Question

A student is looking at a slide to find cells in different stages of mitosis. she uses the slides that contain slices of the onion root where cells are actively dividing. why is it important to use the onion roots to observe chromosomes during mitosis rather than a cell from another part of the plant?

a. because cells in the leaves divide, but they do not use mitosis
b. because chromosomes only form during mitosis, a part of cell division
c. because other cells in the plant to do not have dna or chromosomes.
d. because root cells are naturally stained, so chromosomes show up easier

Answer 1

The direct answer to why an onion root is used to observe mitosis is because chromosomes only form during mitosis. Onion roots have a high cell division rate, and the root tip's dividing cells make it easier to view chromosomes. Staining increases visibility of chromosomes, which helps in studying the mitotic stages.

Step-by-step explanation:

The onion root is commonly used to observe chromosomes during mitosis because of its high rate of cell division, particularly in the root tip where cells are actively dividing. The correct answer to the student's question is option B: because chromosomes only form during mitosis, a part of cell division.

Chromosomes are not always visible in non-dividing cells because the DNA is not condensed into chromosomes. However, during mitosis, the DNA in the cell's nucleus condenses to form visible chromosomes. This condensation makes it easier to observe the processes involved in genetic separation and distribution to daughter cells.

The onion root is an ideal location for this type of observation because it contains a large number of cells in various stages of the cell cycle. Other parts of a plant also undergo mitosis, but the root tip, known for its robust meristematic (dividing) cells, provides a greater chance to view the different stages. Moreover, when stained appropriately, chromosomes in the root cells become even more visible under a microscope, facilitating an easier and more effective study of mitotic stages.