Final answer:
A red blood cell that develops abnormal notchings on its membrane due to water loss is known as a crenated cell, which occurs in a hypertonic solution.
Step-by-step explanation:
When a red blood cell develops abnormal notchings on its cell membrane due to the loss of water, it is described as a crenated cell. This condition occurs when the cell is in a hypertonic solution, where the concentration of solutes outside the cell is higher than inside, causing water to flow out of the cell. Consequently, the cell shrinks, leading to the characteristic crenation. In contrast, in an isotonic solution, a red blood cell will maintain its normal shape since the water exchange is balanced, while in a hypotonic solution, the cell may swell and potentially burst, a process known as hemolysis.