2007 General Studies, all questions

UPSC Prelims 2007 · General Studies

Question 118: Science and Technology

Which of the following light types of light are strongly absorbed by plants:

aViolet and Orange
bBlue and Red
cIndigo and Yellow
dYellow and Violet

AnswerThe answer is (b).

Chlorophyll absorbs light most strongly in the blue and red parts of the spectrum, and these wavelengths drive most photosynthesis. Green light is mostly reflected, which is why leaves look green. Of the pairs offered, only blue and red are the strongly absorbed ones.

Why each option is right or wrong
  • (a) Violet is absorbed, but orange is absorbed less than red.
  • (b) Correct: blue and red are the most strongly absorbed.
  • (c) Yellow is absorbed weakly.
  • (d) Yellow is absorbed weakly.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2007, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.