Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

What is endocytosis?

1. The process of escaping harmful substances from inside the cell

2. The capture and intake of external substances by the cell membrane

3. The synthesis of proteins within the endoplasmic reticulum

4. The fusion of vesicles with the plasma membrane

The correct answer is: The capture and intake of external substances by the cell membrane

Endocytosis refers to the biological process in which a cell takes in external substances by engulfing them with its cell membrane. The key aspect of endocytosis is that the cell membrane folds inward, creating a pocket that eventually pinches off to form a vesicle containing the ingested substances. This process allows the cell to absorb nutrients, signaling molecules, and other important factors from its environment. This mechanism is crucial for various cellular functions, including nutrient uptake and regulation of signaling pathways. By facilitating the intake of vital components, endocytosis plays a significant role in maintaining cellular homeostasis and responding to changes in the environment. The other choices presented describe different cellular processes that do not accurately reflect the nature of endocytosis. For instance, the process of escaping substances from inside the cell pertains more to exocytosis, whereas protein synthesis occurs within the endoplasmic reticulum, and the fusion of vesicles with the plasma membrane relates to the release of substances from the cell, rather than the intake of them.