UPSC Prelims 2019 · GS Paper I
Question 32: Science and Technology
For the measurement/estimation of which of the following are satellite images/remote sensing data used?
- 1.Chlorophyll content in the vegetation of a specific location
- 2.Greenhouse gas emissions from rice paddies of a specific location
- 3.Land surface temperatures of a specific location
Select the correct answer using the code given below.
AnswerUPSC’s answer is (d).
Satellite images and remote sensing data are used for all three. Vegetation indices derived from satellite imagery reflect chlorophyll content and the health of vegetation. Methane emissions from flooded rice paddies can be estimated from satellite data on the area under rice, flooding and vegetation, combined with models. Thermal infrared sensors give land surface temperature. All three statements are therefore correct.
- 1. Vegetation indices from satellite images reflect chlorophyll content.
- 2. Paddy emissions can be estimated from satellite data and models.
- 3. Thermal sensors give land surface temperature.
How you could have got this
- If you were sure statement 1 is correct, (b) and (c) go: each of them leaves 1 out.
What you needed to know: Vegetation indices from satellite images reflect chlorophyll content.
- Then, if you were sure statement 2 is correct, (a) goes: it leaves 2 out.
What you needed to know: Paddy emissions can be estimated from satellite data and models.
Only (d) is left. You didn’t need statement 3.
Which options go is worked out from UPSC’s key and the options, not by a model.
Why each option is right or wrong
- (a) Remote sensing also covers the other two.
- (b) Chlorophyll content can also be measured from satellite data.
- (c) Remote sensing also measures chlorophyll and paddy emissions.
- (d) Correct: all three can be measured or estimated by remote sensing.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2019, General Studies Paper I, Series A. The paper on upsc.gov.in.