Final answer:
Staining is necessary for cell observation under a light microscope due to the lack of natural color and contrast in cells, with stains and dyes used to enhance visibility and differentiate cellular structures.
Step-by-step explanation:
It is necessary to stain cells before observing them under the light microscope because most cells and microorganisms are naturally colorless and lack contrast, making it difficult to differentiate their structures. Utilization of stains and dyes adds colors, which enhance visibility and contrast, allowing for more detailed observation of cellular components. There are different types of stains, such as positive and negative stains, which interact differently with the specimen depending on chemical properties. Positive stains are absorbed by the cells, while negative stains outline the cells against a colored background. In addition to staining, techniques like phase-contrast microscopy aid in observing live specimens without staining, through enhanced contrast.