A. The situation described is an example of phagocytosis, which is the process by which cells engulf large particles or other cells. In this case, a white blood cell is engulfing a bacterial cell to destroy it. Phagocytosis is an important mechanism of the immune system to protect the body against foreign invaders.
B. The situation described is an example of pinocytosis, which is the process by which cells absorb dissolved substances, such as nutrients, from the extracellular fluid. In this case, a protist cell is absorbing dissolved food particles to obtain nutrients for its metabolism. Pinocytosis is a common process in many types of cells to take up molecules from the environment.