2 Molecular biology – 2.2 Water
http://www.bioknowledgy.info/ (Chris Paine)
2.2 Water - the bottom line
The learning Statements
The can you statements tell you what you notes should enable you to do. They are guidance to a minimum
expectation. The deeper your understanding the easier you will find it to respond to questions and
communicate your understanding.
2.2.U1 Water molecules are polar and hydrogen bonds form between them.
Can you distinguish between covalent, ionic and hydrogen bonds?
Can you draw and label a diagram of the atomic structure of a water molecule, including the polarity of the
molecule and the position of the electrons in the outer shell?
Can you, with reference to the diagram, explain why water is a polar molecule?
Can you show the formation of hydrogen bonds between water molecules in a annotated diagram?
2.2.U2 Hydrogen bonding and dipolarity explain the cohesive, adhesive, thermal and solvent properties of
Can you distinguish between adhesion with cohesion?
Can you outline an example of how cohesion benefits an organism?
Can you outline an example of how adhesion benefits an organism?
Can you explain why water is a very good solvent?
Can you outline examples of how the solvent properties of water benefits organisms?
Can you state the three thermal properties of water that are useful to organisms and explain, using an
example, their usefulness to organisms?
2.2.A2 Use of water as a coolant in sweat.
Can you give a reason why it is important for mammals to control their body temperature?
Can you explain how sweating is used as a mechanism to cool the body?
Nature of science: Use theories to explain natural phenomena - the theory that hydrogen bonds form
between water molecules explains the properties of water. (2.2)
Can you explain how the observable properties of water provide evidence to support, and therefore are in
turn explained by, the theory of hydrogen bonding?
2.2.U3 Substances can be hydrophilic or hydrophobic.
Can you state that polar and ionic molecules are hydrophilic and non-polar, non-ionic molecules are
Can you outline the link between hydrophilic molecules and the solvent and adhesive properties of water?
Can give examples of hydrophobic molecules and a solvent they can dissolve into?
2.2.A3 Modes of transport of glucose, amino acids, cholesterol, fats. oxygen, and sodium in blood in
relations to their solubility in water.
Can you identify glucose, amino acids, cholesterol, fats, oxygen, and sodium chloride. molecules as either
being hydrophobic or hydrophilic?
Can you outline the mechanism of transport in the blood of glucose, amino acids, cholesterol, fats, oxygen,
and sodium chloride?
2.2.A1 Comparison of the thermal properties of water with those of methane.
Can you compare and contrast the physical properties of methane and water (apart from molecular mass
and formula values you need not recall the values)?
Can you explain why the physical water and methane are different given their similar molecular mass?