Final answer:
Scientists mark bases on plates like agar plates to organize and differentiate sections for testing various substances or strains, an essential method for systematically studying and comparing microbial behavior.
Step-by-step explanation:
Bases are marked on scientists' plates, such as agar plates, in microbiology experiments to help differentiate and organize different sections or samples that are being tested. For example, in a Petri dish holding bacterial lawns, intersecting lines are drawn on the bottom of the dish to divide the plate into four sections. This organizational technique helps researchers keep track of different substances applied to the culture, such as antibiotics or growth factors. As Fleming's discovery of penicillin demonstrates, observing the effects of different substances on bacteria is crucial for developing medical treatments and understanding microbial behavior. Furthermore, plates are often labeled with pertinent information like the strain of bacteria or control markers to aid in the systematic study and comparison of results. This technique is also used in methods such as replica plating, which is a common technique to identify bacterial mutants by transferring cells from a master plate to secondary plates, each lacking a specific nutrient, to identify auxotrophic mutants. Lastly, labeling the agar plates helps maintain an organized structure in laboratories, which is imperative for the accuracy and reproducibility of scientific experiments