Diseases & Immunity — Homi Bhabha Class 9 Biology MCQs with Solutions
Free Homi Bhabha Class 9 Biology Diseases & Immunity MCQs with step-by-step solutions (13 questions). Part of Biotechnology & Applied Biology. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Diseases & Immunity · medium · theory
Diseases that spread from an infected person to a healthy person are called:
A. communicable (infectious) diseases ✓ Correct
B. non-communicable diseases
C. hereditary diseases
D. deficiency diseases
Solution: Communicable diseases are caused by pathogens and spread from person to person.
Q2 — Diseases & Immunity · hard · theory
A preparation that gives the body immunity against a particular disease is a:
A. vaccine ✓ Correct
B. painkiller
C. antibiotic
D. vitamin
Solution: A vaccine trains the immune system to protect against a specific disease.
Q3 — Diseases & Immunity · medium · theory
Which blood cells help defend the body against infection?
A. platelets only
B. white blood cells ✓ Correct
C. plasma
D. red blood cells
Solution: White blood cells fight infections as part of the immune system.
Q4 — Diseases & Immunity · hard · theory
Antibiotics are effective against ______ but NOT against ______:
A. viruses; bacteria
B. plants; animals
C. bacteria; viruses ✓ Correct
D. fungi; bacteria
Solution: Antibiotics work on bacteria; they do not kill viruses, so they cannot cure viral diseases like the common cold.
Q5 — Diseases & Immunity · medium · theory
Malaria and dengue are spread by:
A. mosquitoes (vectors) ✓ Correct
B. contaminated water only
C. touching
D. air
Solution: These are vector-borne diseases transmitted by mosquitoes.
Q6 — Diseases & Immunity · hard · theory
Which of the following is caused by a virus?
A. Cholera
B. Tuberculosis
C. Tetanus
D. AIDS ✓ Correct
Solution: AIDS is caused by the HIV virus; the others are bacterial diseases.
Q7 — Diseases & Immunity · medium · theory
The protective proteins produced by the body to fight against germs are called:
A. enzymes
B. antibodies ✓ Correct
C. antigens
D. hormones
Solution: Antibodies are produced by the immune system to neutralise pathogens (antigens).
Q8 — Diseases & Immunity · hard · theory
Giving vaccines to children to protect them from diseases is called:
A. digestion
B. fermentation
C. immunisation (vaccination) ✓ Correct
D. pollination
Solution: Immunisation uses vaccines to build immunity and prevent diseases such as polio and measles.
Q9 — Diseases & Immunity · easy · theory
Malaria, spread by the bite of a female Anopheles mosquito, is caused by which kind of organism?
A. A bacterium
B. A virus
C. A protozoan (Plasmodium) ✓ Correct
D. A fungus
Solution: Malaria is caused by the protozoan Plasmodium, which the female Anopheles mosquito transfers into the blood while biting. It is neither a bacterium nor a virus.
Q10 — Diseases & Immunity · easy · theory
A preparation given to a healthy person to make the body build protection against a particular disease in advance is called a:
A. Vaccine ✓ Correct
B. Antacid
C. Painkiller
D. Antibiotic
Solution: A vaccine contains weakened or dead germs (or their parts) that train the immune system to make defences, so the person is protected before the real infection. Antibiotics instead treat existing bacterial infections.
Q11 — Diseases & Immunity · medium · theory
A doctor explains that antibiotics can cure many bacterial infections but will NOT help against the common cold. This is because the common cold is caused by:
A. A lack of vitamins
B. Dirty food and water
C. A virus, which antibiotics do not act on ✓ Correct
D. A bacterium that is too small
Solution: The common cold is a viral infection, and antibiotics act only on bacteria, not on viruses. That is why taking antibiotics for a cold is ineffective and unnecessary.
Q12 — Diseases & Immunity · medium · theory
Which component of blood mainly defends the body by fighting and destroying invading germs?
A. Water in plasma
B. Red blood cells
C. White blood cells ✓ Correct
D. Platelets
Solution: White blood cells (leucocytes) engulf germs and produce antibodies, forming the bodys main defence. Red blood cells carry oxygen and platelets help blood to clot at wounds.
Q13 — Diseases & Immunity · hard · theory
Assertion (A): A person who has had chickenpox once usually does not catch it again. Reason (R): After an infection the body keeps special memory cells that quickly fight the same germ if it returns. Choose the correct option:
A. Both A and R are true but R does not explain A
B. A is true but R is false
C. A is false but R is true
D. Both A and R are true and R correctly explains A ✓ Correct
Solution: Recovery from chickenpox gives lasting immunity, and the reason is correct: memory cells remain and mount a fast, strong response on re-exposure, preventing the disease. So R correctly explains A.