Water

Definition

Water is a simple chemical compound (H₂O) essential for all known forms of life. It acts as a solvent, regulates temperature, and facilitates various biological processes. Its unique properties, like high specific heat and cohesive behavior, make it vital for functions such as nutrient transport, cellular respiration, and maintaining homeostasis in organisms.

5 Must Know Facts For Your Next Test

1. Water makes up about 60% of the human body and plays a crucial role in maintaining cellular functions.
2. In osmosis, water moves to equalize solute concentrations on both sides of a membrane, which is critical for maintaining cell turgor pressure.
3. During glycolysis and the Krebs cycle, water is produced as a byproduct and is also used as a reactant in various metabolic pathways.
4. Water's high specific heat capacity allows it to absorb and release heat slowly, helping to stabilize temperatures in living organisms.
5. The electron transport chain relies on a gradient of protons across membranes, with water being formed when oxygen combines with these protons and electrons at the end of the chain.

Review Questions

• How does osmosis contribute to the overall health of cells, and what role does water play in this process?
  • Osmosis is essential for maintaining the proper balance of water and solutes in cells. When water moves through a semi-permeable membrane to equalize concentrations, it helps maintain cell turgor pressure, preventing cells from wilting or bursting. This process is crucial for nutrient absorption and waste removal, making water vital for cell health and function.
• Discuss how water is involved in cellular respiration, particularly in the glycolysis and Krebs cycle stages.
  • Water plays multiple roles in cellular respiration. In glycolysis, it helps in the breakdown of glucose into pyruvate. During the Krebs cycle, water molecules are also involved in reactions where acetyl-CoA combines with oxaloacetate to form citric acid. Additionally, water is produced at different steps as a byproduct, highlighting its importance as both a reactant and product in these energy-producing pathways.
• Evaluate the importance of water's properties in supporting life processes, especially concerning metabolic activities like cellular respiration.
  • Water's unique properties are fundamental for sustaining life. Its high specific heat allows organisms to maintain stable internal temperatures despite environmental changes, which is crucial during metabolic activities like cellular respiration. Furthermore, water's role as a solvent enables biochemical reactions by dissolving necessary substances, while its cohesive nature supports processes such as nutrient transport within organisms. Without these properties, metabolic processes would be severely hindered.

Related terms

Osmosis:

The process by which water molecules move across a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Metabolism:

The set of life-sustaining chemical reactions in organisms that convert food into energy and building blocks for growth, including cellular respiration where water is a byproduct.

Hydrophilic: Substances that have an affinity for water and can easily dissolve or interact with water molecules.