Many biochemical reactions occur when there is a particular salt -blank- in the cells solution

Concentration  

Explanation - Biochemical reactions in a cell are catalyzed by enzymes. These enzymes increases the rate of reaction but themselves remain chemically unchanged. Enzymes or biological catalysts are very particular about the PH and salt concentration of the environment in which they are working.

They do not perform their function efficiently if the optimum PH is not maintained. Salts can be potassium based, sodium based, calcium based etc. Therefore, the activity of the enzyme in a biochemical reaction is highly regulated by the concentration of salt present.  

prophase: we can observe the chromosomes to coil up and condense. they become visible. nuclear membrane and envelope disintigrate.s

metaphase: chromosomes align at the center, the metaphase plate. spindle fibers attach to centromeres of the sister chromatids. they meet at kinetochores.

anaphase: sister chromatids are pulled towards each opposing centromere, set on different poles.

telophase: chromosomes are now clustered up only on either sides of the cell. nuclear membranes reform, and a new cell wall forms along the cell plate. this will lead to cytokinesis, the process that divides the cell membrane and forms the cell wall.