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Water - Coggle Diagram
Water
Specific Latent Capacity of Water
Water molecules are cohesive, therefore it takes more energy to separate them.
This makes water a good buffer against sudden temperature changes.
Living organisms are mostly made of water. This water in and around our cells absorbs a lot for heat energy without its temperature increasing much.
This is an advantage for aquatic organisms as large bodies of water (seas or lakes) do not change temperature as quickly as terrestrial environments.
Latent Heat of Vaporisation of Water
Water absorbs a large amount of heat before it turns into water vapour. This is called the latent heat of vaporisation of water.
When molecules evaporate, their energy goes with them, which decreases the average kinetic energy of the water. This causes the water to cool down. The lost energy is known as latent heat of vaporisation.
This is important as water in sweat evaporates off the surface of the animal, which keeps the organism cool.
Plants are also cooled when water evaporates from their leaves (transpiration).
Cohesion and Surface Tension in Water
Cohesion in water is the property that makes water molecules attracted to one another.
Cohesion, due to the hydrogen bonds, creates surface tension on water.
It acts like a skin and is able to support small organisms. This allows small animals to live on the surface of water bodies.
Water moves up the xylem vessels as a continuous stream. Cohesion allows water to move from the roots to the top of the tallest trees.
Water and Hydrogen Bonding
Although each bond is fairly weak (about one-tenth as strong as a covalent bond), together they form important forces that cause the water molecules to stick together, giving water its unusual properties.
The attractive force between these opposite charges is
called a hydrogen bond.
The bond is formed due to the sharing of electrons between and oxygen.
The Dipolar Water Molecule
Although the molecule has no overall charge, the oxygen atom has a slight negative charge, while the hydrogen atoms have a slight positive one.
In other words. the water molecule has both positive and negative poles and is therefore described as dipolar.
The Importance of Water To Living Organisms
A Solvent
Water is polar. The slight positive and negative charges of water attract other molecules causing them to separate (dissolve) from each other.
When substances are dissolved in water, they are free to move around and react with other molecules.
This is important as metabolic reactions in living organisms can only happen when the reactants are dissolved in water.
Substances being dissolved in water, also allows then to be transported around the bodies of living organisms. For example . glucose, CO₂ and urea are transported in the blood plasma. Furthermore, mineral ions and sugars dissolved in water are transported in xylem and phloem in plants.
A Metabolite
Water molecules can also be involved in chemical reactions directly.
Condensation reactions are important in the synthesis of important molecules, such as proteins in living organisms.
Hydrolysis reactions are important in the digestion of large molecules in animals.