The development of electron microscopy has provided key insights into many aspects of cellular structure and function, which had previously been too small to be seen. All of the following would require the use of electron microscopy for visualization EXCEPT (A) the structure of a bacteriophage (B) the matrix structure of a mitochondrion \(\quad\) (C) the shape and arrangement of bacterial cells \(\quad\) (D) the pores on the nuclear membrane

Electron microscopy is a powerful imaging technique that utilizes a beam of electrons, rather than light, to examine structures at a very high resolution. This allows scientists to visualize tiny structures that are beyond the resolving power of a light microscope, which is typically around 200 nm. Structures smaller than this threshold will require electron microscopy for proper visualization.

(A) The structure of a bacteriophage: Bacteriophages are viruses that infect bacteria, and their size ranges from 20-200 nm. Due to their small size and complex structure, electron microscopy is required to visualize them. (B) The matrix structure of a mitochondrion: The matrix of a mitochondrion contains many structures and proteins involved in respiration and metabolism within the organelle. Mitochondria are typically around 500 nm to 1 µm in size, but to see the details of the matrix structure, a higher resolution is required. Therefore, electron microscopy would be necessary to visualize the matrix structure of a mitochondrion. (C) The shape and arrangement of bacterial cells: Bacterial cells are larger than 200 nm, with most bacteria ranging in size from 0.5 µm to 5 µm. This means that the shape and arrangement of bacterial cells can be observed using a light microscope. Therefore, electron microscopy is not required for the visualization of bacterial cells' shape and arrangement. (D) The pores on the nuclear membrane: The nuclear membrane contains nuclear pores, which are complex protein structures with diameters of about 100 nm. The small size of these pores means that electron microscopy will be needed to visualize them.

Based on the analysis of each option, it is clear that option (C) - the shape and arrangement of bacterial cells - does NOT require the use of electron microscopy for visualization. The other three options (A, B, and D) involve structures that are too small or detailed to be visualized using a light microscope, making electron microscopy essential for their study. Therefore, the correct answer is (C).