Water

Question 1

Where the hydrogen bonds form between water molecules ?

Answer 1

oxygen of one water molecule to the hydrogen atom of another

Question 2

Water is a Polar Molecule?

Answer 2

• O is more electronegative than H is slightly positive
• O attracts electrons more strongly, (δ-) and a weak positively charged region on the hydrogen atoms(δ+),
• uneven distribution of charge
• One atom of oxygen combines with two atoms of hydrogen by sharing electrons (covalent bonding)

Question 3

what is water ?

Answer 3

• A metabolie used in hydrolysis and made in condensation reactions
• Metabolites can be transported efficiently (except non-polar molecules which are hydrophobic)

Question 4

what is dipole?

Answer 4

• separation of charge due to the electrons in the covalent bonds being unevenly shared.

Question 5

An excellent solvent

• What is its role in Living organisms and why?

Answer 5

– many substances can dissolve in water
- Allows chemical reactions to occur
- Transports mediums
= due to the polarity of water molecules

Question 6

Water is a polar molecule many ions (e.g. sodium chloride) and covalently bonded polar substances (e.g. glucose). What does this allow, and why?

Answer 6

• This allows chemical reactions to occur within cells
• as the dissolved solutes are more chemically reactive when they are free to move about)

Question 7

The high specific heat capacity is due to the many hydrogen bonds present in water. It takes a lot of thermal energy to break these bonds and a lot of energy to raise temperature of water does not fluctuate greatly for optimal enzyme activity .

• What is its role in Living organisms and why?

Answer 7

• A relatively high specific heat capacity
• Allows water to be a suitable habitat
• Optimal temperature is remained between cells and bodies
• Water in tissue fluid also plays an important regulatory role in maintaining a constant body temperature
  = Due to the presence of many hydrogen bond

Question 8

Latent heat of vaporisation (in order to change state (from liquid to gas) a large amount of thermal energy must be absorbed by water to break the hydrogen bonds and evaporate)

• What is its role in Living organisms and why?

Answer 8

• Water is less dense when a solid
• little water is required to evaporate for the organism to lose a great amount of heat
• Water has high surface tension and cohesion
  It acts as a reagent
• Coolant e.g the transpiration from leaves or evaporation of water in sweat on the skin
  = due to the presence of many H bonds

Question 9

Cohesion

Answer 9

• is where the tension of H20 molecules in transpiration stream and strong cohesion supports column of water = the surface tension in water causes an air boundary.

Question 10

biological important properties of H2O:

Answer 10

• due to polarity and intermolecular H-bonds
• Metabolise (condensation and hydrolysis used for making and breaking bonds) / solvent for chemistry reactions in body (allow gases to readily diffuse and enzyme and waste e.g ammonia)
• high SHC ( because O&H molecules stick = high energy to minimise temp fluctuations - act as buffer)
• high latent heat of vap H bonds evaporate 1 gram = loss of energy
• cohesion between molecules

Question 11

Water for organisms ?

Answer 11

• due to the polar mol during metabolic reactions
• Enables organism to avoid fluctuations in core temp
• Cohesion supports columns of water