Final answer:
The statement that an isotonic solution is similar in concentration to blood is true. Isotonic solutions have the same osmolarity as blood, preventing net water movement across cell membranes. Hypertonic and hypotonic solutions can cause water to leave or enter cells, respectively.
Step-by-step explanation:
The term isotonic is used to describe a solution that has the same concentration of solutes as another solution, allowing for no net movement of water across a semi-permeable membrane. In the context of biological systems, when we say a solution is isotonic with respect to blood, we mean that the osmolarity of the solution matches that of the blood. Therefore, the statement that an isotonic solution is similar in concentration to blood is true.
When a cell is placed in an isotonic solution, there is no net movement of water into or out of the cell, although water molecules will still move back and forth across the membrane. In contrast, in a hypotonic solution, the extracellular fluid has a lower concentration of solutes compared to the inside of the cell, leading to water entering the cell. Conversely, in a hypertonic solution, the extracellular fluid has a higher concentration of solutes, causing water to leave the cell, potentially leading to cell shrinkage or collapse.