Question

Chlorophyll f, which occurs in some species of cyanobacteria that grow under low illumination, has an absorption maximum of 706 nm, whereas other types of chlorophylls show absorption maxima at shorter wavelengths. Why is it advantageous for the cyanobacteria to produce chlorophyll f?

Short answer

The cyanobacteria can gather more low-energy (longer wavelength) light to use for photosynthesis because of the longer-wavelength absorption maximum.

Step-by-step solution

Cyanobacteria’s maximum absorption 

Chlorophyll $\mathrm{f}$ is found in cyanobacteria that grow in low-light environments. They have a maximum absorption wavelength of 706 nm, which is longer.

Difference between the proportion of low and high-energy light

There is a high proportion of long-wavelength low energy light in low-light environments.

On the other side, there is a high proportion of short-wavelength high-energy light in high-light environments.

Cause of advantages for the cyanobacteria

In cyanobacteria, chlorophyll f may absorb the most infrared light with a longer wavelength. Its maximum absorption wavelength is 706 nm. When the wavelength is longer, this is beneficial to the cyanobacteria since the frequency and energy are lower.Chlorophyll f allows the cyanobacteria to survive in conditions where there are very few photosynthetically active radiations. As a result, the bacteria can accumulate more low-energy light for photosynthesis because of the absorption maximum at longer wavelengths (far-red).

Hence, it is advantageous for cyanobacteria to produce chlorophyll f.