Know the basic shapes of the bacteria. Bacteria can be shaped liked spheres, rods, commas, or spirals. The spherical bacteria are known as cocci. Rod shaped bacteria are known as bacilli. The bacteria that are shaped like commas are called vibrios. The spiral shaped bacteria are known as spirilli.
Recognize the difference between a Gram-positive bacteria and a Gram-negative bacteria after the gram stain has been applied. The Gram stain is used to differentiate between bacteria with a thick cell wall and bacteria with a thin cell wall. Gram-positive bacteria have a thick cell wall that is composed of peptidoglycan that is heavily cross-linked. The bacterium will show a purple stain. The Gram-negative bacteria have a think cell wall that is composed of peptidoglycan that is moderately cross-linked. The bacterium will show a pink stain.
Review the labs that will be on the lab practical. Before the exam, the professor will tell you which labs to study. Reread each of these labs, paying close attention to the details of the procedure.
Go to the microbiology lab and review the microscope slides you will have to identify. One of the main parts of a microbiology lab practical is being able to identify different microorganisms. As you examine the slides in the lab, take notes about distinguishing characteristics of each type of microorganism.
Review your notes regarding the chapters that correspond to the lab material. By reading the chapters, you will have a better understanding of the information in the lab. For example, you may have done a lab about the distinction between the gram-negative bacteria, such as Escherichia coli and Salmonella. In this case, it would help to review how Escerichia coli is a lactose fermenter, whereas Salmonella is not. The lactose fermenter will cause the pH indicator to change colors, which aids in the identification process.