BIOL 1001 Chapter Notes - Chapter 2: Surface Tension, Formaldehyde, Sodium Hydroxide
Document Summary
Water makes up 60-90% body weight of most organisms. Water molecules attract one another: cohesion, hydrogen bonding between water molecules produces high cohesion. The molecules of a substance tend to stick together: water cohesion explains how water molecules can form a chain in delivering moisture to the top of a tree (r- below- fig. 2. 8: cohesion of water molecules along a surface produces surface tension, spiders and water striders rely on surface tension to move across the surface of ponds (l- below) Water molecules stick to polar or charged surfaces according to the property called adhesion: adhesion helps water climb up the thin tubes of plants to the leaves. Water soluble molecules are hydrophillic: ex. - sugars and amino acids. Fat and oils water-based solutions can be acidic, basic or neutral. A small fraction of water molecules break apart into ions (fig. Lemon juice and vinegar are naturally occurring acids.
