chlorophyll

definition: 
A green pigment, present in all green plants and in cyanobacteria, responsible for the absorption of light to provide energy for photosynthesis. Its molecule contains a magnesium atom held in a porphyrin ring.
sentence: 
The green colouring comes from chlorophyll, the same pigment that is found in foliage. Unlike plants, though, cyanobacteria lack a second kind of chlorophyll, known as chlorophyll b, which in concert with chlorophyll a helps plants capture light.
difficulty: 
easy
toefl frequency: 
1
toefl classification: