Water Flashcards Preview

Bio - 2.1.2 Biological Molecules > Water > Flashcards

Flashcards in Water Deck (7)
Loading flashcards...
1
Q

Functions of water

A
  • Water is reactant in many chemical reactions such as hydrolysis.
  • It’s a polar molecule due to uneven distribution of charge.
  • Water is a solvent therefore substances can dissolve in it to form solutions where most biological reactions occur in.
  • It transports substances such as glucose and oxygen around plants and animals. This is due to strong cohesion.
  • It helps with minimising temperature fluctuations and thus acts as a buffer due to its high specific heat cap.
  • As it becomes less dense when frozen, ice floats to top and creates insulating layer. This increases the chance of survival of organisms in large bodies of water.
2
Q

Polarity of water

A
  • A molecule of water has one oxygen joined to two hydrogen atoms by shared electrons.
  • As the shared electrons are pulled more to the oxygen atom, the hydrogen atoms have a slightly positive charge and oxygen has a slightly negative charge.
  • This makes water a polar molecule.
3
Q

Hydrogen bonding in water

A
  • Hydrogen bonds are formed between the oxygen of one water molecule and the hydrogen of another.
  • Because of this, water molecules have an attraction for each other known as cohesion.
4
Q

High specific heat capacity and High latent heat of evaporation

A
  • Hydrogen bonds give water a high specific heat capacity.
  • Hydrogen bonds require more energy to break.
  • This means water doesn’t experience rapid temperature changes. Making it a good habitat.
5
Q

Very cohesive

A
  • Cohesion is the attraction between molecules of the same type.
  • Water molecules are very cohesive because they are polar.
  • This helps the water flow - making it good for transportation of substances. E.g up plant stems in transpiration.
6
Q

Low density when solid

A
  • Water molecules are further apart in ice because it is in a lattice shape making it less dense.
  • In cold temps ice forms an insulating layer on top of the water so the water below doesn’t freeze.
  • So organisms like fish can survive.
7
Q

Good solvent

A
  • Many important substances in reactions are ions.
  • Water is polar as the slightly positive end attracts anions and slightly neg end will attract cations.
  • This means ions will become surrounded by water molecules so they dissolve.
  • This is useful because water can transport dissolved substances such as in the blood.