Which phase of mitosis is shown at the
letter ‘A’?
A Interphase
B Prophase
C Metaphase
D Anaphase
E Telophase
The Correct answer and Explanation is:
To identify which phase of mitosis is indicated by the letter ‘A’, it’s essential to understand the distinct characteristics of each phase in the cell cycle, particularly during mitosis.
Answer: B. Prophase
Explanation:
Mitosis is the process by which a cell divides to produce two identical daughter cells, and it consists of several key phases: prophase, metaphase, anaphase, and telophase. Each phase has unique visual and functional characteristics observable under a microscope.
- Interphase (A) is technically not a part of mitosis but the phase where the cell spends the majority of its life cycle preparing for mitosis. During interphase, the cell grows, replicates its DNA, and prepares the necessary components for cell division. The chromatin is decondensed, making it less visible.
- Prophase (B), the first stage of mitosis, is characterized by the condensation of chromatin into visible chromosomes. Each chromosome consists of two sister chromatids connected at a centromere. The nuclear envelope begins to break down, and the mitotic spindle, which is formed from microtubules, starts to form from the centrosomes that migrate to opposite poles of the cell. This stage can be recognized by the presence of clearly defined chromosomes and the disintegration of the nuclear envelope.
- Metaphase (C) follows prophase, where the chromosomes align along the metaphase plate (the cell’s equatorial plane), and the spindle fibers attach to the centromeres of the chromosomes.
- Anaphase (D) is marked by the separation of sister chromatids, pulling them toward opposite poles of the cell.
- Telophase (E) is the final stage of mitosis, characterized by the reformation of the nuclear envelope around each set of separated chromatids, which begin to decondense back into chromatin.
Given these characteristics, if the letter ‘A’ refers to a phase showing condensed chromosomes and a breaking down nuclear envelope, it would clearly indicate prophase, confirming the answer as B. Prophase.