Question

Who had a great contribution in the field of microbiology?
A. Leeuwenhoek
B. Pasteur
C. Spallanzani
D. All of the above

Answer 1

For several years before their eventual discovery, the presence of microorganisms was hypothesized. Jainism, following the teachings of Mahavira as early as the 6th century BCE, theorised the presence of unknown microbiological life.

Complete answer:
First we should know about cell walls to answer this question. The nonliving portion is described as a cell wall that covers the outermost layer of a cell. Its structure varies and is absorbent in nature according to the organism. The internal contents of the cell are separated from the external atmosphere by the cell wall. It also gives the cell as well as its organelles with structure, support, and defense. However, in eukaryotic plants, fungi, and several prokaryotic species, this cellular aspect is present exclusively.

Now, let us find the solution from the options-

Among the first people to study microorganisms, that used a microscope of his own invention, was Antonie van Leeuwenhoek (1632-1723), who created one of the most influential contributions to biology. The relation between such mechanisms and microorganisms was not made by Van Leeuwenhoek, but when using a microscope, he established that there were modes of life that were not visible with the naked eye.
Louis Pasteur (1822-1895) built on the observations of Spallanzani by exposing boiling broths to oxygen in vessels containing a screen to avoid the flow of all particles to the growth media. In vessels with no philtre at all, he also did this, with air being entered through a curved tube which prohibited dust particles from getting in contact with the broth. Pasteur assured that at the outset of his experiment, no microorganisms existed inside the broths by heating the broth beforehand.
Lazzaro Spallanzani (1729–1799) discovered that it can be sterilized by boiling broth to destroy any microorganisms in it. He also observed that once the broth was released to the sunlight, fresh microorganisms could only reside in the broth.

Thus, the correct option is option (D) All the above

Note: Cohn’s contemporaries were Robert Koch and Louis Pasteur, and they are also called the founders of contemporary microbiology and medical microbiology, respectively. Pasteur is most notable for his series of experiments aimed at refuting the then prevalent idea of spontaneous generation, reasserting the identification of microbiology as just a biological science.