[[1]] nutrition is a mode of nutrition in which organisms depend upon other organisms for food to survive. 

Heterotrophic nutrition is a mode of nutrition in which organisms depend upon other organisms for food to survive. 

They can't make their own food like green plants as they lack chlorophyll which aids in the food-making process i.e., photosynthesis.

Heterotrophic organisms have to take in all the organic substances they need to survive.