CBSE Class 12-science Answered

(i)Tobacco in any form is injurious to health because-

(a) Smoking of tobacco is associated with cancers of lung, urinary bladder, coronary heart disease, gastric ulcer etc.

(b) Smoking increases carbon monoxide content in blood and reduces the concentration of haem-bound oxygen, causing oxygen-deficiency in the body.

(c) Oral cancer is due to chewing of tobacco etc.

(d) Nicotine, the main content of tobacco stimulates adrenal gland to release adrenaline and nor-adrenaline into blood which raises the blood pressure and increases heart beat.

(ii) Hallucinogens are a class of psychedelic drugs which affect cerebrum and sense organs to alter thought, feeling and perception. Two examples are lysergic acid diethyl amides (LSD) and methylenedioxy methamphetamine (MDMA). Clinically, they are used to treat depression and insomnia.