Chapter 8, Problem 20A

Summary Introduction

Introduction:

Photosynthesis is a process in which light energy from the Sun is converted to chemical energy for use by the cell. Chloroplasts are the organelles which capture light energy. A colored molecule that absorbs light is called a pigment. Pigments differ in their ability to absorb specific wavelengths of light.

Answer to Problem 20A

Correct answer :

The correct answer is option B. 500

Explanation of Solution

Explanation/justification for the correct answer:

Option B. 500- There are many types of pigments but the most common one is chlorophyll.

Besides chlorophyll there are other pigments called accessory pigments that trap additional light energy from other areas of visible spectrum. Carotenoid such as beta- carotene is an accessory pigment that absorbs light mainly in the blue and green region of spectrum while reflecting light in yellow, orange and red regions.

From the given illustration we can see that the maximum percentage of light absorbed by carotenoid is highest near the 500 wavelength of light. It also falls in the blue- green region of visible spectrum. Hence, this is the correct option.

Explanation for incorrect answer:

Option A. 400- This is violet- blue region of the visible spectrum where chlorophyll absorbs most light. Hence, this is not the correct option.

Option C. 600- In this region carotenoids absorb least amount of light. Hence, this is not the correct option.

Option D. 700- Between 600 to700, carotenoids absorb little amount of light but this is not maximum percentage of absorption. Hence, this is not the correct option.