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NCERT Exemplar · Class 9 Science Why Do We Fall Ill

39 questions · 39 still being checked

Multiple Choice Questions 1–10 (part 1 of 4)

  1. Exercise 1

    Which one of the following is not a viral disease?
    (a)
    Dengue
    (b)
    AIDS
    (c)
    Typhoid
    (d)
    Influenza

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    NCERT’s answer
    (c)
    (c) Typhoid is bacterial (\(\displaystyle \textit{Salmonella typhi}\)); dengue, AIDS and influenza are all viral diseases.

  2. Exercise 2

    Which one of the following is not a bacterial disease?
    (a)
    Cholera
    (b)
    Tuberculosis
    (c)
    Anthrax
    (d)
    Influenza

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    NCERT’s answer
    (d)
    (d) Influenza is caused by a virus; cholera, tuberculosis and anthrax are all caused by bacteria.

  3. Exercise 3

    Which one of the following disease is not transmitted by mosquito?
    (a)
    Brain fever
    (b)
    Malaria
    (c)
    Typhoid
    (d)
    Dengue

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    NCERT’s answer
    (c)
    (c) Typhoid spreads through contaminated food and water; brain fever, malaria and dengue are all mosquito-borne.

  4. Exercise 4

    Which one of the following disease is caused by bacteria?
    (a)
    Typhoid
    (b)
    Anthrax
    (c)
    Tuberculosis
    (d)
    Malaria

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    NCERT’s printed answer for this exercise does not match its own question. This working follows the question as printed.

    (d) Typhoid, anthrax and tuberculosis are bacterial; malaria is caused by the protozoan \(\displaystyle \textit{Plasmodium}\), not a bacterium — the one NCERT's key marks, reading the stem as "not caused by bacteria" (the print above omits "not").Answer: (d) Malaria.NCERT prints: (d) — but the stem as printed asks which disease is caused by bacteria, and typhoid, anthrax and tuberculosis are all bacterial; only a stem reading "not caused by bacteria" makes (d) malaria the answer.

  5. Exercise 5

    Which one of the following diseases is caused by protozoans?
    (a)
    Malaria
    (b)
    Influenza
    (c)
    AIDS
    (d)
    Cholera

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    NCERT’s answer
    (a)
    (a) Malaria is caused by the protozoan \(\displaystyle \textit{Plasmodium}\); influenza and AIDS are viral, cholera is bacterial.

  6. Exercise 6

    Which one of the following has a long term effect on the health of an individual?
    (a)
    Common cold
    (b)
    Chicken pox
    (c)
    Chewing tobacco
    (d)
    Stress

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    NCERT’s answer
    (c)
    (c) Chewing tobacco causes lasting damage such as oral cancer; common cold and chicken pox clear up in days.

  7. Exercise 7

    Which of the following can make you ill if you come in contact with an
    infected person?
    (a)
    High blood pressure
    (b)
    Genetic abnormalities
    (c)
    Sneezing
    (d)
    Blood cancer

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    NCERT’s answer
    (c)
    (c) Sneezing throws out droplets carrying an infecting microbe, so standing near an infected person who sneezes can pass the disease on.

  8. Exercise 8

    AIDS cannot be transmitted by
    (a)
    sexual contact
    (b)
    hugs
    (c)
    breast feeding
    (d)
    blood transfusion

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    NCERT’s answer
    (b)
    (b) HIV needs an exchange of body fluids to pass between people; a hug carries no such exchange, so it cannot transmit AIDS.

  9. Exercise 9

    Making anti-viral drugs is more difficult than making anti-bacterial
    medicines because
    (a)
    viruses make use of host machinery
    (b)
    viruses are on the border line of living and non-living
    (c)
    viruses have very few biochemical mechanisms of their own
    (d)
    viruses have a protein coat

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    NCERT’s answer
    (c)
    (c) Viruses have very few biochemical mechanisms of their own, so they must use the host cell's machinery, leaving little for a drug to block that is not also part of the host.

  10. Exercise 10

    Which one of the following causes kala-azar?
    (a)
    Ascaris
    (b)
    Trypanosoma
    (c)
    Leishmania
    (d)
    Bacteria

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    NCERT’s answer
    (c)
    (c) Kala-azar (visceral leishmaniasis) is caused by the protozoan \(\displaystyle \textit{Leishmania}\), carried by the sandfly.