Biology MCQ for MBBS Entrance Exam

Here are Class 12 Biology Multiple Choice Questions and Answers with detailed explanations for MBBS Entrance Exam.

1. Cocaine is obtained from __________
a) Erythroxylum coca
b) Papaver somniferum
c) Datura
d) Atropa belladonna
View Answer

Answer: a
Explanation: Cocaine is a local anaesthetic, vasoconstrictor and powerful stimulant which is obtained from the dried leaves of Coca plant, Erythroxylum coca which is native to South America. Its leaves can be chewed, eaten, sniffed in powdered form or taken as a drink.

2. Which of the following symptoms does not occur by the intake of small quantities of cocaine?
a) Increases hunger
b) Increases Mental alertness
c) Relaxes fatigued muscles
d) Reduces hunger
View Answer

Answer: d
Explanation: In small quantities, as present in the leaves, cocaine relaxes fatigued muscles, increases mental alertness and physical strength but it reduces hunger. Its purified content was once used as a local anaesthetic, especially in dentistry.

3. Which of the following is a powdered form of cocaine?
a) Crack
b) Speedball
c) Coke
d) Betelnut
View Answer

Answer: c
Explanation: Powdered cocaine is coke. The drug is a bitter, white, crystalline powder which is often adulterated with glucose or lactose and local anaesthetics. It is inhaled or injected.

4. Cocaine suppresses the brain activity and produces a feeling of calmness, relaxation and drowsiness.
a) True
b) False
View Answer

Answer: b
Explanation: Cocaine has a potent stimulating action on the central nervous system producing a sense of euphoria and increased energy. Cocaine gives a feeling of pleasure followed by hallucinations.

5. Which of the following is not a physiological symptom associated with the intake of cocaine?
a) Increase in heartbeat
b) Increase in blood pressure
c) A decrease in body temperature
d) Increase in body temperature
View Answer

Answer: c
Explanation: Cocaine increases heartbeat, blood pressure and body temperature. In high dose, the rise in temperature or blood pressure may be lethal. The drug alters membrane transport, prevents uptake of catecholamines at adrenergic nerve endings and interferes with the transport of dopamine.

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6. Which of the following coca alkaloids is present in an endosperm?
a) Crack
b) Speedball
c) Coke
d) Betelnut
View Answer

Answer: d
Explanation: The betelnut is the seed of Areca catechu. The endosperm or kernel contains a number of alkaloids, the major being arecoline. It is mildly stimulant and vermifuge.

7. Cocaine is a non- toxic drug and enhances the physiological functions of our body.
a) False
b) True
View Answer

Answer: a
Explanation: Cocaine is a toxic drug and deteriorates the health of a person who is addicted to it. Cocaine is toxic to the brain, produces severe headache, convulsions, loss of appetite and causes insomnia. Cardiac arrhythmia and respiratory depression are also common.

8. Which of the following statement is false regarding hallucinogens?
a) These drugs are also known as psychedelics
b) They produce a true sensory stimulus
c) They cause Intensified sensory perceptions
d) They are also responsible for Perceptual Distortion
View Answer

Answer: b
Explanation: Hallucinogens are formulations which changes one’s perceptions, thoughts and feelings without any true sensory stimulus. They are also called psychedelics. These drugs are characterised by intensified sensory perception, perceptual distortion, hallucination and intense feeling of either despair or euphoria.

9. Which of the following plant is depicted in the diagram given below?

a) Datura
b) Atropa belladonna
c) Opium poppy
d) Cannabis sativa
View Answer

Answer: a
Explanation: The given diagram shows the flowering branch of the Datura plant. It is a well-known plant with hallucinogenic properties. The drugs obtained from this plant changes one’s thoughts and feelings without actually sending any true sensory stimulus.

10. What is the full form of LSD?
a) Lanthanide stimulated drug
b) Lysergic acid diethylamide
c) Lanthanide steric drug
d) Lysergic drug
View Answer

Answer: b
Explanation: LSD stands for Lysergic acid diethylamide. LSD leads to CNS damage, non-coordination of body parts, chromosomal aberrations, foetal abnormalities and psychosis. It may lead to unconsciousness and even death.

11. LSD is extracted from which of the following organism?
a) A fungus
b) A plant
c) An animal
d) A bacterium
View Answer

Answer: a
Explanation: LSD is a crystalline amidated alkaloid derived from ergot, an extract got from the fruiting body of fungus Claviceps purpurea. LSD was found to be psychedelic in 1947. There is marked hallucinations, ecstasy and emotional outburst.

12. Which of the following is not a physiological effect observed by the intake of LSD?
a) High blood pressure
b) Rapid heartbeat
c) Pupillary dilation
d) Reduced heart rate
View Answer

Answer: d
Explanation: Psychological and physiological effects are found even in a small dose of only 20 μg taken orally. The drug brings about rapid heartbeat, high blood pressure, high body temperature, pupillary dilation, vomiting, tremors. There are mood changes, visual illusions, conflicting often bizarre perceptual changes.

More Biology MCQs for MBBS Entrance Exam:

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