2]
•These block the alveoli/airways, reducing the efficiency for gaseous exchange [1/2]

•Smoking cigarettes causes heart disease: The combined effect of nicotine and carbon monoxide damage endothelium, increasing possibility of plaque formation [1/2]
•Nicotine increases levels of lipids in the blood, increasing possibility of plaque formation [1/2]
•Nicotine also causes vasoconstriction of arteries, and this means less blood flows to cardiac muscle due to the atherosclerosis of the coronary arteries;

(ii) Eating of food containing too much animal fats, hence increasing the tendency for saturated fats and cholesterol to get deposited under the endothelium of the arteries, forming plaques [1/2]
•This condition, atherosclerosis, will affect the coronary arteries, resulting in less blood flowing to cardiac muscles [1/2]
•An unbalanced diet may also lead to obesity which increases the risk of developing coronary heart disease [1/2]
•Eating an unbalanced diet lacking in dietary fibre may increase the risk of developing colon cancer [1/2]

(b)(i) Smoking is now regarded as an unacceptable social habit because the cigarette smoke emitted by the smoker would cause harm to others if inhaled by the people around him;

(ii) It refers to people who involuntarily breathe in smoke that is produced by others who are smoking;