431: Poliomyelitis is an epidemic virus infection. Which of the following is responsible for it?
(a) Rhabdo virus
(b) Entero virus
(c) Dengue virus
(d) Mumps virus
432: Endoscopy, a technique used to explore the stomach or other inner parts of the body is based on the phenomenon of
(a) total internal reflection
(b) interference
(c) diffraction
(d) polarisation
Explanation:
Endoscopy is based on the phenomenon of Total Internal Reflection.
433: Rennin and lactase, the enzymes required to digest milk, disappear in the human body by the age of
(a) two
(b) three
(c) five
(d) eight
434: The increasing amount of carbon dioxide in the air is slowly raising the temperature of the atmosphere, because it absorbs
(a) the water vapour of the air and retains its heat
(b) the ultraviolet part of the solar radiation
(c) all the solar radiations
(d) the infrared part of the solar radiation
Explanation:
Option (D) is the correct reason for raising the temperature of the atmosphere.
435: Consider the following which can be found in the ambient atmosphere:
1. Soot
2. Sulphur hexafluoride
3. Water vapour
Which of the above contribute to the warming up of the atmosphere ?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 3 only
(d) 1, 2 and 3
Explanation:
Soot is a black, powdery substance that consists mainly of carbon and is formed through the incomplete combustion of wood, coal, diesel oil, or other materials. Because it absorbs energy from sunlight rather than reflecting it, soot is believed to be a cause of global warming, especially when it settles on snow and ice, reducing their reflectivity.
The SF6 molecule is very reflective and contributes to the greenhouse effect. But the concentration of the gas is extremely low (0.000'000'000'003 by volume). This means that the contribution of SF6 to the man-made greenhouse effect is very little, less than 0.1 percent of the total effect.
Water vapour is the most important greenhouse gas. If you get a fall evening and the sky is clear, heat will escape, the temperature will drop. If there's cloud cover, the heat is trapped by water vapour and the temperature stays warm.