Question

Regarding assertion and reason choose the right option
Assertion [A]: Only some fraction of the total solar energy input is utilized by plants.
Reason [R]: Of the total solar radiation, only a certain spectrum is used by plants, and this region of the spectrum is called PAR.

• A. Both A and R are true and R explains A
• B. Both A and R are true R does not explain A
• C. A is true and R is false
• D. Both A and R are false

Answer 1

The correct option is A Both A and R are true and R explains A

Solar radiation forms a spectrum called the electromagnetic spectrum. In the spectrum, there are three relevant bands or ranges- UV, visible light and infrared. Of the total incident solar radiation or energy, only a fraction of it, which is light in the 400 to 700 nanometer wavelength range is capable of enabling photosynthesis. This proportion of radiation is known as photosynthetically active radiation or PAR. PAR also changes seasonally and varies depending on the latitude and time of day.