Final answer:
Chris puts a coverslip on top of the slide after staining the onion cells with iodine.
Step-by-step explanation:
After staining the onion cells with iodine, a coverslip is placed on top of the slide to create a thin, flat layer, securing the stained cells for observation under a microscope. The coverslip serves several essential purposes in microscopy. Firstly, it helps protect the specimen from drying out by minimizing air exposure. Additionally, it flattens the specimen, allowing for a clearer view and preventing distortion. The coverslip also facilitates the application of an immersion oil if using an oil immersion objective for higher magnification.
Using a coverslip ensures that the stained onion cells remain in their original orientation and arrangement, enhancing the quality of microscopic examination. It is a standard practice in microscopy to cover stained specimens with a coverslip to optimize imaging conditions and preserve the integrity of the sample.
Placing a coverslip on the iodine-stained onion cells slide is a crucial step in microscopy, providing optimal conditions for observation and preserving the specimen for accurate analysis.