Modifiers matching protist:

• larger,
• photosynthetic,
• related,
• ancient,
• unicellular,
• higher,
• parasitic,
• marine,
• primitive,
• eukaryotic,
• heterotrophic,
• fragile,
• smaller,

Simple categories matching heterotrophic:

• microorganism,
• animal,
• bacteria,
• eukaryote,
• organism,
• microbe,
• protist,
• cell,