Statement I: Red blood cells burst when placed in water. Statement II: Due to the phenomenon of osmosis, water enters into red bloood cells.

Red blood cells (RBCs) lack a rigid cell wall, making them susceptible to volume changes based on the tonicity of their environment [3]. When placed in distilled water, which is a hypotonic solution, a concentration gradient is established between the cell's interior and the exterior [2]. Through the process of osmosis, water molecules move across the selectively permeable cell membrane into the RBC, where the solute concentration is higher [6]. This influx of water causes the cell to swell. Because the plasma membrane has a limited capacity for expansion, the internal osmotic pressure eventually exceeds the membrane's structural integrity, leading to the cell bursting, a phenomenon known as haemolysis or cytolysis [3]. Thus, Statement I is true, and Statement II correctly explains the mechanism behind it.

Sources

1. [3] https://en.wikipedia.org/wiki/Cytolysis
2. [1] https://research-information.bris.ac.uk/en/publications/measuring-osmosis-and-hemolysis-of-red-blood-cells/
3. [2] https://www.ncbi.nlm.nih.gov/books/NBK541095/
4. [6] https://pmc.ncbi.nlm.nih.gov/articles/PMC6008142/