Final answer:
The statement is true; primary producers are indeed a mix of floating algae and attached algae, like phytoplankton and brown algae, which are essential for oxygen and organic matter production in aquatic ecosystems.
Step-by-step explanation:
Primary producers in the concept of ecology comprise a variety of organisms capable of producing energy from sunlight via photosynthesis. The statement that primary producers are a mix of floating algae and attached algae is true. Producers, including plants, algae, and diatoms, play crucial roles in ecosystems both terrestrial and aquatic. In aquatic environments, phytoplankton, which includes many forms of algae, are the predominant producers.
These microscopic organisms, such as the green phytoplankton that may be observed floating on the surface of a pond, are critical for the production of oxygen and organic matter. Algae can exist in many forms, including unicellular or multicellular, and can reside in the water column or attached to substrates. Examples like the multicellular brown algae (Phaeophyta) contribute significantly to marine ecosystems, with some species forming large structures such as kelp.