Microbiology is the scientific study of microorganisms, which are organisms and infectious agents that are too small to be seen clearly without the aid of microscopes or other magnification tool

A. Yeasts are multicellular fungi that reproduce by spore fragmentation: Multicellular fungi, such as molds, have hyphal structures and can reproduce via spore formation or fragmentation of mycelia. Yeasts, however, are unicellular and do not form multicellular hyphae under normal conditions.

B. Yeasts are unicellular fungi that reproduce by budding: Yeasts are single-celled eukaryotic fungi that reproduce primarily through asexual budding, where a new daughter cell forms as an outgrowth from the parent cell. Their unicellular structure and budding reproduction distinguish them from filamentous fungi.

C. Yeasts are prokaryotic organisms that divide by binary fission: Prokaryotic organisms, such as bacteria, lack a nucleus and organelles and reproduce primarily by binary fission. Yeasts are eukaryotic, containing a true nucleus and membrane-bound organelles, and although some yeast species may divide by fission, they are classified as eukaryotes.

D. Yeasts are photosynthetic eukaryotes with chloroplasts: Photosynthesis is carried out by plants and certain protists possessing chloroplasts. Yeasts lack chloroplasts and do not perform photosynthesis; they obtain energy through fermentation or aerobic respiration, depending on environmental conditions.

A. Pasteur: Louis Pasteur demonstrated that microorganisms are responsible for fermentation and spoilage, supporting the germ theory of disease. He developed vaccines for diseases like rabies and anthrax, but he did not formally establish the experimental criteria proving that a specific microbe causes a specific disease.

B. Lister: Joseph Lister introduced antiseptic surgical techniques using carbolic acid to reduce postoperative infections. His work applied germ theory to clinical practice but did not provide the experimental proof linking individual microbes to specific diseases.

C. Koch: Robert Koch formulated Koch’s postulates, a set of criteria that provide experimental proof that a particular microorganism causes a specific disease. By isolating the microbe, reproducing the disease in a susceptible host, and re-isolating the same organism, he established causation.

D. Wasserman: August von Wasserman developed the Wasserman test for syphilis, a diagnostic tool for detecting infection. While important in serology, his work did not establish causation between microbes and disease.

E. Semmelweis: Ignaz Semmelweis advocated hand hygiene to reduce puerperal fever in obstetric clinics. His observations linked contaminated hands to disease transmission, but he did not experimentally prove that a specific microorganism caused a specific disease.