Question

Mitotic poison is
A. Nitrate
B. carbon dioxide
C. Colchicine
D. Trehalose

Answer 1

Hint: Mitotic poisons are those substances/chemicals which inhibit the m-phase.

Complete Answer:
- Every mitotic poison has its activity at different phases of the m phase of the cell cycle. Colchicine is one of the mitotic/spindle poison which inhibits the formation of metaphase plates. It is derived from colchicine autumnale belonging to the liliaceae family of monocotyledonae class.
- It does not allow cells to divide so DNA and chromosomes replicate but due to absence of division these cells increase in number, and number of chromosomes set increase,resulting in polyploidy.
- X Rays are known for breaking the chromosomes as they react with DNA present in them and cause mutations that can be very harmful.
- Azides and cyanides are one of them. Enzyme ribonuclease acts at prophase stage. Mustard gas causes agglutination of chromosome material and is the effective mitotic poison.
- Due to their activity mitosis does not continue further and cells remain arrested at particular phase because they lost their ability to divide as there is no stimulus

Hence the correct answer is option C.

Note: There are many of the spindle poisons like carbon monoxide which inhibit cytochrome oxidase enzyme thereby not allowing the process of respiration to occur.