Chapter 19 — Health and Diseases: Multiple Choice Questions
1. The causative organism of malaria is ______.
2. The vector for dengue fever is ______.
- Malaria: Female Anopheles mosquito
- Dengue, Chikungunya, Zika: Aedes aegypti (breeds in clean stagnant water, bites during day)
- Filariasis (elephantiasis): Culex mosquito
- Plague: Rat flea
3. BCG vaccine is given to prevent ______.
4. AIDS is caused by ______.
5. The disease caused by deficiency of Vitamin C is ______.
- Vitamin A deficiency → Night blindness, xerophthalmia
- Vitamin C deficiency → Scurvy (bleeding gums, weak blood vessels)
- Vitamin D deficiency → Rickets (in children), osteomalacia (in adults)
- Vitamin B₁ (thiamine) deficiency → Beriberi
6. The immunity produced by vaccines is called ______.
- Active acquired immunity: Body produces its own antibodies after exposure to antigen (infection or vaccination). Long-lasting (memory cells formed).
- Passive acquired immunity: Ready-made antibodies transferred from another source (mother's milk, antiserum injection). Short-lived — no memory cells.
- Vaccines give active immunity by introducing weakened/killed pathogens or their antigens.
7. Tuberculosis is caused by ______.
8. Cholera is transmitted through ______.
9. An antigen is ______.
- Antigen: Any foreign substance (protein, polysaccharide) that triggers the body's immune response. Usually on the surface of pathogens.
- Antibody: Protein produced by B-lymphocytes (plasma cells) in response to antigens. Highly specific — each antibody binds to a particular antigen. Also called immunoglobulins (Ig).
10. Diabetes mellitus is caused by ______.
- Type 1: Absolute deficiency of insulin (autoimmune destruction of beta cells)
- Type 2: Insulin resistance + relative deficiency
Insulin (produced by beta cells of pancreatic islets of Langerhans) lowers blood glucose. Without insulin, blood glucose rises (hyperglycaemia). Symptoms: excess urination, thirst, hunger, weight loss. Treatment: insulin injections (Type 1), lifestyle changes + oral drugs (Type 2).
Quick Revision — Common Diseases
| Disease | Causative Agent | Transmission |
|---|---|---|
| Malaria | Plasmodium (protozoan) | Female Anopheles mosquito |
| Dengue | Dengue virus | Aedes mosquito |
| Tuberculosis | Mycobacterium tuberculosis | Airborne |
| Cholera | Vibrio cholerae | Contaminated water/food |
| AIDS | HIV (virus) | Blood, sexual contact |
| COVID-19 | SARS-CoV-2 (virus) | Respiratory droplets |
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Frequently Asked Questions
Communicable (infectious) diseases: caused by pathogens (bacteria, viruses, fungi, parasites), can spread from person to person. Examples: cholera, tuberculosis, malaria, COVID-19. Non-communicable diseases: cannot spread, caused by lifestyle/genetic factors. Examples: diabetes, heart disease, cancer, hypertension.