Final answer:
True, a streak for isolation is successful if there are single, isolated colonies in any zone on the plate. This allows for the selection of a single colony to create pure cultures, which is essential for microbiological studies.
Step-by-step explanation:
A streak for isolation, also known as Quadrant streaking, is indeed successful if it contains single, isolated colonies in any zone on the plate. This method, often used in microbiology, aims at separating a mixed culture into individual colonies. Each of these colonies originates from a single bacterial cell and is a clone of that cell. The presence of isolated colonies indicates that the bacteria have been sufficiently spread out over the surface of the agar plate to prevent the overgrowth of cells and facilitate the formation of pure cultures.
Different bacteria can give rise to colonies with distinct appearances, commonly referred to as colonial morphologies. When a streak plate is analyzed after incubation, finding well-separated colonies implies that the streaking method was effective and permits the selection of single colonies for further study. The ultimate goal is to create pure cultures from individual colonies, which can then be used in further microbiological analysis or applications.