CBSE Class 12 Biology MCQs with Answers & Explanations (NCERT): Human Health and Disease

Course & Examination Details

• Course: CBSE Class 12 Biology
• Unit: Unit III – Biology and Human Welfare
• Chapter: Chapter 8 – Human Health and Disease
• Prescribed Textbook: NCERT Biology Class XII
• Examination: CBSE Class 12 Board Examination
• Question Type: Multiple Choice Questions (MCQs)
• Coverage: Conceptual, application-based, competency-oriented (NCERT aligned)

Section A: Health and Its Significance

Q1. Health is best defined as:

A. Absence of disease
B. Physical fitness only
C. Mental well-being only
D. Complete physical, mental and social well-being

Correct Answer: D
Explanation: According to WHO, health includes physical, mental, and social well-being, not merely absence of disease.

Q2. Which factor does NOT directly affect human health?

A. Genetic makeup
B. Sanitation
C. Nutrition
D. Eye colour

Correct Answer: D
Explanation: Eye colour does not influence health status, whereas genetics, hygiene, and nutrition do.

Q3. Health is considered a social issue because it depends on:

A. Individual immunity only
B. Medical treatment only
C. Sanitation and public awareness
D. Personal habits alone

Correct Answer: C
Explanation: Social factors like sanitation, education, and public healthcare strongly influence health.

Q4. Congenital diseases are those which:

A. Spread through infection
B. Develop due to lifestyle
C. Are present at birth
D. Are caused by pathogens

Correct Answer: C
Explanation: Congenital diseases are present from birth, often due to genetic defects.

Q5. Which one is a non-infectious disease?

A. Typhoid
B. Pneumonia
C. Malaria
D. Diabetes

Correct Answer: D
Explanation: Diabetes is a metabolic disorder and does not spread from person to person.

Section B: Common Human Diseases

Q6. Typhoid is caused by:

A. Virus
B. Protozoan
C. Bacterium
D. Fungus

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

Q7. Pneumonia primarily affects the:

A. Liver
B. Alveoli of lungs
C. Kidney
D. Brain

Correct Answer: B
Explanation: Pneumonia causes inflammation of alveoli, reducing oxygen exchange.

Q8. Malaria is transmitted by:

A. Housefly
B. Female Anopheles mosquito
C. Aedes mosquito
D. Tsetse fly

Correct Answer: B
Explanation: Female Anopheles mosquito transmits Plasmodium.

Q9. Amoebiasis spreads mainly through:

A. Air
B. Vector bite
C. Contaminated food and water
D. Physical contact

Correct Answer: C
Explanation: Entamoeba histolytica spreads via contaminated food and water.

Q10. Which disease is caused by a protozoan parasite?

A. Typhoid
B. Pneumonia
C. Malaria
D. Tuberculosis

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

Section C: Pathogens and Parasites

Q11. Pathogens are:

A. Useful microorganisms
B. Disease-causing organisms
C. Free-living organisms
D. Non-living agents

Correct Answer: B
Explanation: Pathogens cause diseases in hosts.

Q12. Which pathogen is an obligate intracellular parasite?

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

Correct Answer: C
Explanation: Viruses require host cells for replication.

Q13. A parasite that lives inside the host body is called:

A. Ectoparasite
B. Endoparasite
C. Vector
D. Saprophyte

Correct Answer: B
Explanation: Endoparasites live within the host body.

Q14. Which organism causes ascariasis?

A. Virus
B. Bacterium
C. Protozoan
D. Helminth

Correct Answer: D
Explanation: Ascariasis is caused by the helminth Ascaris lumbricoides.

Q15. Lice are classified as:

A. Endoparasites
B. Pathogens
C. Ectoparasites
D. Vectors

Correct Answer: C
Explanation: Lice live on the body surface and are ectoparasites.

Section D: Immunity

Q16. Immunity refers to:

A. Ability to digest food
B. Resistance to disease
C. Body temperature regulation
D. Hormonal control

Correct Answer: B
Explanation: Immunity is the body’s defence against pathogens.

Q17. Innate immunity is characterised by:

A. Specificity and memory
B. Long-term protection
C. Non-specific immediate response
D. Antibody production only

Correct Answer: C
Explanation: Innate immunity is non-specific and acts immediately.

Q18. Which of the following is a physical barrier of innate immunity?

A. Antibodies
B. Skin
C. Lymphocytes
D. Interferons

Correct Answer: B
Explanation: Skin prevents pathogen entry.

Q19. Acquired immunity shows memory due to:

A. Phagocytes
B. Platelets
C. Lymphocytes
D. Red blood cells

Correct Answer: C
Explanation: Memory cells are formed by lymphocytes.

Q20. Which cells produce antibodies?

A. T-cells
B. Macrophages
C. B-cells
D. Neutrophils

Correct Answer: C
Explanation: B-lymphocytes produce antibodies.

Section E: Vaccination

Q21. Vaccination provides:

A. Natural passive immunity
B. Artificial active immunity
C. Natural active immunity
D. Artificial passive immunity

Correct Answer: B
Explanation: Vaccination stimulates antibody production by the body.

Q22. Which vaccine is a recombinant vaccine?

A. BCG
B. Polio
C. Hepatitis B
D. Typhoid

Correct Answer: C
Explanation: Hepatitis B vaccine is produced using genetic engineering.

Q23. Herd immunity refers to:

A. Individual resistance
B. Natural immunity
C. Community-level protection
D. Passive immunity

Correct Answer: C
Explanation: High immunity in population reduces disease spread.

Q24. Vaccines work by stimulating formation of:

A. Pathogens
B. Antigens only
C. Antibodies and memory cells
D. Phagocytes only

Correct Answer: C
Explanation: Memory cells provide long-term protection.

Q25. Which immunity is short-lived?

A. Active immunity
B. Passive immunity
C. Acquired immunity
D. Artificial immunity

Correct Answer: B
Explanation: Passive immunity lacks memory cells.

Section F: Allergies

Q26. Allergy is caused due to:

A. Weak immunity
B. Autoimmunity
C. Hypersensitive immune response
D. Infection

Correct Answer: C
Explanation: Allergy is an exaggerated immune response.

Q27. Which antibody is involved in allergic reactions?

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

Correct Answer: D
Explanation: IgE mediates allergy.

Q28. Histamine is released from:

A. RBCs
B. Neurons
C. Mast cells
D. Platelets

Correct Answer: C
Explanation: Mast cells release histamine during allergy.

Q29. Common allergens include:

A. Viruses
B. Bacteria
C. Pollen
D. Antibiotics

Correct Answer: C
Explanation: Pollen commonly triggers allergies.

Q30. Allergy symptoms include:

A. Fever only
B. Sneezing and rashes
C. Anaemia
D. Paralysis

Correct Answer: B
Explanation: Sneezing, watery eyes, and rashes are common symptoms.

Section G: Autoimmune Diseases

Q31. Autoimmune diseases occur due to:

A. Weak immune system
B. Attack on self-antigens
C. Infection by bacteria
D. Allergic response

Correct Answer: B
Explanation: Immune system mistakenly attacks own tissues.

Q32. Which is an autoimmune disease?

A. Typhoid
B. Malaria
C. Rheumatoid arthritis
D. Tuberculosis

Correct Answer: C
Explanation: Rheumatoid arthritis is autoimmune.

Q33. Type 1 diabetes occurs due to:

A. Excess insulin
B. Lack of insulin production
C. Insulin resistance
D. Viral infection only

Correct Answer: B
Explanation: Immune destruction of pancreatic cells reduces insulin.

Section H: Drugs and Alcohol Abuse

Q34. Drugs affect mainly the:

A. Digestive system
B. Respiratory system
C. Nervous system
D. Circulatory system

Correct Answer: C
Explanation: Drugs alter brain function and behaviour.

Q35. Alcohol is classified as a:

A. Stimulant
B. Hallucinogen
C. Depressant
D. Narcotic

Correct Answer: C
Explanation: Alcohol depresses central nervous system.

Q36. One harmful effect of alcohol abuse is:

A. Improved reflexes
B. Liver cirrhosis
C. Increased immunity
D. Better coordination

Correct Answer: B
Explanation: Chronic alcohol damages liver.

Q37. Drug addiction refers to:

A. Occasional use
B. Controlled intake
C. Physical and psychological dependence
D. Medical treatment

Correct Answer: C
Explanation: Addiction causes dependence on drugs.

Q38. Sharing needles can transmit:

A. Malaria
B. Typhoid
C. HIV
D. Pneumonia

Correct Answer: C
Explanation: HIV spreads through contaminated syringes.

Section I: Prevention and Control

Q39. Which measure helps prevent infectious diseases?

A. Poor hygiene
B. Vaccination
C. Drug abuse
D. Malnutrition

Correct Answer: B
Explanation: Vaccination prevents infections.

Q40. Balanced diet helps in:

A. Weakening immunity
B. Disease spread
C. Strengthening immunity
D. Addiction

Correct Answer: C
Explanation: Proper nutrition boosts immune response.

Q41. Drug abuse among adolescents is often due to:

A. Education
B. Peer pressure
C. Immunity
D. Vaccination

Correct Answer: B
Explanation: Peer pressure is a major cause.

Q42. Counselling helps in drug abuse prevention by:

A. Encouraging addiction
B. Reducing awareness
C. Providing emotional support
D. Increasing stress

Correct Answer: C
Explanation: Counselling builds confidence and coping skills.

Section J: Integrated & Board-Oriented MCQs

Q43. Which immunity is transferred from mother to child?

A. Active immunity
B. Artificial immunity
C. Passive immunity
D. Acquired immunity

Correct Answer: C
Explanation: Maternal antibodies provide passive immunity.

Q44. Which barrier secretes acid to kill pathogens?

A. Skin
B. Tears
C. Stomach
D. Lungs

Correct Answer: C
Explanation: Hydrochloric acid kills pathogens.

Q45. Which cell engulfs pathogens?

A. RBC
B. Platelet
C. Macrophage
D. Plasma cell

Correct Answer: C
Explanation: Macrophages perform phagocytosis.

Q46. Immunological memory is a feature of:

A. Innate immunity
B. Acquired immunity
C. Passive immunity
D. Natural barriers

Correct Answer: B
Explanation: Memory cells form only in acquired immunity.

Q47. Which practice increases disease risk?

A. Clean water
B. Vaccination
C. Poor sanitation
D. Balanced diet

Correct Answer: C
Explanation: Poor sanitation promotes infection.

Q48. Allergic reactions are treated using:

A. Antibiotics
B. Antihistamines
C. Vaccines
D. Antivirals

Correct Answer: B
Explanation: Antihistamines counter histamine effects.

Q49. Which disease is NOT infectious?

A. Malaria
B. Typhoid
C. Diabetes
D. Pneumonia

Correct Answer: C
Explanation: Diabetes does not spread by infection.

Q50. Human Health and Disease chapter mainly emphasises:

A. Genetics only
B. Disease prevention and awareness
C. Evolution
D. Plant biology

Correct Answer: B
Explanation: The chapter links biology with health awareness and prevention.

✔ Strictly NCERT-Based | ✔ CBSE Board Pattern | ✔ Concept-Clearing MCQs

🎯 Targeting Exams Section

This MCQ set is specially designed for preparation of:

• CBSE Class 12 Biology Board Examination

• CBSE Pre-Board & School Unit Tests

• CBSE Compartment / Improvement Exams

• NEET (UG) – Concept Reinforcement Level

• State Board Class 12 Exams aligned with NCERT

Questions follow the latest CBSE competency-based MCQ pattern, focusing on conceptual clarity, application, and health-awareness themes.

🔑 Related Keyphrases 

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