18. What is the group of
aquatic beings composed of a
large number of
photosynthetic beings?

Gap-fill exercise

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!
A large number of beings
is found in plankton, i.e., in the
of aquatic ecosystems.This is
light is abundant on
surface.