Question

Photosynthetically least efficient radiation is ---------.

• A. Blue
• B. Yellow
• C. Green
• D. Red

Answer 1

The correct option is C Green

Photosynthetically Active Radiation or PAR refers to the wavelength of light in the range that is best for photosynthesis. The optimal light energy required for the photosynthetic process by the living organism is the visible light in the range between 400 to 700 nanometer (nm). Photons of shorter wavelength tend to damage the cells and tissues due to the high energy levels and photons of longer wavelength do not carry enough to enable photosynthesis. Chlorophyll which is the abundant plant pigment absorbs red and blue light making it photosynthetically efficient. The green wavelengths are reflected giving leaves the green colour. Thus green is the photosynthetically least efficient wavelength.

So, the correct answer is 'Green'