How large is the unknown bacterium that measures 1 ocular unit compared to the RBC, which is approximately 7µm in diameter?

To determine the size of the unknown bacterium based on the measurement of 1 ocular unit in relation to a red blood cell (RBC) of approximately 7 µm in diameter, it is essential to understand the ocular unit's calibration. Ocular units are typically measured through the microscope's eyepiece and represent a specific length at a given magnification.

In many microscopy settings, particularly in introductory labs, 1 ocular unit can correspond to a specific, standardized size. For example, at a common magnification setting, an ocular unit might typically equal around 10 µm. If this holds true in your case, and 1 ocular unit equals about 10 µm, the unknown bacterium measuring 1 ocular unit would indeed measure roughly 10 µm.

Considering that an RBC measures 7 µm, the measurement provides context for understanding cell and bacterial sizes. Since the unknown bacterium at 1 ocular unit (10 µm) is larger than the RBC, this aligns with general knowledge regarding the size range of certain bacteria, which can vary significantly but can also range from 1 µm to considerably larger sizes, depending on the species.

Thus, 10 µm is a plausible estimate for the size of the unknown