Water plays a critical role in biological systems, serving various essential functions that are crucial for life. Here are some key roles and functions of water in biological systems:

1. Solvent
Water is often called the "universal solvent" because it can dissolve a wide variety of substances. This property is vital for:

Transport of Nutrients and Waste: Dissolved substances, including gases, nutrients, and waste products, can be transported within organisms.
Biochemical Reactions: Most biochemical reactions occur in aqueous environments. Water's ability to dissolve reactants and products is essential for metabolism.
2. Temperature Regulation
Water has a high specific heat capacity, meaning it can absorb and store large amounts of heat without a significant change in temperature. This property helps organisms:

Maintain Stable Internal Conditions: By buffering against rapid temperature changes.
Cool Down: Through processes like sweating and transpiration, where the evaporation of water from the surface of an organism removes heat.
3. Metabolism
Water is involved in numerous metabolic processes:

Hydrolysis Reactions: Water is used to break down complex molecules into simpler ones (e.g., during digestion).
Dehydration Synthesis: Water is released when small molecules are combined to form larger molecules (e.g., during the synthesis of proteins and nucleic acids).
4. Structural Function
Water contributes to the structural integrity of cells and tissues:

Cytoplasm: The cytoplasm of cells is primarily water, providing a medium for organelles and facilitating cellular processes.
Turgor Pressure: In plants, water within cells maintains turgor pressure, which keeps cells rigid and supports the plant structure.