Premise: Chlorophyll (also chlorophyl) is any of several closely related green pigments found in cyanobacteria and the chloroplasts of algae and plants. Its name is derived from the Greek words χλωρός, "chloros" ("green") and φύλλον, "phyllon" ("leaf"). Chlorophyll is essential in photosynthesis, allowing plants to absorb energy from light.
Hypothesis: Chlorophyll is essential in photosynthesis, allowing plants to absorb energy from darkness.