2.2 Flashcards
Water is often called a universal solvent. Explain how this is a benefit to life:
Metabolism: cytoplasm of cells is mostly water & the chemical reactions of metabolism take place there
Transport: substances can be transported around the body dissolved in blood plasma
or
around plants dissolved in the water in the xylem vessels
Name the properties of water and name the benefits they have to living organisms:
Cohesive - water molecules attracted to each other
it gives water high surface tension, so small insects can walk on its surface & cohesion helps prevent columns of water of xylem vessels from breaking
Adhesion - water molecules being attracted to other molecules
water adheres to cellulose in plant cell walls, this helps it stick to the sides of xylem vessels & to move out of top of xylem and into leaf cells
High Specific heat capacity - takes a lot of heat to raise water temp
water temp remains stable, so it’s a thermally stable habitat for aquatic animals
High Latent heat of vapourisation - takes a lot of energy to overcome H-bonds for water to become a vapour
Means water is a good coolant;
sweating - evaporation of water from skin takes heat away from the body
transpiration - water evaporating from leaves cools it down
High boiling point
good because cells of living organisms contain a high proportion of liquid water
Compare the thermal properties of water with those of methane:
Water had higher, density, LHV, boiling & melting point, specific heat capacity
What makes a substance hydrophilic?
When molecules have a partial or whole charge because they are attracted to polar molecules
What makes a substance hydrophobic?
A molecule that is non-polar or not charged and therefore insoluble
What is the mode of transport of sodium chloride in relation to irs solubility in water?
It’s transported in blood in the form of Na+ and Cl- ions
The ions are easily dissolved in water
What is the mode of transport of amino acids in relation to its solubility in water?
Acids w/ hydrophilic R-group are easily dissolved in water & transported in the blood
Acids w/ hydrophobic R-group aren’t easily dissolved in water & will be transported in lower concentrations in blood
What is the mode of transport of glucose in relation to its solubility in water?
It’s polar, therefore water-soluble and can be transported in blood
What is the mode of transport of oxygen in relation to its solubility in water?
Soluble in water and oxygen bound to haemoglobin proteins
What is the mode of transport of fats in relation to its solubility in water?
Insoluble in water and transported in lipoproteins
What is the mode of transport of cholesterol in relation to its solubility in water?
Requires transport in lipoproteins to be transported in the blood, insoluble
