Drugs and Alcohol Abuse

NCERT grounding

NCERT Class 12 Biology, Chapter 7 (Human Health and Disease), Section 7.5 opens with the observation that the use of drugs and alcohol has been on the rise especially among the youth, and that proper education and guidance would enable youth to safeguard themselves against these dangerous behaviour patterns. The chapter then groups the commonly abused drugs into three botanical families — opioids, cannabinoids and coca alkaloids — most of which are obtained from flowering plants, with a few from fungi. The subsections that follow (7.5.1 – 7.5.4) cover adolescence, addiction and dependence, the spectrum of effects, and the five-point prevention and control framework. This subtopic page paraphrases nothing — every claim below maps back to a line in NCERT 7.5 or to the NIOS Biology supplement on lifestyle disorders.

"The drugs, which are commonly abused are opioids, cannabinoids and coca alkaloids. Majority of these are obtained from flowering plants. Some are obtained from fungi."

NCERT Class 12 Biology · Section 7.5

Drug groups, source plants and effects

NEET examiners overwhelmingly test this section as a memory grid: the drug, its source organism, its receptor or transporter, and the system it primarily affects. The four-row matrix below — opioids, cannabinoids, coca alkaloids and hallucinogens — is therefore worth memorising verbatim. Note the precise verbs NCERT uses: heroin "slows down" body function, cocaine "interferes with" dopamine transport, cannabinoids "affect the cardiovascular system". Match-the-following PYQs from 2022 and 2023 hinge on exactly these verbs.

Opioids — the depressant family

Opioids are drugs that bind specifically to opioid receptors present in the central nervous system and the gastrointestinal tract. Heroin, commonly called smack, is chemically diacetylmorphine — a white, odourless, bitter, crystalline compound. It is obtained by acetylation of morphine, which is in turn extracted from the latex of the poppy plant Papaver somniferum. The route matters for PYQs: heroin is generally taken by snorting and injection; injection routes are also the gateway to AIDS and Hepatitis-B transmission, which is why NCERT bundles the two ideas. Heroin's action is depressant: it slows down body functions. Morphine itself, although abused, is also a very effective sedative and painkiller, widely used in patients who have undergone surgery — a distinction NEET 2022 turned into a four-row match.

Cannabinoids — receptors in the brain, damage to the heart

Cannabinoids are a group of chemicals that interact with cannabinoid receptors present principally in the brain. Natural cannabinoids are obtained from the inflorescences (flower tops) of the plant Cannabis sativa. The flower tops, leaves and resin of the cannabis plant are used in various combinations to produce marijuana, hashish, charas and ganja. The intake route is inhalation and oral ingestion. The trap line in NCERT is the effect statement: cannabinoids "are known for their effects on cardiovascular system of the body." A student who answers "central nervous system" because the receptor is in the brain will lose the mark.

Coca alkaloids — dopamine and the CNS

Coca alkaloid or cocaine is obtained from the coca plant Erythroxylum coca, native to South America. Its mechanism is highly testable: cocaine interferes with the transport of the neurotransmitter dopamine. Commonly called coke or crack, it is usually snorted. It has a potent stimulating action on the central nervous system, producing a sense of euphoria and increased energy. Excessive dosage of cocaine causes hallucinations. Note the asymmetry — heroin (opioid) is a CNS depressant, cocaine (coca alkaloid) is a CNS stimulant. NEET 2018 and 2023 both exploited this.

Medicines that get misused

NCERT specifically names barbiturates, amphetamines, benzodiazepines, and similar drugs that are normally prescribed to help patients cope with mental illnesses such as depression and insomnia — but which are frequently abused when taken outside medical supervision. Morphine, while an opioid, is also a very effective sedative and painkiller used in post-surgical patients. The litmus test from the textbook: "when these are taken for a purpose other than medicinal use or in amounts/frequency that impairs one's physical, physiological or psychological functions, it constitutes drug abuse."

Tobacco and alcohol

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. The mechanism NCERT prints is mechanically simple and exam-perfect: nicotine stimulates the 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 the lung, urinary bladder and throat; bronchitis, emphysema, coronary heart disease and gastric ulcer. Tobacco chewing — the smokeless form — is associated specifically with cancer of the oral cavity.

Alcohol is the second pillar of this subtopic. NCERT does not name a single source plant for ethanol but treats it as a CNS depressant whose immediate effects include reckless behaviour, vandalism and violence. Chronic use damages the nervous system and liver, where hepatic damage manifests as cirrhosis. Use of alcohol during adolescence may also have long-term effects, often leading to heavy drinking in adulthood. The use of drugs and alcohol during pregnancy is also known to adversely affect the foetus — a one-liner NEET 2020 lifted verbatim.

Adolescence, addiction and dependence

NCERT Section 7.5.1 defines adolescence as both "a period and a process" during which a child becomes mature in attitudes and beliefs for effective participation in society. The period between 12–18 years of age may be thought of as the adolescence period — the bridge linking childhood and adulthood. Adolescence is accompanied by several biological and behavioural changes, and is therefore a very vulnerable phase of mental and psychological development.

The motivational triad NCERT lists for adolescent drug and alcohol use is curiosity, need for adventure and excitement, and experimentation. The first use is often out of curiosity, but the child then begins using these substances to escape facing problems. Stress from academic and examination pressure has played a significant role in persuading youngsters to try alcohol and drugs. The "cool / progressive" perception — promoted by television, movies, newspapers and the internet — is another driver. Other associated factors are unstable or unsupportive family structures and peer pressure.

The chapter then carefully distinguishes addiction from dependence — a definitional pair NEET has tested twice in the past five years.

Effects of drug and alcohol abuse

The immediate adverse effects are reckless behaviour, vandalism and violence. Excessive doses may lead to coma and death due to respiratory failure, heart failure or cerebral haemorrhage. Combination of drugs, or drugs taken along with alcohol, generally results in overdosing and even deaths. The common warning signs in youth are a drop in academic performance, unexplained absences, lack of interest in personal hygiene, withdrawal, isolation, depression, fatigue, aggressive and rebellious behaviour, deteriorating relationships, loss of interest in hobbies, changes in sleeping and eating habits and fluctuations in weight and appetite.

Far-reaching implications include stealing when funds run short, mental and financial distress to the family, and, for intravenous abusers, increased risk of AIDS and Hepatitis B through shared needles and syringes. Chronic abuse damages the nervous system and the liver (cirrhosis). Sportspersons sometimes misuse narcotic analgesics, anabolic steroids, diuretics and certain hormones to enhance performance — anabolic steroids in particular produce masculinisation, mood swings, depression and abnormal menstrual cycles in females, and acne, testicular atrophy, reduced sperm production, kidney and liver dysfunction, breast enlargement and premature baldness in males. In adolescents of either sex, anabolic steroid abuse can cause severe facial and body acne and premature closure of the growth centres of long bones, leading to stunted growth.

Prevention and control

NCERT 7.5.4 sets the frame with the old adage — "prevention is better than cure" — and notes that since habits like smoking, taking drugs and alcohol are most likely to begin during adolescence, identifying push-situations early is critical. Parents and teachers carry a special responsibility; parenting that combines high nurturance with consistent discipline has been associated with lowered risk of substance abuse. The textbook then prints five concrete measures, which NEET has asked as an ordered match more than once.

Worked examples

Common confusion & NEET traps