Water And Its Functions Flashcards
Why does water have a dipole?
The oxygen carries a small negative charge
The hydrogen carries a small positive charge
Why do hydrophilic substances dissolve in water?
They readily form hydrogen bonds with water molecules.
What role does water play in metabolic reactions?
Water is a metabolite in many metabolic reactions, including hydrolysis and condensation reactions.
What are non-polar molecules in relation to water?
Non-polar molecules are hydrophobic and do not dissolve in water.
What does it mean for a substance to be hydrophobic?
Hydrophobic substances are insoluble in water.
Solutes (which dissolve in water) are said to be…
Hydrophilic because they readily dissolve in water
What bond forms between the O and H in water
Hydrogen bonds
What is high specific heat capacity?
It requires a lot of energy to raise the temperature of water because molecules stick together due to hydrogen bonding.
Why is the boiling point of water higher than expected?
The boiling point of water is higher than expected due to hydrogen bonding; without it, water would be a gas at room temperature.
Why is high specific heat capacity useful?
It creates a stable environment to live in.
Importance of high specific heat capacity in water
-maintains relatively constant temperature
-organisms living in aquatic environments don’t experience large fluctuations of temp
Why does water have a high latent heat of evaporisation
Takes a lot of energy to change it from a liquid to a gas
High latent heat of evaporisation importance in water
-good coolant( when we sweat the water uses heat energy from our body to evaporate therefore cooling us down
What is useful about water have cohesion
Cohesion allows a column of water to be pulled up through xylem vessels in plants from the roots to the top
What is useful about water have surface tension
The hydrogen bonds between neighbouring water molecules cause a ‘film’ to develop at the surface which can support small organisms such as pond skaters
Why is water important in metabolic reactions?
-water is used in the break down of complex molecules (eg polysaccharides and monosaccharides) by hydrolysis and is produced in condensation reactions
-metabolic reactions take place in an aqueous medium
-water is used in photosynthesis and is released in respiration
Why is water used as a solvent?
-More substances will dissolve in water than any other liquid
-non polar molecules such as lipids will NOT dissolve
Ions attract water molecules…
…then the water molecule ‘encases’ them
What is the importance of water being a solvent
-blood plasma mostly consists of water and transports dissolved substances such as glucose
-the cytoplasm in cells contain high percentage of water many chemical reactions take place here
-plants transport solution in the xylem and phloem
Describe the structure and bonding of water
Water molecules form a lattice held by hydrogen bonds. This means that the water molecules are closest at 4 degrees c and this is when water is most dense
Importance
Maximum density at 4 degrees c provides up thrust to support aquatic organisms eg whales
The importance of ice
-Ice floats on the surface of water which insulates large bodies of water from further heat loss and the bottom of the body of water remains as a liquid allowing life to continue
The importance of water being transparent
-light can penetrate so plants can photosynthesise
-light rays can pass through the jelly like vitreous humour fluid in the eye and reach the retina
Importance of water not being easily compressed
-provides support and maintains shape and structure of some organisms
-the hydrostatic skeleton in the earthworm
-turgor pressure in plants
Why is water a liquid at normal temperatures and pressures? And what is its biological significance?
Hydrogen bonds form between water molecules keep the molecules close enough together so that is a liquid
Water can be used as a medium for mass transport. Small molecules and ions can move by diffusion
