If a diploid cell is treated with colchicine, then it becomes

Explanation

To answer the question, "If a diploid cell is treated with colchicine, then it becomes," we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Colchicine**: Colchicine is a chemical that acts as a mitotic poison. It is known to disrupt the normal process of cell division.

2. **Effect on Microtubules**: Colchicine inhibits the formation of microtubules. Microtubules are essential components of the spindle apparatus that segregates chromosomes during cell division.

3. **Role of Spindle Fibers**: During mitosis, spindle fibers are responsible for the proper alignment and separation of chromosomes. Without these fibers, chromosomes cannot be distributed evenly to the daughter cells.

4. **Consequences of Colchicine Treatment**: When a diploid cell is treated with colchicine, the inability to form spindle fibers leads to a failure in chromosome segregation. As a result, the cell does not complete mitosis.

5. **Resulting Cell Condition**: The diploid cell, instead of dividing, ends up with double the number of chromosomes in a single cell. This condition is referred to as "tetraploid" (4n), as the cell has doubled its chromosome number from the original diploid (2n) state.

### Final Answer:
If a diploid cell is treated with colchicine, it becomes tetraploid (4n).