Answer:
Euglena have diversed nutritional requirements. They are autotrophic when kept in light and heterotrophic when deprived of light.
The Euglena contains chloroplast in it to perform photosynthesis in the presence of light.
When the Euglena is kept in the dark it starts deriving energy from the organic matter around it and shows heterotrophic mode of nutrition.
When light will be provided to Euglena it will start resynthesizes its photosynthetic pigment and it will start perform photosynthesis.
