Ace the Praxis II Biology Exam 2025 – Unleash Your Inner Scientist and Triumph!

Microfilaments are a key component of the cytoskeleton in eukaryotic cells and are primarily composed of actin proteins. One of their main functions involves providing structural support and facilitating cellular movements, such as cytoplasmic streaming and amoeboid motion. This ability to help change cell shape and enable movement is essential for processes like cell division, muscle contraction, and the migration of cells.

Their role in cytoplasmic movement illustrates their importance in maintaining the internal organization of the cell and allowing cell mobility. Amoeboid motion, specifically, is commonly associated with certain types of cells, such as amoebas and white blood cells, which change shape to move through tissues.

In contrast, the other options describe functions or structures that do not pertain to microfilaments. Microfilaments do not directly participate in energy production, signaling, nor do they form the outer membrane of cells, as their functions are more aligned with structural integrity and movement within the cell. Thus, the choice that recognizes microfilaments' involvement in cytoplasmic movement and amoeboid motion correctly highlights their critical role in cellular physiology.