Water
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Explain how hydrogen bonds form between water molecules.
Hydrogen bonds form due to the slight negative charge (δ-) on the oxygen atom and slight positive charge (δ+) on the hydrogen atoms within a water molecule. This polarity arises from oxygen's higher electronegativity. The δ+ hydrogen of one water molecule is attracted to the δ- oxygen of another, forming a hydrogen bond.
Define the term 'solvent' and explain why water is an effective solvent.
A solvent is a substance that dissolves a solute, resulting in a solution. Water is an excellent solvent due to its polarity, which allows it to form hydrogen bonds with, and thus dissolve, many polar and ionic substances such as glucose and salts.
Explain how water's solvent properties are important in living organisms.
Water's solvent properties allow for the transport of essential substances (
Define 'specific heat capacity' and explain why water has a high specific heat capacity.
Specific heat capacity is the amount of heat energy required to raise the temperature of 1 gram of a substance by 1 degree Celsius. Water has a high specific heat capacity because hydrogen bonds between water molecules require a lot of energy to break or weaken, limiting temperature increases.
Explain the biological significance of water's high specific heat capacity.
Water's high specific heat capacity helps maintain stable internal temperatures in organisms and aquatic environments. This prevents rapid temperature fluctuations that could harm biological processes.
Define 'latent heat of vaporisation' and explain why water has a high latent heat of vaporisation.
Latent heat of vaporisation is the amount of heat energy required to change 1 gram of a liquid into a gas at its boiling point. Water has a high latent heat of vaporisation due to the strong hydrogen bonds that must be broken to allow water molecules to escape as gas.
Explain how water's high latent heat of vaporisation is important for thermoregulation in living organisms.
Evaporation of water, such as sweat in mammals or transpiration in plants, requires a large amount of heat energy. This cools the organism as the heat is taken away from the body, providing an effective cooling mechanism.
Describe an example of how water's properties contribute to the transport of nutrients in plants.
Water acts as a solvent to dissolve mineral ions in the soil, which are then transported up the xylem vessels from the roots to the leaves through transpiration. Water's cohesive properties, due to hydrogen bonding, allow for the continuous water column needed for transpiration.
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