Why Do We Fall Ill (Class 9 Science)

Health is a state of complete physical, mental, and social well-being. Diseases are caused by pathogens like bacteria, viruses, and fungi, and can be preve

Why Do We Fall Ill (Class 9 Science)

Health is a state of complete physical, mental, and social well-being. Diseases are caused by pathogens like bacteria, viruses, and fungi, and can be preve

✓ 100% Free ✓ No Login Needed ✓ NCERT / CBSE Aligned ✓ Download as PDF

TL;DR: Health is a state of complete physical, mental, and social well-being. Diseases are caused by pathogens like bacteria, viruses, and fungi, and can be…

Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated

🤖 Stuck on any question? Ask Syllab's free AI Tutor for a step-by-step explanation — instant, unlimited, no login.

Health is a state of complete physical, mental, and social well-being. Diseases are caused by pathogens like bacteria, viruses, and fungi, and can be preve

Why Do We Fall Ill MCQs with Answers & Explanations

Q1. Which of the following is NOT a characteristic of a healthy person?

  1. Social well-being
  2. Good physical fitness
  3. Mental stress and anxiety ✓ (correct)
  4. Good immunity

Explanation: Health includes physical, mental, and social well-being. Mental stress and anxiety indicate poor mental health.

Q2. Communicable diseases are transmitted through:

  1. Genetic defects
  2. Poor nutrition
  3. Genes only
  4. Pathogens via direct or indirect contact ✓ (correct)

Explanation: Communicable diseases are spread by disease-causing pathogens (bacteria, viruses, fungi, protozoans) through direct contact, air, water, or vectors.

Q3. Which pathogen causes tuberculosis (TB)?

  1. Bacterium ✓ (correct)
  2. Protozoan
  3. Fungus
  4. Virus

Explanation: Tuberculosis is caused by Mycobacterium tuberculosis, a bacterium that primarily affects the lungs.

Q4. Polio is a disease caused by:

  1. Fungus
  2. Virus ✓ (correct)
  3. Bacteria
  4. Protozoan

Explanation: Polio is caused by the poliovirus, which is transmitted through contaminated food and water.

Q5. Which of the following helps our body fight infections?

  1. Toxins
  2. Pathogens
  3. Antibodies ✓ (correct)
  4. White blood cells

Explanation: Antibodies are produced by the immune system to neutralize and destroy pathogens and their toxins.

Q6. A disease spread by mosquitoes is:

  1. Tuberculosis
  2. Tetanus
  3. Typhoid
  4. Malaria ✓ (correct)

Explanation: Malaria is transmitted by Anopheles mosquitoes carrying the Plasmodium parasite.

Q7. Which vaccination prevents measles?

  1. MMR vaccine ✓ (correct)
  2. Polio vaccine
  3. BCG vaccine
  4. Typhoid vaccine

Explanation: The MMR (Measles, Mumps, Rubella) vaccine provides immunity against measles and other diseases.

Q8. Antibiotics are effective against:

  1. Viral infections
  2. Bacterial infections ✓ (correct)
  3. All diseases
  4. Fungal infections only

Explanation: Antibiotics kill or inhibit bacterial growth but are ineffective against viruses, which is why antibiotics are not used to treat colds or flu.

Q9. Which of the following is a non-communicable disease?

  1. Cholera
  2. Chicken pox
  3. Diabetes ✓ (correct)
  4. Typhoid

Explanation: Diabetes is a non-communicable disease caused by insulin deficiency or resistance. The others are communicable diseases spread by pathogens.

Q10. Personal hygiene includes:

  1. Sharing toothbrushes
  2. Drinking contaminated water
  3. Not washing hands
  4. Regular bathing and clean clothes ✓ (correct)

Explanation: Good personal hygiene includes regular bathing, wearing clean clothes, and washing hands regularly, which prevents disease transmission.

Frequently Asked Questions

What is the difference between acute and chronic diseases?

Acute diseases develop suddenly and last for a short period (e.g., cold, flu), while chronic diseases develop slowly and persist for a long time (e.g., diabetes, heart disease).

How does vaccination provide immunity against diseases?

Vaccination introduces a weakened or inactive form of a pathogen (or its antigen) into the body, stimulating the immune system to produce antibodies without causing the disease, providing long-term protection.

More Class 9 Science MCQs

🤖 Stuck on any of these? Ask Syllab's free AI Tutor to explain step by step →