Problem 2 - AP Psychology Premium Prep 2021

Question

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

Step-by-Step Solution

Answer

The shape and arrangement of bacterial cells (C) can be resolved with light microscopy and does not require electron microscopy for visualization.

Step 1: Understand the concept of electron microscopy

Electron microscopy is a technique that uses a beam of electrons, instead of light, to create an image of the specimens. The wavelength of the electrons is much shorter than the wavelength of visible light, so electron microscopes have a much higher resolution power, allowing them to see much smaller structures than can be seen using a light microscope.

Step 2: Review the sizes of the structures mentioned in the options

We need to know the approximate sizes of the structures mentioned in each option to determine if electron microscopy is needed for visualization. (A) Bacteriophages are viruses that infect and replicate within bacteria, and they typically have a size range of 20-200 nm. This size range is below the resolution of light microscopy. (B) The matrix structure of a mitochondrion refers to the internal structure and organization of the organelle. Mitochondria are around 0.5 - 1.0 micrometers in diameter, but the internal matrix structure is highly organized and containing details below the resolution of light microscopy. (C) Bacterial cells are generally 0.5-5 micrometers in size. The shape and arrangement of bacterial cells can be resolved with light microscopy. (D) Pores on the nuclear membrane are protein structures that serve as passageways for molecules between the nucleus and cytoplasm. Nuclear pores have a diameter of about 100 nm, which is below the resolution of light microscopy.

Step 3: Determine which option does not require electron microscopy

From the previous step, we can see that: - (A) the structure of a bacteriophage, - (B) the matrix structure of a mitochondrion, and - (D) the pores on the nuclear membrane all have sizes or features that are below the resolution limit of light microscopy, so they require electron microscopy for visualization. However, (C) the shape and arrangement of bacterial cells are within the size range that can be resolved with light microscopy. Therefore, electron microscopy is not required for visualization. The answer is (C) the shape and arrangement of bacterial cells.