Question

A student prepared a stained squash of cells from the tip of an onion root and observed it using an optical microscope. During the preparation of the slide, he:

Why did the student use only the first 5 mm from the tip of an onion root?
a) To maximize the number of cells for observation
b) To ensure the cells were in the G1 phase
c) To speed up the staining process
d) To study mature cells

Answer 1

The technician observing onion root cells stained for mitosis would expect to see different stages of cell division. Stains are crucial for microscope slide preparation as they enhance visibility of cellular structures, with some stains being specific for certain cell components, like lignin in xylem cells.

Step-by-step explanation:

The procedure of preparing a stained squash of cells, such as those from the tip of an onion root, involves staining to enhance the contrast under an optical microscope. When observing these cells, the technician would expect to see the different stages of mitosis. This is particularly relevant to a rapidly dividing area of the plant like the root tip. The student may notice cells in interphase, prophase, metaphase, anaphase, and telophase when comparing sections from various areas of the root.

Stains and dyes are essential in microscopy to help differentiate and observe cellular structures that would otherwise be difficult to see. Different types of cells will take up specific stains differently. For instance, when observing a stem section stained for lignin, cells with thickened walls and large hollow centers, such as those in xylem, will be preferentially stained. This aids in identifying the type of cell and its structure or composition under the microscope.

In general, microscope slides are prepared by mounting and fixing cells onto a glass slide, followed by the application of dyes, and viewed under various types of microscopes appropriate to the staining technique used.