Water

Definition

Water is a chemical compound consisting of two hydrogen atoms bonded to one oxygen atom, forming the essential substance for all forms of life. It plays a crucial role in various biological processes, serving as a solvent, temperature regulator, and participant in biochemical reactions. Water's unique properties, such as cohesion, adhesion, and its ability to dissolve many substances, make it indispensable for maintaining homeostasis in living organisms.

5 Must Know Facts For Your Next Test

1. Water covers about 71% of the Earth's surface and is vital for all known forms of life.
2. It has a high specific heat capacity, meaning it can absorb and release large amounts of heat without drastically changing temperature, which helps regulate climate.
3. Water is a solvent for many ionic and polar substances due to its polar nature, allowing for essential biochemical reactions.
4. The structure of water molecules leads to cohesion (attraction between like molecules) and adhesion (attraction between unlike molecules), facilitating processes like capillary action in plants.
5. Ice floats on water because it is less dense than liquid water, providing insulation to aquatic ecosystems during cold weather.

Review Questions

• How do the properties of water contribute to its role as a solvent in biological systems?
  • The properties of water, particularly its polarity and ability to form hydrogen bonds, make it an excellent solvent for many substances. When ionic or polar compounds enter water, the positive and negative regions of water molecules surround the solute particles, facilitating their dissociation. This allows water to carry essential nutrients, ions, and waste products in biological systems, making it vital for cellular functions.
• Evaluate how water's high specific heat capacity impacts temperature regulation in living organisms.
  • Water's high specific heat capacity allows it to absorb significant amounts of heat without experiencing drastic temperature changes. This property helps stabilize internal temperatures within organisms, preventing overheating during metabolic processes. Furthermore, it plays a crucial role in regulating the climate by moderating temperature fluctuations in aquatic environments and influencing weather patterns.
• Assess the implications of ice being less dense than liquid water for aquatic life during winter months.
  • Ice's lower density than liquid water leads to its formation on the surface of bodies of water during cold months. This insulating layer prevents deeper waters from freezing completely, allowing aquatic life to survive beneath the ice. The unique behavior of water not only supports various ecosystems but also affects global climate patterns by influencing heat distribution in large bodies of water.

Related terms

hydrogen bond:

A weak bond formed between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

polar molecule:

A molecule with an uneven distribution of charge, leading to a partial positive charge on one side and a partial negative charge on the other.

solute: A substance that is dissolved in a solution, which in biological contexts often involves water as the solvent.