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Class 12 · Biology · Chapter 7

Human Health and Disease: Class 12 Important Questions with Answers

72 important questions for Class 12 Biology Chapter 7, Human Health and Disease, the way they come in the board exam: MCQs, assertion–reason, case-based and short and long answer questions, with answers. Taken from our Class 12 Biology notes for 2026-27.

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Jump to: Practice set: test yourself20 MCQsAssertion–ReasonAnswers to the practice set

Practice set: test yourself

Try every question before looking at the answers below. 64 or more out of 80 means you are ready for the board.

A. Fill in the blanks (1 mark each)

  1. Typhoid is confirmed by the ______ test.
  2. The toxin released when RBCs burst in malaria is ______.
  3. Elephantiasis is caused by ______.
  4. Interferons belong to ______ barriers.
  5. Antibodies of allergy are of type ______.
  6. HIV is a ______ (type of virus).
  7. Loss of contact inhibition leads to ______.
  8. Heroin is obtained by ______ of morphine.

B. True or false? (1 mark each)

  1. Common cold infects the lungs.
  2. P. falciparum causes the most serious malaria.
  3. Colostrum gives active immunity.
  4. T-cells are responsible for graft rejection.
  5. The spleen is a primary lymphoid organ.
  6. Benign tumours show metastasis.
  7. Nicotine raises blood pressure.
  8. Cocaine interferes with dopamine transport.

C. Very short answer (1 mark each)

  1. Name the fish used to control mosquito larvae.
  2. Which cells act as HIV factories?
  3. Name two fungi causing ringworm.
  4. Where do T-lymphocytes mature?
  5. Name one autoimmune disease.
  6. Name the mosquito that spreads dengue.
  7. Name the drug from the latex of poppy.
  8. Which antibody crosses the placenta?
  9. Name a biological response modifier used in cancer.
  10. Expand ELISA.

D. Short answer I (2 marks each)

  1. Distinguish humoral and cell-mediated immunity.
  2. Why is the secondary immune response stronger?
  3. Give two symptoms each of pneumonia and amoebiasis.
  4. What are the two barriers that protect the gut against pathogens?
  5. Why do malaria symptoms recur every 3–4 days?
  6. How do vaccines work?
  7. Name two techniques of cancer detection and how they work.
  8. Give two warning signs of drug abuse in adolescents.
My score (fill in after checking the answers)
SectionA /8B /8C /10D /16E /18F /20G (bonus)Total /80
My marks

Rough work

E. Short answer II (3 marks each)

  1. Describe four barriers of innate immunity.
  2. Explain the life cycle of Plasmodium in humans.
  3. What is allergy? Explain its mechanism and treatment.
  4. Describe the causes of cancer.
  5. Describe the structure of an antibody with a diagram.
  6. How does smoking harm the body?

F. Long answer (5 marks each)

  1. Describe how HIV causes AIDS, its transmission, diagnosis and prevention.
  2. Describe the primary and secondary lymphoid organs and their roles.

G. HOTS (higher-order thinking)

  1. Why are antibiotics useless against the common cold?
  2. Why are allergies more common in metro cities?
  3. Why do organ-transplant patients take immunosuppressants?
  4. Why should needles never be shared?

20 MCQs

  1. Typhoid is caused by
    (a) Streptococcus (b) Plasmodium (c) Salmonella typhi (d) rhinovirus
  2. Widal test is for
    (a) typhoid (b) malaria (c) AIDS (d) cancer
  3. Sporozoites are stored in the mosquito's
    (a) gut (b) wings (c) blood (d) salivary glands
  4. Elephantiasis is caused by
    (a) Ascaris (b) Wuchereria (c) Entamoeba (d) Trichophyton
  5. Ringworm is caused by
    (a) bacteria (b) fungi (c) viruses (d) worms
  6. Which is a physical barrier?
    (a) saliva (b) neutrophil (c) interferon (d) skin
  7. Antibodies are produced by
    (a) B-cells (b) T-cells (c) RBCs (d) platelets
  8. Colostrum is rich in
    (a) IgE (b) IgG (c) IgA (d) IgM
  9. Histamine is released by
    (a) neutrophils (b) T-cells (c) RBCs (d) mast cells
  10. Rheumatoid arthritis is
    (a) infectious (b) autoimmune (c) allergic (d) genetic only
  11. Primary lymphoid organ
    (a) spleen (b) lymph node (c) thymus (d) tonsil
  12. HIV first enters
    (a) macrophages (b) RBCs (c) B-cells (d) neurons
  13. Enzyme of HIV making DNA from RNA
    (a) DNA polymerase (b) reverse transcriptase (c) ligase (d) RNA polymerase
  14. Metastasis is shown by
    (a) benign tumours (b) normal cells (c) malignant tumours (d) all tumours
  15. Oncogenic viruses carry
    (a) proto-oncogenes (b) antigens only (c) interferons (d) viral oncogenes
  16. α-interferon is used in
    (a) immunotherapy of cancer (b) surgery (c) AIDS diagnosis (d) malaria
  17. Smack is chemically
    (a) diacetylmorphine (b) morphine (c) cocaine (d) cannabinoid
  18. Cannabinoids mainly affect
    (a) liver (b) skin (c) kidney (d) cardiovascular system
  19. Nicotine causes release of
    (a) insulin (b) adrenaline and nor-adrenaline (c) thyroxine (d) oxytocin
  20. The most vulnerable age for drug abuse
    (a) 5–10 (b) 30–40 (c) 12–18 (d) 60+

1 (c) · 2 (a) · 3 (d) · 4 (b) · 5 (b) · 6 (d) · 7 (a) · 8 (c) · 9 (d) · 10 (b) · 11 (c) · 12 (a) · 13 (b) · 14 (c) · 15 (d) · 16 (a) · 17 (a) · 18 (d) · 19 (b) · 20 (c)

Assertion–Reason (6)

(a) Both true, R explains A. (b) Both true, R does not explain A. (c) A true, R false. (d) A false, R true.

  1. A: Malaria fever recurs every 3–4 days. R: Infected RBCs burst and release haemozoin.
  2. A: Passive immunity is quick. R: Ready-made antibodies are given.
  3. A: Interferons protect non-infected cells. R: They are secreted by bacteria-infected cells.
  4. A: AIDS patients die of opportunistic infections. R: HIV destroys helper T-cells.
  5. A: Benign tumours spread through the body. R: Malignant cells show metastasis.
  6. A: Heroin is a stimulant. R: Heroin is obtained from morphine.

Key: 1 (a) · 2 (a) · 3 (c) · 4 (a) · 5 (d) · 6 (d)

Answers to the practice set

A. 1. Widal 2. haemozoin 3. Wuchereria (bancrofti, malayi) 4. cytokine 5. IgE 6. retrovirus 7. cancer (tumours) 8. acetylation

B. 1. F 2. T 3. F (passive) 4. T 5. F (secondary) 6. F 7. T 8. T

C. 1. Gambusia 2. macrophages 3. Microsporum, Trichophyton (Epidermophyton) 4. thymus 5. rheumatoid arthritis 6. Aedes 7. morphine 8. IgG 9. α-interferon 10. enzyme-linked immunosorbent assay

D. 1. Humoral: B-cells make antibodies in blood; cell-mediated: T-cells act directly, cause graft rejection 2. Memory B and T cells formed in the primary response respond faster and more strongly 3. Pneumonia: fever, chills, cough, bluish lips/nails (any two); amoebiasis: constipation, abdominal cramps, stools with mucus and blood 4. Mucus coating of the gut (physical); stomach acid and saliva (physiological) 5. The parasites multiply in RBCs and burst them in cycles, releasing haemozoin each time 6. Antigens in the vaccine make the body form antibodies and memory cells, which neutralise the real pathogen rapidly on later exposure 7. Biopsy (stained section examined), MRI (magnetic fields detect tissue changes), CT, X-rays (any two) 8. Falling grades, unexplained absence, poor hygiene, isolation, depression, aggressive behaviour, changed appetite or sleep (any two)

Answers to E, F, G, case study (short, long and HOTS answers, step by step) are in the notes pack

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