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NCERT Exemplar · Class 9 Science Why Do We Fall Ill

39 questions · 39 still being checked

Multiple Choice Questions 11–18 (part 2 of 4)

  1. Exercise 11

    If you live in a overcrowded and poorly ventilated house, it is possible that
    you may suffer from which of the following diseases
    (a)
    Cancer
    (b)
    AIDS
    (c)
    Air borne diseases
    (d)
    Cholera

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    NCERT’s answer
    (c)
    (c) Crowding and poor ventilation let droplets carrying microbes build up and pass easily from person to person, spreading air-borne diseases.

  2. Exercise 12

    Which disease is not transmitted by mosquitoes?
    (a)
    Dengue
    (b)
    Malaria
    (c)
    Brain fever or encephalitis
    (d)
    Pneumonia

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    NCERT’s answer
    (d)
    (d) Pneumonia is a lung infection spread through the air by droplets, not by a mosquito bite; dengue, malaria and brain fever all need a mosquito vector.

  3. Exercise 13

    Which one of the following is not important for individual health?
    (a)
    Living in clean space
    (b)
    Good economic condition
    (c)
    Social equality and harmony
    (d)
    Living in a large and well furnished house
    WHY DO WE FALL ILL

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    NCERT’s answer
    (d)
    (d) Living in a large and well furnished house. Cleanliness, economic security and social harmony directly affect health; the size or furnishing of a house does not.

  4. Exercise 14

    Choose the wrong statement
    (a)
    High blood pressure is caused by excessive weight and lack of exercise.
    (b)
    Cancers can be caused by genetic abnormalities
    (c)
    Peptic ulcers are caused by eating acidic food
    (d)
    Acne in not caused by staphylococci

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    NCERT’s answer
    (c)
    (c) Peptic ulcers are caused by the bacterium \(\displaystyle \textit{Helicobacter pylori}\), not by eating acidic food.

  5. Exercise 15

    We should not allow mosquitoes to breed in our surroundings because
    they
    (a)
    multiply very fast and cause pollution
    (b)
    are vectors for many diseases
    (c)
    bite and cause skin diseases
    (d)
    are not important insects

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    NCERT’s answer
    (b)
    (b) They are vectors for many diseases. Mosquitoes carry malaria, dengue, chikungunya and filaria pathogens between people; stopping their breeding cuts these diseases at the source.

  6. Exercise 16

    You are aware of Polio Eradication Programme in your city. Children are
    vaccinated because
    (a)
    vaccination kills the polio causing microorganisms
    (b)
    prevents the entry of polio causing organism
    (c)
    it creates immunity in the body
    (d)
    all the above

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    NCERT’s answer
    (c)
    (c) It creates immunity in the body. The vaccine primes the immune system to raise antibodies and memory cells against the polio virus, without causing the disease itself.

  7. Exercise 17

    Viruses, which cause hepatitis, are transmitted through
    (a)
    air
    (b)
    water
    (c)
    food
    (d)
    personal contact

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    NCERT’s answer
    (b)
    (b) Water. Hepatitis viruses (A and E) spread through water contaminated with the faeces of infected people, the same route as cholera and typhoid.Answer: (b) Water.

  8. Exercise 18

    Vectors can be defined as
    (a)
    animals carry the infecting agents from sick person to another healthy
    person
    (b)
    microorganisms which cause many diseases
    (c)
    infected person
    (d)
    diseased plants

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    NCERT’s answer
    (a)
    (a) Animals carry the infecting agents from a sick person to another healthy person. A vector is the carrier itself, not the microorganism, the patient, or a diseased plant.