Question

If you are provided with root tips of onion in your class and are asked to count the chromosomes, which of the following stages can be most conveniently looked into ?

• A. Metaphase
• B. Telophase
• C. Anaphase
• D. Prophase

Answer 1

The Correct Option is A

To determine which stage of cell division is most suitable for counting chromosomes in onion root tips, we need to understand the process of mitosis and the characteristics of its stages:

1. Prophase: During this initial stage, chromosomes condense and become visible under the microscope. However, they are not yet aligned or organized optimally for counting as they are still diffused.
2. Metaphase: In this stage, chromosomes align at the cell's equatorial plate, and their centromeres attach to spindle fibers. This alignment makes it an ideal stage for counting chromosomes as they are highly condensed and organized in a single plane.
3. Anaphase: Chromosomes are split and pulled towards opposite poles of the cell. While chromosomes become very visible, they are separating, which makes accurate counting difficult as they move away from the center.
4. Telophase: Chromosomes reach the poles and begin to de-condense, making them less distinct. This stage is unsuitable for counting due to reduced visibility and clarity of individual chromosomes.

Based on these descriptions, the correct stage for counting chromosomes is Metaphase. At this stage, chromosomes are maximally condensed and aligned at the cell's equator, allowing for clear visibility and easier counting.

Therefore, the correct answer is:

1. Metaphase

This is because chromosomes are best observed and counted when they are fully condensed and aligned during metaphase.