Question

why plants have two types of chlorophyll instead of just one. How does this benefit them? What would you expect concerning the rate of photosynthesis for a plant that had only one type of chlorophyll?

Answer 1

Different types of chlorophyll are a result of evolution: diversity generated through evolutionary processes, mostly differenciated by the wavelenght of light that they absorb, their efficiency and function. Most plants have chlorophyll a and b, but there are also other types of chrlorophyll in less evolved vegetal organisms ike algae and cyanobacteria.

In the case of plants that have chlorophyll a and b (most plants), the benefit is that one type of chlorophyll (a) is very efficient at absorbing energy from wavelenghts of violet-blue and orange-red light, while the other type (chlorophyll b) functions as an accesory pigment, absorbing other wavelenghts of light and transferring them to chlorophyll a. This improves light absorbtion (therefore photynthesis rate) and also gives some plants the capacity to adapt to shade environments. Such plants tend to have more chlorophyll b in their chloroplasts and.

A plant with only one type of chlorophyll would be less adaptable to shade environments and it would absorb less light, so it would have lower photosynthesis rates.