_ are an essential nutrient for animals.
Energy Chemicals trees potatoes Acids allow growth store Proteins
A B C D E F G H
Proteins are an essential nutrient for heterotrophs .
Proteins are an essential nutrient for animals.
_ are an essential nutrient for animals. (A) Energy (B) Chemicals (C) trees (D) potatoes (E) Acids (F) allow growth (G) store (H) Proteins