National League for Nursing (NLN PAX) Practice Exam

To observe the endoplasmic reticulum within a cell, an electron microscope is essential due to the extremely small size of cellular organelles. The endoplasmic reticulum consists of intricate structures that are typically only a few nanometers in size, which far exceeds the resolving power of a light microscope. Light microscopes operate using visible light and have a resolution limit of about 200 nanometers, making them insufficient for viewing organelles like the endoplasmic reticulum.

Electron microscopes, on the other hand, utilize electron beams and can achieve resolutions that allow for the observation of structures at the nanometer scale. This capability enables researchers to visualize organelles such as the endoplasmic reticulum in greater detail, including its rough and smooth variations. The high-resolution imaging provided by electron microscopy is unparalleled in its ability to illustrate the complex architecture of cellular components.

In contrast, the other options listed—an ultracentrifuge and dissecting instruments—do not facilitate direct observation of cellular structures. An ultracentrifuge is used primarily for the separation of cellular components based on their density, and dissecting instruments are meant for macroscopic examination rather than microscopic analysis. Therefore, the electron microscope is the appropriate tool for this particular observation.