The average size of most bacterial cells is __.
A) 1-5 micrometers
B) 1-5 picometers
C) 1-5 nanometers
D) 1-5 millimeters
The correct answer and explanation is:
The correct answer is A) 1-5 micrometers.
Bacterial cells are typically between 1 and 5 micrometers in length. This range is considered the average size for most prokaryotic cells, which includes a variety of bacterial species. These cells are much smaller than eukaryotic cells, which generally range from 10 to 100 micrometers in diameter. The size of bacteria allows for efficient nutrient uptake, rapid division, and adaptability in various environments. Bacteria may have different shapes, such as spherical (cocci), rod-shaped (bacilli), or spiral (spirilla), but their size remains within this general range.
The reason bacterial cells are typically so small is primarily related to surface area-to-volume ratio. A higher ratio allows bacteria to exchange materials, like nutrients and waste, more effectively with their environment. Larger cells would have more difficulty achieving this balance, limiting their growth and survival. Smaller bacteria can also divide rapidly, which is beneficial in environments where resources are abundant.
In contrast, picometers (B), nanometers (C), and millimeters (D) represent different scales. A picometer is one trillionth of a meter, which is far too small for even viruses. A nanometer is one billionth of a meter, and is the size scale of molecules and some small viruses. A millimeter is a thousand times larger than a micrometer and represents the size of larger organisms or structures.
Thus, bacterial cells fall within the micrometer range, which is optimal for their function and survival.