Which characteristic is typical for filamentous algae?

Filamentous algae are distinguished by their structural organization, where cells are connected end to end, forming long chains or filaments. This characteristic allows filamentous algae to grow in a linear pattern, contributing to their appearance in aquatic environments. The end-to-end arrangement enables them to efficiently utilize light and nutrients in the water, enhancing their growth and proliferation in various aquatic habitats.

In contrast, some options highlight characteristics that do not align with filamentous algae. For instance, cells organized in a branching structure may apply to other types of algae or aquatic plants but does not represent the typical linear structure of filamentous algae. Similarly, individuals being strictly single-celled describes unicellular algae, which are distinct from the multicellular arrangement seen in filamentous algae. Lastly, the presence of chlorophyll is essential for photosynthesis in most algae, including filamentous types, thus those cells do contain chlorophyll rather than lacking it.