Water

• Water is a major component of cells and makes up 60-70% of the human body.
• Life evolved in an environment where water was abundant.
• Water is one of the most useful molecules in life, with its uses including being a reactant, providing structural support in cells and keeping organisms cool to maintain an optimum body temperature.
• Water molecules are made from one oxygen atom and two hydrogen atoms.
• Water is a polar molecule, as the oxygen atoms have a slight negative charge and the hydrogen atoms have a slight positive charge
• What atom in water has a slight negative charge?

  Oxygen
• What slight charge does oxygen have in water?

  Negative
• What atom in water has a slight positive charge?

  Hydrogen
• What slight charge does hydrogen have in water?

  Positive
• The polarity of water molecules means that a hydrogen atom on one water molecule is attracted to the oxygen atom on an adjacent water molecule, this attraction is called hydrogen bonding.
• What is hydrogen bonding?

  Attraction between a hydrogen atom and an electronegative atom (oxygen in water).
• Hydrogen bonding is weak when there are few of them, so they are constantly breaking and reforming, however, when there is a large number of them, they form a strong structure.
• Are hydrogen bonds weak?

  Yes when there are few of them, however, when there is a large number of them, they form a strong structure.
• Hydrogen bonds contribute to the many properties water molecules have that make them so important to living organisms.
• What type of force are hydrogen bonds?

  Intermolecular
• What is the main type of bonding in water molecules?

  Hydrogen bonding
• Water is a good metabolite
• Water is used or formed in many metabolic reactions, such as condensation and hydrolysis reactions, for example the hydrolysis of ATP, in which a bond is broken and a molecule of water is used up, making this a hydrolysis reaction.
• What is an example of water being used in a reaction?

  Hydrolysis reactions, such as the hydrolysis of ATP
• What is an example of water being formed in a reaction?

  Condensation reactions, such as ATP synthesis
• The regeneration of ATP involves water, as a new bond is formed and a water molecule is released, making this a condensation reaction.
• In hydrolysis reactions, one molecule of water is used.
• In condensation reactions, one molecule of water is released
• Specific heat capacity is the amount of thermal energy required to raise the temperature of 1kg of a substance by 1 degree
• What is specific heat capacity?

  The amount of heat energy required to raise the temperature of 1kg a substance by 1 degree.
• Water has a high specific heat capacity
• Water has a high specific heat capacity, meaning that a relatively large amount of energy is required to raise its temperature, this is due to the many hydrogen bonds present in water.
• Why does water have a high specific heat capacity?

  Many hydrogen bonds are present, and it takes a large amount of thermal energy to break and build them, therefore, the temperature of water does not fluctuate greatly.
• It takes a large amount of thermal energy to break and build the many hydrogen bonds in water, therefore meaning that its temperature does not fluctuate greatly.
• What is an advantage of water having a high specific heat capacity?

  Provides suitable habitats for sea life
• What is an advantage of water having a high specific heat capacity?

  Its able to maintain a constant temperature as water is able to absorb a lot of heat without big temperature changes, this is vital in maintaining temperatures that are optimal for enzyme activity.
• What is an advantage of water having a high specific heat capacity?

  As blood plasma passes through the more active and warmer regions of the body, heat energy is absorbed but the temperature remains fairly constant. Water in tissue fluid also plays an important regulatory role in maintaining a constant body temperature.
• Water in blood plasma is also vital in transferring heat around the body, helping to maintain a fairly constant temperature, for example, as blood passes through the more active, warmer regions of the body, heat energy is absorbed but the temperature remains fairly constant.
• Water has a high specific latent heat of vaporisation
• The specific latent heat of vaporisation is the amount of energy needed to change the state of 1kg of a substance from a liquid to a gas
• As liquid water heats up, hydrogen bonding makes it difficult to separate the water molecules from each other, this means that a lot of thermal energy is required to break the hydrogen bonds for water to evaporate.
• Why does water have a high latent heat of vaporisation?

  Hydrogen bonding makes it difficult to separate the water molecules from each other, this means that a lot of thermal energy is required to break the hydrogen for water to evaporate.
• How is having a high latent heat an advantage?

  Only little amounts of water are required to evaporate for the organism to lose a great amount of heat, providing a cooling effect for living organisms
• An example of high latent heat of water is transpiration from leaves or evaporation of water in sweat on skin
• Water is cohesive and adhesive, meaning it can stick to itself and other substances