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NCERT Exemplar · Class 9 Science Why Do We Fall Ill

39 questions · 39 still being checked

Short Answer Questions 19–29 (part 3 of 4)

  1. Exercise 19

    Give two examples for each of the following
    (a)
    Acute diseases
    (b)
    Chronic diseases
    (c)
    Infectious diseases
    (d)
    Non-infectious diseases

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    NCERT’s answer
    (a)
    Viral fever, Flu (b) Elephantiasis, Tuberculosis (TB) (c) Small pox, Chicken pox (d) Diabetes, Goitre
    Acute — short duration, no lasting after-effect: common cold, typhoid. Chronic — persists a long time, wears the body down: tuberculosis, elephantiasis. Infectious — caused by a transmissible pathogen: common cold, typhoid. Non-infectious — not pathogen-transmitted: cancer, high blood pressure. Answer: (a) common cold, typhoid (b) tuberculosis, elephantiasis (c) common cold, typhoid (d) cancer, high blood pressure.

  2. Exercise 20

    Name two diseases caused by Protozoans What are their causal organisms?

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    NCERT’s answer
    (i)
    Sleeping sickness caused by Trypanosoma / Malaria by plasmodium (ii) Kala-azar caused by Leishmania
    Malaria — caused by the protozoan Plasmodium. Amoebic dysentery — caused by the protozoan Entamoeba histolytica. Answer: Malaria (Plasmodium) and amoebic dysentery (Entamoeba histolytica).

  3. Exercise 21

    Which bacterium causes peptic ulcers? Who discovered the above pathogen for the first time? WHY DO WE FALL ILL

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    NCERT’s answer
    (i)
    Helicobactor pylori (ii) Marshall and Warren.
    Peptic ulcers are caused by the bacterium Helicobacter pylori. Barry Marshall and Robin Warren first identified it, in 1982. Answer: Helicobacter pylori, discovered by Barry Marshall and Robin Warren.

  4. Exercise 22

    What is an antibiotic? Give two examples

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    NCERT’s answer
    Antibiotic is a chemical substance that kill bacteria, secreted by micro- organisms which can kill the pathogens. Examples, Penicillin and Streptomycin.
    An antibiotic is a substance produced by microorganisms that kills or stops the growth of bacteria. Answer: A substance produced by microorganisms that kills or halts bacterial growth; e.g. Penicillin, Streptomycin.

  5. Exercise 23

    Fill in the blanks
    (a)
    Pneumonia is an example of ——— disease.
    (b)
    Many skin diseases are caused by———.
    (c)
    Antibiotics commonly block biochemical pathways important for the
    growth of ———.
    (d)
    Living organisms carrying the infecting agents from one person to
    another are called ———.

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    NCERT’s answer
    (a)
    Communicable (b) Fungi (c) Bacteria (d) Vector
    (a)
    Pneumonia: a microbe causes it and it spreads person to person — infectious.
    (b)
    Ringworm and similar skin conditions — caused by fungi.
    (c)
    Antibiotics interrupt pathways bacteria need to grow, sparing human cells — bacteria.
    (d)
    An organism ferrying a pathogen from one host to another — vector.
    Answer: (a) infectious (b) fungi (c) bacteria (microbes) (d) vectors.

  6. Exercise 24

    Name the target organs for the following diseases
    (a)
    Hepatitis targets———.
    (b)
    Fits or unconsciousness targets ———.
    (c)
    Pneumonia targets ———.
    (d)
    Fungal disease targets ———.

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    NCERT’s answer
    (a)
    Liver (b) Brain (c) Lungs (d) Skin
    (a)
    Hepatitis — liver.
    (b)
    Fits or unconsciousness — brain.
    (c)
    Pneumonia — lungs.
    (d)
    Fungal disease — skin.
    Answer: (a) liver (b) brain (c) lungs (d) skin.

  7. Exercise 25

    Who discovered ‘vaccine’ for the first time? Name two diseases which can be prevented by using vaccines.

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    NCERT’s answer
    Edward Jenner. Example— Small pox, Polio
    Edward Jenner first used a vaccine, cowpox matter against smallpox, in 1796. Answer: Edward Jenner; vaccines guard against smallpox and polio.

  8. Exercise 26

    Fill in the blanks
    (a)
    ——— disease continues for many days and causes——— on body.
    (b)
    ———disease continues for a few days and causes no longer term effect
    on body.
    (c)
    ——— is defined as physical, mental and social well-being and comfort.
    (d)
    Common cold is——— disease.
    (e)
    Many skin diseases are caused by———.

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    NCERT’s answer
    (a)
    Chronic, long term effect (b) Acute (c) Health (d) Infectious/ communicable (e) Fungi
    (a)
    Persists many days, wears the body down over time — chronic; long-lasting ill-effects.
    (b)
    Lasts a few days, leaves no lasting mark — acute.
    (c)
    Well-being across body, mind and society together — health.
    (d)
    Spreads from person to person, brief course — infectious (communicable).
    (e)
    Ringworm and similar skin conditions — fungi.
    Answer: (a) Chronic; long-lasting effects (b) Acute (c) Health (d) infectious (communicable) (e) fungi.

  9. Exercise 27

    Classify the following diseases as infectious or non-infectious.
    (a)
    AIDS
    (b)
    Tuberculosis
    (c)
    Cholera
    (d)
    High blood pressure
    (e)
    Heart disease
    (f)
    Pneumonia
    (g)
    Cancer

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    NCERT’s answer
    (a)
    infectious (b) infectious (c) infectious (d) non-infectious (e) non-infectious (f) infectious (g) non-infectious
    An infectious disease passes from an infected person to a healthy one through a microbe; a non-infectious one does not spread this way.
    (a)
    AIDS — infectious
    (b)
    Tuberculosis — infectious
    (c)
    Cholera — infectious
    (d)
    High blood pressure — non-infectious
    (e)
    Heart disease — non-infectious
    (f)
    Pneumonia — infectious
    (g)
    Cancer — non-infectious
    Answer: Infectious: AIDS, Tuberculosis, Cholera, Pneumonia. Non-infectious: High blood pressure, Heart disease, Cancer.

  10. Exercise 28

    Name any two groups of micro-organisms from which antibiotics could be extracted.

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    NCERT’s answer
    Bacteria and fungi
    Fungi — e.g. \(\displaystyle \textit{Penicillium}\), the source of penicillin. Bacteria (actinomycetes) — e.g. \(\displaystyle \textit{Streptomyces}\), the source of streptomycin. Answer: Bacteria (e.g. \(\displaystyle \textit{Streptomyces}\)) and fungi (e.g. \(\displaystyle \textit{Penicillium}\)).

  11. Exercise 29

    Name any three diseases transmitted through vectors.

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    Malaria — spread by the \(\displaystyle \textit{Anopheles}\) mosquito. Dengue — spread by the \(\displaystyle \textit{Aedes}\) mosquito. Filariasis — spread by the \(\displaystyle \textit{Culex}\) mosquito.Answer: Malaria, dengue and filariasis.NCERT prints: Malaria, Dengue and Kala-azar — the question asks for any three, and filariasis (spread by the Culex mosquito) is an equally valid vector-borne disease in kala-azar's place.