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Human Health and Diseases

Tamil Nadu Board · Class 12 · Zoology

Quick revision notes for Human Health and Diseases — Tamil Nadu Board Class 12 Zoology. Key concepts, formulas, and definitions for last-minute revision.

45 questions30 flashcards5 concepts

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Key Topics to Revise

1

Classification of Diseases

  • Diseases are broadly classified into Infectious (Communicable) and Non-Infectious (Non-Communicable) diseases.
  • Infectious diseases are caused by pathogens (virus, bacteria, fungi, protozoa, helminths) and are transmitted through air, water, food, physical contact, or vectors.
  • Non-infectious diseases are NOT transmitted from person to person; they include genetic (cystic fibrosis), nutritional (vitamin deficiency), and degenerative (arthritis, heart disease) disorders.
2

Bacterial Diseases

  • Shigellosis (Bacillary Dysentery): Caused by Shigella sp.; transmitted via faecal–oral route; symptoms include abdominal pain, blood and mucus in stools.
  • Bubonic Plague (Black Death): Caused by Yersinia pestis; vector is rat flea Xenopsylla cheopis; symptoms include fever, swollen lymph nodes (buboes).
  • Diphtheria: Caused by Corynebacterium diphtheriae; spread by droplet infection; affects larynx, skin, nasal and genital passages.
3

Viral Diseases

  • Viruses are the smallest intracellular obligate parasites that multiply only inside living cells.
  • Common Cold: Caused by Rhinoviruses (over 150 strains); difficult to vaccinate because RNA genome mutates constantly.
  • Mumps: Caused by Paramyxovirus (RNA virus); affects salivary glands; transmitted through saliva and droplets; causes enlargement of parotid glands.
4

Protozoan Diseases

  • About 15 genera of protozoans live as parasites in the human body.
  • Amoebiasis (Amoebic Dysentery): Caused by Entamoeba histolytica; lives in the large intestine; infective stage is trophozoite; carrier is housefly (Musca domestica).
  • African Sleeping Sickness: Caused by Trypanosoma species; transmitted by Tsetse fly (Glossina sp.).

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Full Notes

Key Concepts

Infectious diseases are disorders transmitted fromNonBacterial diseases are caused by pathogenicViruses are the smallest obligate intracellularAbout 15 genera of protozoans live

Frequently Asked Questions

What are the important topics in Human Health and Diseases for Tamil Nadu Board Class 12 Zoology?
Key topics in Human Health and Diseases include Chapter Overview – Human Health and Diseases, Overview of Human Diseases – Complete Classification, Human Health and Diseases - Comprehensive Overview. These are the concepts Tamil Nadu Board Class 12 examiners draw on most — study them first, then practise related questions.
How to score full marks in Human Health and Diseases — Tamil Nadu Board Class 12 Zoology?
Understand the core concepts first, then work through the 45 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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All 10 chapters — Tamil Nadu Board Class 12 Zoology Revision Notes

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