Water

• What is the structure of water?

  2 H atoms and one O atom share electrons to covalently bond,
• How is the delta positive of the hydrogen atoms formed and the delta negative of the oxygen atom formed?

  because the shared negative hydrogen electrons are pulled toward the oxygen atom the other side of each hydrogen atom is left with a slight positive charge, the unshared negative electrons from the Oxygen atom give it a slight negative charge
• What does the delta positive and delta negative charges on each side of the water molecule mean?

  it is a polar molecule
• What bonds form between 2 water molecules

  hydrogen bonds
• How are the hydrogen bonds formed between water molecules?

  The delta negative oxygen atoms attractive delta positive hydrogen atoms of another water molecule.
• What are 5 properties of water?

  Metabolite

  High latent heat of vaporisation

  Buffers temperature changes

  Good solvent

  Strong cohesion
• What is it important that water is a metabolite?

  many metabolic reactions are condensation or hydrolysis so release or require water.
• What does it mean that water has a high latent heat of vaporisation, and why is this important?

  - it means it takes a long of energy to break the hydrogen bonds between water molecules, so lots of energy is used yo when water evaporates.

  - this is useful as organisms can use water loss through evaporation to cool down without loosing too much water (lost of energy/heat is released to vaporise small amounts of water)
• Why can water buffer temperature change and why is this important?

  - the hydrogen bonds between molecules can absorb lots of energy, so water has a high specific heat capacity

  - this means water doesn't experience rapid temperature changes so is a good habitat as the temperature under water is more stable than on land

  - this also means water inside organisms remains a fairly stable temperature- maintain constant internal body temperature.
• How is water a solvent, and why is this useful?

  - A lot of important substances in biological reactions are ionic

  - Water is polar so the positive end will be attracted to a negative ion and the negative end will be attracted to a positive ion

  - the ions will become totally surrounded by the water molecules so will dissolve.

  - this is important as many metabolic reactions happen in solution.
• What does it mean that water is cohesive and what uses does this create?

  - water molecules attract to each other snd 'stick' together due to their polarity

  - this helps water flow making it good for transporting substances eg water travels in columns up the xylem

  - also creates high surface tension when it comes into contact with air.