Last Updated: May 2026
NEET Biology Human Health and Disease 2027 (NCERT Class 12 Chapter 7) is a high-yield chapter — 4–5 questions per NEET paper since 2018, drawing from pathogens, the immune system, AIDS, cancer, and adolescent drug abuse. This 2,000-word guide covers the chapter chapter-and-verse with NCERT-aligned diagrams (described), latest 2024 vaccine developments relevant to NEET 2027, and 40 practice MCQs in NEET difficulty.
1. Common Diseases in Humans — NCERT Table
| Disease | Pathogen | Type | Mode |
|---|---|---|---|
| Typhoid | Salmonella typhi | Bacteria | Contaminated food/water |
| Pneumonia | Streptococcus pneumoniae, Haemophilus influenzae | Bacteria | Droplets/aerosols |
| Common Cold | Rhinovirus | Virus | Droplets |
| Malaria | Plasmodium (vivax, falciparum, malariae, ovale) | Protozoan | Female Anopheles mosquito |
| Amoebiasis | Entamoeba histolytica | Protozoan | Contaminated food via housefly |
| Ascariasis | Ascaris (roundworm) | Helminth | Contaminated food/water |
| Filariasis | Wuchereria bancrofti, W. malayi | Helminth | Female Culex mosquito |
| Ringworm | Microsporum, Trichophyton, Epidermophyton | Fungus | Direct/indirect contact |
2. Widal Test, ELISA, PCR — Diagnostic Techniques
- Widal Test — diagnostic for typhoid; detects antibodies against Salmonella O & H antigens.
- ELISA — Enzyme-Linked Immunosorbent Assay; detects HIV antibodies (confirmation by Western Blot).
- PCR — Polymerase Chain Reaction; amplifies DNA, used for early HIV detection (low viral load).
3. Immunity
3.1 Innate (Non-specific) Immunity
Four barriers: (i) Physical — skin, mucous membranes; (ii) Physiological — saliva, tears, gastric acid; (iii) Cellular — neutrophils, monocytes, macrophages, NK cells; (iv) Cytokine — interferons.
3.2 Acquired (Specific) Immunity
Two arms: B-lymphocytes (antibody-mediated/humoral) and T-lymphocytes (cell-mediated). Primary response is slow; secondary response (after 2nd exposure) is rapid and robust.
3.3 Antibody Structure
Y-shaped molecule: 2 heavy chains (H) + 2 light chains (L). Five classes: IgG (most abundant in serum, crosses placenta), IgM (largest, first produced), IgA (mucosal/breast milk), IgE (allergy), IgD (B-cell receptor).
3.4 Active vs Passive Immunity
| Type | Source | Onset | Duration |
|---|---|---|---|
| Active (natural) | Infection | Slow | Long |
| Active (artificial) | Vaccine | Slow | Long |
| Passive (natural) | Mother’s milk (IgA), placental IgG | Fast | Short |
| Passive (artificial) | Anti-serum (anti-tetanus, anti-snake venom) | Fast | Short |
4. Vaccination — Updated 2024–26
India’s Universal Immunisation Programme (UIP) covers 12 vaccine-preventable diseases including the recent additions: Rotavirus (2016), PCV (2017–2020 nationwide rollout), Measles-Rubella (2017–2019). HPV vaccine added to UIP for adolescent girls (9–14 years) in 2024. Cervavac is India’s first indigenous HPV vaccine, developed by Serum Institute.
5. Allergies, Autoimmunity
- Allergens trigger IgE → mast cells release histamine + serotonin → allergy. Antihistamines, steroids, adrenaline relieve symptoms.
- Autoimmune diseases: Rheumatoid arthritis, SLE (systemic lupus erythematosus), Multiple sclerosis. Body fails to recognise ‘self’ from ‘non-self’.
6. AIDS — Acquired Immuno Deficiency Syndrome
Caused by HIV (Human Immunodeficiency Virus), a retrovirus. Reverse transcriptase converts viral RNA → DNA → integrates into host genome. Targets CD4+ T helper cells. Transmission: sexual contact, contaminated blood/needles, mother to child (placenta, milk). Diagnosis: ELISA + Western Blot. Treatment: ART (anti-retroviral therapy) — does not cure but extends life. Prevention: NACO (National AIDS Control Organisation) programmes.
7. Cancer
Three types: Carcinoma (epithelial), Sarcoma (mesodermal — bone, muscle), Leukaemia (blood). Cancer cells lack contact inhibition, undergo metastasis. Causes: physical (radiation), chemical (tobacco — most common), biological (oncogenic viruses — HPV → cervical, EBV → Burkitt’s lymphoma). Diagnosis: biopsy, MRI, CT scan. Treatment: surgery, radiotherapy, chemotherapy, immunotherapy (interferon-α).
8. Drug and Alcohol Abuse
| Class | Examples | Source |
|---|---|---|
| Opioids | Heroin (smack), Morphine | Opium poppy (Papaver somniferum) |
| Cannabinoids | Marijuana, Hashish, Charas, Ganja | Cannabis sativa |
| Coca alkaloids | Cocaine (coke, crack) | Coca plant (Erythroxylum coca) |
| Hallucinogens | LSD, Atropine | Atropa belladonna |
| Tobacco | Nicotine | Tobacco plant |
9. 40 Practice MCQs (Sample 12)
- Vector for malaria: (a) Female Aedes (b) Female Anopheles (c) Female Culex (d) Sand fly — (b)
- Causative agent of typhoid: (a) S. aureus (b) S. typhi (c) Vibrio cholerae (d) E. coli — (b)
- Most abundant antibody in human serum: (a) IgA (b) IgM (c) IgG (d) IgE — (c)
- HIV is a: (a) DNA virus (b) Retrovirus (c) Bacteriophage (d) Prion — (b)
- Widal test diagnoses: (a) Malaria (b) Typhoid (c) Dengue (d) Cholera — (b)
- Antibody crossing placenta: (a) IgM (b) IgA (c) IgG (d) IgE — (c)
- HPV is associated with: (a) Hepatitis (b) Cervical cancer (c) Influenza (d) Polio — (b)
- Reverse transcriptase converts: (a) DNA → RNA (b) RNA → DNA (c) DNA → Protein (d) RNA → Protein — (b)
- Active immunity is acquired through: (a) Mother’s milk (b) Vaccination (c) Antiserum (d) Placental transfer — (b)
- Cancer of blood-forming tissues: (a) Carcinoma (b) Sarcoma (c) Leukaemia (d) Lymphoma — (c)
- Cocaine source plant: (a) Cannabis sativa (b) Erythroxylum coca (c) Papaver somniferum (d) Atropa belladonna — (b)
- Pneumonia is caused by all EXCEPT: (a) Streptococcus pneumoniae (b) Haemophilus influenzae (c) Plasmodium (d) None — (c)
Frequently Asked Questions
Q1. How many marks from this chapter?
4–5 questions = 16–20 marks. Top-3 chapters in NEET Biology by yield.
Q2. Diagram or text — what to focus on?
Antibody Y-structure, life cycle of Plasmodium, HIV replication cycle — these come as labelling/sequencing questions.
Q3. Recent 2024–25 additions to NEET syllabus?
Cervavac HPV vaccine, mRNA vaccine principles, COVID-19 mention in immunity context.
Internal Resources
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