Biological molecules

• What properties give water a biological significance?

  low density when frozen

  high specific heat capacity

  high latent heat of vapourisation

  surface tension

  used as a solvent

  adhesion and cohesion
• What are disaccharides?

  sugars with 2 chains of hexoses

  formed by the condensation reaction of 2 monossacharidea bonded by a glycosidic bond
• What are monosaccharides (+ examples and their properties)?

  A simple sugar with 1 chain of 3,5 or 6 carbon atoms

  Glucose, Ribose, Frutose

  Sweet, Soluble, Crystalline
• What is cohesion?


  Is where ‘like‘ molecules stick together

  for example water molecules sticking together
• What is the biological significance of cohesion?

  Cohesion allows long columns of water to travel in the xylem tubes

  Cohesion causes surface tension where water meets air, which creates a habitat on the surface for water for pond skaters
• What is adhesion?

  The ability for dissimilar molecules to stick together as a result of the hydrogen bonds
• Why is adhesion useful?

  In the xylem- water molecules are attracted to the cells in the xylem wall allowing water to travel up
• What is an isomer?

  Isomers are molecules with the same molecular formula but different structural arrangement of atoms

  for example- Alpha and Beta glucose
• What happens during dissacharide bonding?

  A condensation reaction occurs. Water is eliminated (released) and a glycosidic bond is formed
• What are polysaccharides?

  Chains of monosaccharides

  Macromolecules with many chains of 6 carbon atoms, joined by glycosidic bonds
• Give 5 examples of polyssacharides?

  Starch

  Cellulose

  Glycogen

  Chitin

  Peptidoglycan
• What is a condensation reaction?


  The formation of two molecules together with the formation of a chemical bond and involves the elimination of a molecule of water
• Why does water have a high specific heat capacity?

  Large amounts of energy is needed to change the temperature of water by 1 degree Celsius. Because heat energy will go towards breaking the hydrogen bonds in water rather than increasing the kinetic energy in the water molecules.
• How is waters high SHC biologically significant?

  Acts as a buffer against rapid temperature fluctuations.

  Good for regulations in large bodies of water, in habitats for aquatic organisms. for example coral reef.

  Essential In thermoregulation- regulating temps in endothermic organisms for optimal enzyme activity
• Why is waters high latent heat of vaporisation biologically significant?

  Means large amounts of energy is needed to evaporate water

  Allows organisms to cool off without losing too much water. for example sweating (heat transfer)
• How is the density of water biologically significant?

  Waters density is lower when frozen(in a solid state)- ice

  Means ice can float on top of water creating a habitat for organisms above.

  Ice insulates water below to prevent it from freezing, maintaining habitat for aquatic organisms below ice
• Why does water have a lower density when frozen?

  When frozen ice molecules from more hydrogen bonds between them, that being 4 (the maximum amount). This increases space between molecules (held further apart) making it less dense.