Which of the following statements is NOT true of mitosis?
The original cell produces two identical daughter cells.
It occurs at the same rate in all cells.
It follows duplication of DNA in the nucleus.
It involves the centrioles and a spindle.
The correct answer and explanation is :
The statement “It occurs at the same rate in all cells” is NOT true of mitosis.
Explanation:
Mitosis is a process of cell division that allows a single eukaryotic cell to divide and produce two genetically identical daughter cells. This process is crucial for growth, repair, and asexual reproduction in multicellular organisms.
Here’s a breakdown of why the statement “It occurs at the same rate in all cells” is incorrect:
- The original cell produces two identical daughter cells:
This statement is true. Mitosis ensures that the genetic material of the parent cell is duplicated and evenly distributed between two daughter cells, resulting in genetically identical offspring. This is vital for maintaining genetic consistency across cells within an organism. - It follows duplication of DNA in the nucleus:
This is also true. Before mitosis begins, the cell goes through the S-phase of the cell cycle, during which DNA replication occurs. This ensures that each daughter cell receives an exact copy of the genetic material. - It involves the centrioles and a spindle:
True as well. During mitosis, centrioles (in animal cells) help organize the spindle fibers that separate the chromosomes. The spindle fibers extend from the centrioles to align and pull apart the duplicated chromosomes, ensuring each daughter cell gets an identical set. - It occurs at the same rate in all cells:
This is NOT true. The rate of mitosis varies across different types of cells and different tissues in the body. For instance, cells in the skin, digestive tract, and bone marrow divide more frequently because these tissues undergo more wear and tear and require constant renewal. On the other hand, cells in organs like the brain or heart may divide much less frequently or not at all after reaching maturity. Factors like age, health, and environmental influences also play a role in regulating the rate of mitosis.
Thus, mitosis does not occur at the same rate in all cells, making this statement false.