🩺 Why Do We Fall Ill – Class 9 Science MCQs

Section 1: Health, Disease & Causes of Diseases (Q1–Q25)

Q1. Health is defined as:

A. Absence of disease
B. Feeling happy
C. State of physical, mental, and social well-being
D. Eating balanced diet

✅ Correct Answer: C. State of physical, mental, and social well-being

Explanation:

• A. Wrong: Absence of disease is not complete health.
• B. Wrong: Happiness alone ≠ health.
• C. Correct, WHO defines health as overall well-being.
• D. Balanced diet is part of health, not definition.

Q2. Disease literally means:

A. Comfort
B. Uneasiness or disturbed ease
C. Perfect health
D. Recovery

✅ Correct Answer: B. Uneasiness or disturbed ease

Q3. Which of these is a factor affecting health?

A. Social environment
B. Public cleanliness
C. Economic condition
D. All of these

✅ Correct Answer: D. All of these

Q4. Acute diseases last for:

A. Few days to weeks
B. Months to years
C. Lifetime
D. None

✅ Correct Answer: A. Few days to weeks

Explanation:

• Example: Cold, cough, typhoid.

Q5. Chronic diseases last for:

A. Few days
B. Long duration (months/years)
C. 1–2 weeks
D. Never end

✅ Correct Answer: B. Long duration (months/years)

Explanation:

• Example: Diabetes, TB.

Q6. One major difference between acute and chronic diseases is:

A. Acute cause long-term effects
B. Chronic cause long-term poor health
C. Acute diseases are never curable
D. Chronic always spread

✅ Correct Answer: B. Chronic cause long-term poor health

Q7. Which is not a chronic disease?

A. Diabetes
B. Hypertension
C. Common cold
D. Tuberculosis

✅ Correct Answer: C. Common cold

Q8. Infectious diseases spread by:

A. Deficiency of nutrients
B. Genetic defects
C. Micro-organisms
D. Mechanical injury

✅ Correct Answer: C. Micro-organisms

Q9. Non-infectious diseases include:

A. Cancer
B. Diabetes
C. Hypertension
D. All of these

✅ Correct Answer: D. All of these

Q10. Pathogens are:

A. Friendly bacteria
B. Disease-causing organisms
C. Nutrients
D. Hormones

✅ Correct Answer: B. Disease-causing organisms

Q11. Which of these is not a communicable disease?

A. AIDS
B. Tuberculosis
C. Diabetes
D. Malaria

✅ Correct Answer: C. Diabetes

Q12. Malaria spreads through:

A. Air
B. Food
C. Female Anopheles mosquito bite
D. Contact with patient

✅ Correct Answer: C. Female Anopheles mosquito bite

Q13. Diseases which spread from person to person are called:

A. Non-infectious
B. Communicable
C. Genetic
D. Deficiency diseases

✅ Correct Answer: B. Communicable

Q14. Which of the following is a viral disease?

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

✅ Correct Answer: D. AIDS

Q15. Tuberculosis is caused by:

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

✅ Correct Answer: C. Bacteria

Q16. Cholera spreads through:

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

✅ Correct Answer: A. Contaminated food and water

Q17. Which of these is a protozoan disease?

A. Malaria
B. Typhoid
C. Influenza
D. AIDS

✅ Correct Answer: A. Malaria

Q18. Which disease is not caused by micro-organism?

A. Diabetes
B. Tuberculosis
C. Influenza
D. Cholera

✅ Correct Answer: A. Diabetes

Q19. Example of air-borne disease:

A. Cholera
B. Tuberculosis
C. Malaria
D. AIDS

✅ Correct Answer: B. Tuberculosis

Q20. Example of water-borne disease:

A. Cholera
B. Typhoid
C. Both A and B
D. AIDS

✅ Correct Answer: C. Both A and B

Q21. Peptic ulcers are caused by:

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

✅ Correct Answer: B. Bacteria

Q22. Heart disease is:

A. Infectious
B. Non-infectious
C. Genetic
D. Air-borne

✅ Correct Answer: B. Non-infectious

Q23. High blood pressure is also called:

A. Hypertension
B. Hypotension
C. Diabetes
D. Stroke

✅ Correct Answer: A. Hypertension

Q24. Disease-causing viruses are mainly spread by:

A. Mosquito bites
B. Food and water
C. Air droplets
D. All of these

✅ Correct Answer: D. All of these

Q25. Cancer is an example of:

A. Infectious disease
B. Non-infectious disease
C. Deficiency disease
D. None

✅ Correct Answer: B. Non-infectious disease

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