Biological Importance of Water
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Figure 2 Biological Importance of Water Water is of incredible biological importance and has several key properties to make it essential to life. The structure of water is known as ‘bent linear’; meaning that it has a V shape. The tip of the V is an oxygen atom which is very electronegative whereas the hydrogen atoms bonded to it are electropositive. The result of this is a ‘polar molecule’, where the tip of the oxygen end is delta (slightly) negative and the hydrogen ends are delta positive (Figure 1). The partial charges mean that water molecules interact in a generally attractive way - both towards each other (Figure 2) and to other materials. These properties are called cohesion and adhesion respectively. Both properties are needed for water to be pulled up the Xylem vessels in the plant stems in a continuous column by the Transpiration pull. Cohesion also causes surface tension, allowing objects that may be denser than water to float. This allows insects such as water striders to skate along the water’s surface. Water also has a very high specific heat capacity, meaning a large amount of energy is needed to heat up the water compared with other liquids. This causes water to resist temperature changes quickly which prevents the oceans from a sudden change in temperature, giving creatures enough time to either move or adapt. This property is also good for warm blooded creatures in a state of homeostasis as body temperature changes more slowly and sweat absorbs much more energy before evaporating. Water’s high specific heat capacity also gives it the largest temperature range of any substance in a liquid phase, providing an environment for aquatic organisms. This environment is maintained by the fact that ice is less dense than water and floats, providing an insulating layer that prevents the body of water freezing completely. Figure 1
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Biological Importance of Water
Transcript of Biological Importance of Water
Figure 2
Biological Importance of WaterWater is of incredible biological importance and has several key properties to make it essential to life.
The structure of water is known as ‘bent linear’; meaning that it has a V shape. The tip of the V is an oxygen atom which is very electronegative whereas the hydrogen atoms bonded to it are electropositive. The result of
this is a ‘polar molecule’, where the tip of the oxygen end is delta (slightly) negative and the hydrogen ends are delta positive (Figure 1). The partial charges mean that water molecules interact in a generally attractive way - both towards each other (Figure 2) and to other materials. These properties are called cohesion and adhesion respectively. Both properties are needed for water to be pulled up the Xylem vessels in the plant stems in a continuous column by the Transpiration pull. Cohesion also causes surface tension, allowing objects that may be denser than water to float. This
allows insects such as water striders to skate along the water’s surface.
Water also has a very high specific heat capacity, meaning a large amount of energy is needed to heat up the water compared with other liquids. This causes water to resist temperature changes quickly which prevents the oceans from a sudden change in temperature, giving creatures enough time to either move or adapt. This property is also good for warm blooded creatures in a state of homeostasis as body temperature changes more slowly and sweat absorbs much more energy before evaporating. Water’s high specific heat capacity also gives it the largest temperature range of any substance in a liquid phase, providing an environment for aquatic organisms. This environment is maintained by the fact that ice is less dense than water and floats, providing an insulating layer that prevents the body of water freezing completely.
Water is also an incredibly good solvent and all ionic substances can be dissolved in it. The reason is that water is a polar molecule and ions on the edge of an ionic lattice, from which ionic substances are made, are attracted to many water molecules’ poles and can be pulled away from the lattice into solution (Figure 3). Other polar molecules also dissolve in water such as sugar. This means water is able to provide the solvent in which nearly all chemical reactions in biology take place. This also allows organisms to carry mineral ions in solution. E.g. Magnesium in blood.
Figure 1
Figure 3
