Question

Chlorophyll a is absent in which of the following photosynthesising organisms?

• A. Bacteria
• B. Cyanobacteria
• C. Red algae
• D. Brown algae

Answer 1

The correct option is A Bacteria

The main light-harvesting pigment in bacteria is not chlorophyll, but bacteriochlorophyll (BChl), a closely related magnesium porphyrin, that has a more saturated tetrapyrrole ring. This causes BChl to absorb at significantly longer wavelengths than chlorophyll in the near infrared, the absorbance spectrum being dictated by the details of the conjugated electron system of the macrocycle.

So, the correct answer is option A.