Autotrophic organism: It can synthesize organic matter by itself, such as green plants (photosynthesis) and nitrifying bacteria (chemosynthesis).

Heterotrophs: I can't synthesize organic matter by myself. I can only absorb external organic matter, such as animals and parasites.

Chloroplasts exist in the green parts of algae, mosses and higher plants.

Chloroplast-free cells: animal cells, root tip cells, seeds, flowers and prokaryotic cells.

In this problem, trematodes are prokaryotes, which can carry out photosynthesis, but have no chloroplasts. Similarly, there are common Nostoc commune and common cyanobacteria.