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CBSE Gujarat Board Haryana Board

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Class 10 Class 12

Which two of the following changes (1-4) usually tend to occur in the plain dwellers when they move to high altitudes (3500 m or more)?
1) Increase in red blood cell size
2) Increase in red blood cell production
3) Increase in breathing rate
4) Increase in thrombocytes count
Changes occurring are

  • (2) and (3)

  • (3) and (4)

  • (1) and (4)

  • (1) and (2)


A.

(2) and (3)

When a person moves to higher altitudes, the PO2 and total atmospheric pressure decrease. Hypoxia stimulates the JG - cells of the kidney to release erythropoietin hormone, which stimulates erythropoiesis in bone marrow causing polycythemia. Hypoxia will also increase breathing rate. Initially, the size of RBCs will also increase but with an increase in number of RBCs, the size of RBCs becomes normal.

When a person moves to higher altitudes, the PO2 and total atmospheric pressure decrease. Hypoxia stimulates the JG - cells of the kidney to release erythropoietin hormone, which stimulates erythropoiesis in bone marrow causing polycythemia. Hypoxia will also increase breathing rate. Initially, the size of RBCs will also increase but with an increase in number of RBCs, the size of RBCs becomes normal.


Ozone depletion will cause :
  • Forest fire
  • Pneumonia
  • Increased incidence of skin cancer
  • None of these

C.

Increased incidence of skin cancer

In the scrubber in the electrostatic precipitator the gases are passed through :
  • filter
  • lime
  • spray of water
  • both 2 and 3

D.

both 2 and 3

What is the term for the inflammation of cornea due to high absorption of UV-B radiation :
  • myopia
  • snow blindness
  • biomagnification
  • None of the above

B.

snow blindness

Which of the following pollutants is not produced by exhaust of motor vehicles ?
  • CO
  • Hydrocarbon
  • Fly-ash
  • NO

C.

Fly-ash

The meaning of BOD is :
  • Bacterial oxygen demand
  • Biological optimum density
  • Biochemical oxygen demand
  • Bioorganisation decay

C.

Biochemical oxygen demand