LEHNINGER PRINCIPLES OF BIOCHEMISTRY - VOL. 1. THE FOUNDATIONS OF BIOCHEMISTRY: STRUCTURE AND CATALYSIS - 2011

PART I. STRUCTURE AND CATALYSIS

2. WATER

2.5. Living Organisms Are Adapted to the Aqueous Environment

Living organisms have successfully adapted to the aqueous environment and make use of its unusual properties. Because of its high specific heat capacity (the thermal energy required to raise the Temperature of 1 g of a substance by 1°C), Water acts as a "thermal buffer" within Cells, helping to maintain a relatively constant internal temperature despite fluctuations in ambient temperature and the heat generated during metabolic processes. In addition, the high heat of vaporization of water (Table 2-1) is utilized by some vertebrates to protect against overheating through the evaporation of sweat. The strong cohesion between molecules in liquid water, driven by intermolecular Hydrogen Bonds, facilitates the efficient transport of dissolved nutrients from roots to leaves in plants during Transpiration. Even the fact that ice has a lower density than liquid water is crucial for The life cycle of aquatic organisms. Freezing begins at The surface of bodies of water, and the resulting ice layer shields the underlying Water and Its inhabitants from frigid ambient air and complete freezing. However, the most critical factor for All living organisms is that many of the physical and biological properties of macromolecules, particularly Proteins and Nucleic Acids, depend on their interactions with water molecules. Water has profoundly and decisively shaped the course of biological evolution. If life exists elsewhere in the universe, it is unlikely to resemble Earth-based life unless that Location is as rich in liquid water as Earth.

Class="center">Numerous species of living organisms inhabit aquatic environments. Soft corals, Sponges, bryozoans, and Algae compete for space on this reef in the Philippines.