Final answer:
Joshua is conducting a comparative study in cell biology to identify cellular structures and diversity using light microscopy, differentiating features between plant and animal cells while recognizing the importance of cell shape and growth patterns.
Step-by-step explanation:
Joshua's observation of various types of onion cells under a microscope to identify similarities and differences is a comparative study in cell biology. This type of investigation allows him to analyze cellular structures and understand cellular diversity. By using different forms of light microscopy, such as bright-field, phase-contrast, or fluorescence microscopy, Joshua can visualize the cells at high magnification and resolution, typically up to 1200X and 2 mm, respectively.
During his observation, Joshua might notice that plant cells, like onion cells, commonly have a rigid cell wall, a central vacuole, and chloroplasts, which are not present in animal cells. Conversely, both plant and animal cells share features such as a nucleus, cytoplasm, and cellular membranes. Identifying the shape and growth patterns of cells is crucial as it provides insight into the health and function of the cells. Moreover, other microscopy techniques such as electron microscopy could be used for more detailed study of the cellular structures.