MCQs on Human Health and Disease – Class 12 Biology (NCERT Based)

Course: CBSE Class 12 Biology
Unit III: Biology and Human Welfare
Topic: Human Health and Disease
Strictly as per NCERT | CBSE Board Exam Oriented | Concept-Clearing Explanations

Section A: Health, Disease and Immunity (Q1–Q15)

Q1. Health is defined by WHO as

A. absence of disease
B. physical fitness only
C. complete physical, mental and social well-being
D. proper functioning of organs

Correct Answer: C
Explanation: WHO defines health as a state of complete physical, mental and social well-being, not merely absence of disease.

Q2. Which of the following is NOT a component of health?

A. Physical well-being
B. Mental well-being
C. Social well-being
D. Genetic purity

Correct Answer: D
Explanation: Health includes physical, mental and social well-being; genetic purity is not a health component.

Q3. Communicable diseases are caused by

A. nutrient deficiency
B. pathogens
C. genetic defects
D. ageing

Correct Answer: B
Explanation: Communicable diseases spread from person to person through disease-causing agents (pathogens).

Q4. Which of the following is a bacterial disease?

A. Malaria
B. Dengue
C. Typhoid
D. AIDS

Correct Answer: C
Explanation: Typhoid is caused by Salmonella typhi, a bacterium.

Q5. Malaria is caused by

A. virus
B. bacterium
C. protozoan
D. fungus

Correct Answer: C
Explanation: Malaria is caused by Plasmodium, a protozoan parasite.

Q6. The vector for malaria is

A. Culex mosquito
B. Aedes mosquito
C. Anopheles mosquito
D. Housefly

Correct Answer: C
Explanation: Female Anopheles mosquito transmits malaria parasite.

Q7. AIDS is caused by

A. bacterium
B. fungus
C. virus
D. protozoan

Correct Answer: C
Explanation: AIDS is caused by Human Immunodeficiency Virus (HIV).

Q8. Which cells are primarily affected by HIV?

A. RBCs
B. B-lymphocytes
C. Helper T-cells
D. Macrophages only

Correct Answer: C
Explanation: HIV destroys helper T-cells (CD4), weakening immune response.

Q9. Innate immunity is

A. pathogen-specific
B. present from birth
C. acquired after infection
D. antibody-mediated

Correct Answer: B
Explanation: Innate immunity is non-specific and present since birth.

Q10. Acquired immunity is

A. non-specific
B. inherited
C. pathogen-specific
D. present at birth

Correct Answer: C
Explanation: Acquired immunity develops after exposure and is specific to pathogens.

Q11. Antibodies are produced by

A. macrophages
B. T-cells
C. plasma cells
D. neutrophils

Correct Answer: C
Explanation: Plasma cells (derived from B-cells) produce antibodies.

Q12. Which immunoglobulin is found in colostrum?

A. IgA
B. IgG
C. IgE
D. IgM

Correct Answer: A
Explanation: IgA provides passive immunity to newborns through colostrum.

Q13. Vaccination provides

A. innate immunity
B. passive immunity
C. artificial active immunity
D. natural passive immunity

Correct Answer: C
Explanation: Vaccines stimulate the body to produce antibodies actively.

Q14. Fever is a symptom of

A. injury
B. disease
C. ageing
D. malnutrition

Correct Answer: B
Explanation: Fever indicates body’s response to infection.

Q15. Which is NOT a physical barrier of innate immunity?

A. Skin
B. Mucus
C. Antibodies
D. Tears

Correct Answer: C
Explanation: Antibodies are part of acquired immunity, not innate barriers.

Section B: Common Human Diseases and Their Prevention (Q16–Q30)

Q16. Which disease is spread by contaminated water?

A. Tuberculosis
B. Cholera
C. Influenza
D. Tetanus

Correct Answer: B
Explanation: Cholera spreads through contaminated water.

Q17. The causative agent of tuberculosis is

A. virus
B. protozoan
C. bacterium
D. fungus

Correct Answer: C
Explanation: Tuberculosis is caused by Mycobacterium tuberculosis.

Q18. Which disease affects lungs mainly?

A. Typhoid
B. TB
C. Malaria
D. Amoebiasis

Correct Answer: B
Explanation: Tuberculosis primarily affects lungs.

Q19. Dengue is transmitted by

A. Anopheles
B. Culex
C. Aedes
D. Housefly

Correct Answer: C
Explanation: Aedes aegypti mosquito spreads dengue virus.

Q20. Which disease is caused by Entamoeba histolytica?

A. Typhoid
B. Amoebiasis
C. Malaria
D. Cholera

Correct Answer: B
Explanation: Amoebiasis is caused by Entamoeba histolytica.

Q21. Antibiotics are effective against

A. viruses
B. bacteria
C. protozoa only
D. all pathogens

Correct Answer: B
Explanation: Antibiotics act against bacterial infections only.

Q22. Penicillin was discovered by

A. Louis Pasteur
B. Robert Koch
C. Alexander Fleming
D. Edward Jenner

Correct Answer: C
Explanation: Alexander Fleming discovered penicillin.

Q23. Which is a sexually transmitted disease (STD)?

A. Typhoid
B. Cholera
C. Gonorrhoea
D. Malaria

Correct Answer: C
Explanation: Gonorrhoea spreads through sexual contact.

Q24. Which STD is caused by virus?

A. Syphilis
B. Gonorrhoea
C. AIDS
D. Chlamydia

Correct Answer: C
Explanation: AIDS is caused by HIV, a virus.

Q25. Use of disposable syringes helps prevent

A. malaria
B. AIDS
C. dengue
D. cholera

Correct Answer: B
Explanation: HIV spreads through contaminated needles.

Q26. Which disease causes severe dehydration?

A. TB
B. Cholera
C. Dengue
D. Typhoid

Correct Answer: B
Explanation: Cholera causes excessive loss of water and salts.

Q27. Immunity passed from mother to child is

A. active immunity
B. innate immunity
C. natural passive immunity
D. artificial immunity

Correct Answer: C
Explanation: Antibodies transferred via placenta or colostrum give passive immunity.

Q28. Which disease shows chronic fever?

A. Influenza
B. Typhoid
C. TB
D. Common cold

Correct Answer: C
Explanation: Tuberculosis causes prolonged fever.

Q29. Which disease is preventable by vaccine?

A. AIDS
B. Tuberculosis
C. Malaria
D. Cancer

Correct Answer: B
Explanation: BCG vaccine protects against TB.

Q30. Antibiotic resistance develops due to

A. overuse of antibiotics
B. vaccination
C. isolation
D. immunity

Correct Answer: A
Explanation: Excessive use selects resistant bacterial strains.

Section C: Drugs, Alcohol Abuse and Social Health (Q31–Q50)

Q31. Drugs that affect brain and behavior are called

A. antibiotics
B. hallucinogens
C. psychoactive drugs
D. analgesics

Correct Answer: C
Explanation: Psychoactive drugs alter mood, perception and behavior.

Q32. Morphine is obtained from

A. Cannabis
B. Papaver somniferum
C. Erythroxylum coca
D. Tobacco

Correct Answer: B
Explanation: Morphine is derived from opium poppy.

Q33. Heroin is also known as

A. brown sugar
B. white powder
C. LSD
D. cocaine

Correct Answer: A
Explanation: Heroin is commonly called brown sugar.

Q34. Which drug is a stimulant?

A. Morphine
B. LSD
C. Cocaine
D. Heroin

Correct Answer: C
Explanation: Cocaine stimulates central nervous system.

Q35. Excess alcohol consumption affects

A. kidneys only
B. heart only
C. liver mainly
D. lungs

Correct Answer: C
Explanation: Alcohol damages liver, causing cirrhosis.

Q36. Tobacco smoke contains

A. nicotine only
B. tar and nicotine
C. alcohol
D. morphine

Correct Answer: B
Explanation: Tar and nicotine are harmful components of tobacco smoke.

Q37. Which disease is linked with smoking?

A. Diabetes
B. Lung cancer
C. Typhoid
D. Malaria

Correct Answer: B
Explanation: Smoking increases risk of lung cancer.

Q38. Drug abuse among adolescents can be prevented by

A. punishment
B. isolation
C. education and counselling
D. medication

Correct Answer: C
Explanation: Awareness and counselling reduce drug abuse.

Q39. Steroids are misused by athletes to

A. increase immunity
B. reduce pain
C. enhance performance
D. cure diseases

Correct Answer: C
Explanation: Anabolic steroids improve muscle mass temporarily.

Q40. Which drug is a hallucinogen?

A. LSD
B. Cocaine
C. Heroin
D. Morphine

Correct Answer: A
Explanation: LSD causes hallucinations.

Q41. Withdrawal symptoms are seen in

A. vaccination
B. drug addiction
C. immunity
D. disease recovery

Correct Answer: B
Explanation: Sudden stoppage of drugs causes withdrawal symptoms.

Q42. Alcohol depresses the activity of

A. heart
B. brain
C. kidneys
D. lungs

Correct Answer: B
Explanation: Alcohol acts as a depressant on central nervous system.

Q43. Peer pressure can lead to

A. immunity
B. addiction
C. disease cure
D. vaccination

Correct Answer: B
Explanation: Peer influence is a major cause of drug abuse in youth.

Q44. Which is a social cause of disease?

A. Virus
B. Bacteria
C. Poverty
D. Protozoa

Correct Answer: C
Explanation: Poor sanitation and poverty increase disease spread.

Q45. Rehabilitation helps in

A. disease spread
B. drug abuse prevention
C. addiction recovery
D. mutation

Correct Answer: C
Explanation: Rehabilitation supports addicts in recovery.

Q46. AIDS prevention includes

A. vaccination
B. safe sex practices
C. antibiotics
D. isolation

Correct Answer: B
Explanation: Safe sex and screened blood prevent HIV transmission.

Q47. Mental health depends on

A. genes only
B. environment only
C. emotional and social balance
D. immunity

Correct Answer: C
Explanation: Mental well-being is influenced by emotional and social factors.

Q48. Smoking causes emphysema due to damage of

A. alveoli
B. bronchi
C. trachea
D. diaphragm

Correct Answer: A
Explanation: Smoking destroys alveolar walls.

Q49. Which habit increases risk of heart disease?

A. Exercise
B. Balanced diet
C. Smoking
D. Meditation

Correct Answer: C
Explanation: Smoking increases cholesterol and blood pressure.

Q50. Healthy lifestyle includes

A. drug use
B. balanced diet and exercise
C. isolation
D. stress

Correct Answer: B
Explanation: Proper diet, exercise and mental balance maintain health.