A strange new bacterial cell is discovered by your research team near sulfur vents in the ocean. This new bacteria seems to be lacking any proteins in its cell membrane. When you take it out of its environment, it begins to die because it needs Calcium ions, Ca+. If the concentration inside the bacteria is 100 ppm, what concentration of Ca + in the solution outside the bacteria would keep it alive? A. 75 B. 100 C. None of these D. 125

Answer: Option B; 100

Explanation: If the cell is placed in a solution with 75 ppm calcium ions, then the cell will die, because water will enter the cells and they can burst. 75 ppm is quite a hypotonic solution for survival of bacterial cells. Same is the case will 125 ppm, here the cells will die because of dehydration. The increased solute concentration will make the bacterial cells to loose water and this principle is used in preservation.

100 ppm will provide the most stable environment because the water movement will occur at a same rate and the processes of the cell can proceed at required rate.

Option D, 125

Explanation:

It is given that the bacterial cell require calcium ion to survive. The inner concentration of calcium with in this organism is 100 ppm. Thus, in order to gain more calcium ion, this cell must be placed in a concentration where calcium ions concentration is higher as compared to the inner concentration. Thus, option D is correct because when the bacterial cell is placed in a concentration of 125 ppm, the outer concentration gets higher than the inner concentration and therefore the calcium ions will flow from high concentration to low concentration area.