Water, Questions And Answers

Water
1. How are the properties of water important for its roles in living organisms?
Water is commonly called the universal solvent because it can dissolve more substances than any other liquid. The chemical composition of water means that it is effective as a solvent – water molecules have a polar arrangement which is due to the difference in electronegativity of oxygen and hydrogen. Since oxygen is highly electronegative it attracts the electron pairs in the covalent bonds to it, the oxygen atom becomes more electron dense. Because of this, the regions surrounding the hydrogen atoms become slightly ‘short’ of electrons and become δ+, whereas the oxygen becomes slightly negative (δ-). This allows water molecules to be attracted to many other types of molecules. Most substances that dissolve are ionic and when they are placed in water they dissociate into ions because the force of

The water molecules cluster around the substance and the ions are said to be hydrated. The solvent properties of water are crucial in water because it is used to transport biological molecules and a great deal of the biochemical reactions which occur will only do so when in an aqueous solution. Polar / ionic substances (such as acids, salts and alcohols) are soluble in water whereas nonpolar substances (such as fats and oils) aren’t.
Examples of the importance of water’s solvency are: necessary metabolites like minerals, amino acids and sugars dissolve in water; enzymatic reactions of photosynthesis and respiration take place in solution.
Plant specific examples: sugars such as glucose as well as amino acids are transported around plants in the phloem; the uptake of mineral ions across root hair cells from the soil occurs in solution; water and mineral ions move up the xylem in the transpiration stream;
An animal specific example: tissue fluid, blood plasma and cytoplasm, among others are water based.

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