Biology Class 12 NCERT Solutions: Chapter 8 Human Health and Part 2 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Q. 3 How does the transmission of each of the following diseases take place?

(a) Amoebiasis

(b) Malaria

(c) Ascariasis

(d) Pneumonia

Answer:

Table of Mode of Transmission
DiseaseCausative

organism

Mode of transmission
a.AmoebiasisEntamoeba histolyticaIt is a vector-borne disease that spreads by the means of contaminated food and water. The vector involved in the transmission of this disease is the
b.MalariaPlasmodium sp.It is a vector-borne disease that spreads by the biting of the female Anopheles
c.AscariasisAscaris LumbricoidesIt spreads via contaminated food and water.
d.PneumoniaStreptococcus PneumoniaIt spreads by the sputum of an infected person.

Q. 4 What measure would you take to prevent water-borne diseases?

Answer:

  • Water-borne diseases such as cholera, typhoid, hepatitis B, etc. spread by drinking contaminated water.
  • These water-borne diseases can be prevented by ensuring proper disposal of sewage, excreta, periodic cleaning.
  • Also, measures such as disinfecting community water reservoirs, boiling drinking water, etc. should be observed.
Water Borne Diseases

Q. 5 Discuss with your teacher what does ‘a suitable gene’ means, in the context of DNA vaccines.

Answer:

  • A ‘suitable gene’ refers to a specific DNA segment which can be injected into the cells of the host body to produce specific proteins.
  • This protein kills the specific disease causing organism in the host body and provides immunity.

Q. 6 Name the primary and secondary lymphoid organs.

Answer:

  • Primary lymphoid organs include the bone marrow and the thymus.

Secondary lymphoid organs are the spleen, lymph nodes, tonsils, Peyer՚s

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