Question

What is the size of the E. coli bacteria?
(A) $500nm$
(B) $1000nm$
(C) $2000nm$
(D) $3000nm$

Answer 1

Hint: A nanometer is one in the millionth of the millimetre or it is one in billionth of the metre. Since the E-coli is so small it cannot be seen by our eye or even through the light microscope. So, the E-coli has to be observed through Electron microscope (EM) or through the Scanning Probe Microscope (SEM).

Complete answer:
E. coli which is also known as is a prokaryotic organism that is the organisms that lack a definite nucleus, it is rod-shaped bacterium or bacillus with round ends. The Cells of E. coli can form long filaments. E.coli is usually a single cell organism which is capable of motion in liquid or semisolid environment with a tail-like projection called the flagella and its surface of the body is covered with a series of thread-like projections called the fimbriae.

The structures such as the flagella and the fimbriae are far too thin to be envisioned by traditional light microscopes. The E. coli is also not stable under a regular light microscope. The reason that is the E. coli bacterium or bacillus measures from $0.5\mu m$ in width and $2\mu m$ in length that is $2000nm$ it can only be seen under the Electron microscope (EM) or the Scanning Probe Microscope (SEM).

Therefore, the size of the E. coli is $2000nm$ .

Hence, the option (C) $2000nm$ is the correct answer.

Note: E. coli is a frequently found bacteria in the intestines of humans and further animals. Some strains of this bacteria can result in serious food poisoning. Humans can get E. coli infection by eating infected food, for example beef. While processing the meat the infection in the intestines can pass to the meat.