Final answer:
Euglena will act as consumers when there are other organisms for them to eat, and they can also act as primary producers through photosynthesis.
Step-by-step explanation:
Euglena will act as consumers when placed in an environment that has other organisms for them to eat. They can consume other organisms through phagocytosis or absorb solutes from their aquatic environment. Euglena can also act as primary producers by photosynthesizing and using sunlight to synthesize carbohydrates.