Final answer:
Endocytosis is the process of nutrient uptake by which small dissolved molecules are engulfed into vesicles, using energy in the form of ATP.
Step-by-step explanation:
The type of nutrient uptake that involves the engulfment of small dissolved molecules into vesicles is known as endocytosis. This process is a form of active transport, whereby the cell actively engulfs extracellular materials into vesicles using energy, typically in the form of adenosine triphosphate (ATP). There are different variations of endocytosis, including phagocytosis, pinocytosis, and receptor-mediated endocytosis, depending on the type of material ingested and the method of vesicle formation.