Water for life Flashcards
Why is water important?
most animals are 75-95% water
many live in water
most chemical reaction of life happen in water
What are qualities of the water molecule?
Has two hydrogens and one oxygen
polar covalent bond(negative and positive charged ends)
What end of the H2O molecule is negative?
Oxygen
What are benefits of hydrogen bonds?
cause attraction between other water molecules, therefore, cohesion, adhesion, capillary action and surface tension
helps with thermal properties
What are properties of hydrogen bonds?
weak bond if there are only a few
very strong if there are many
most stable in lattice form/solid (ICE)
How do water molecules arrange themselves?
In tetrahedral formation
What is cohesion?
the ability to stick to itself
What is adhesion?
the ability to stick to other surfaces that are non-water polar or charged
How can cohesion and adhesion work together?
capillary action and surface tension
What is capillary action?
is when water sticks to itself in the xylem of a plant and using adhesion sticks to the side of the plant and climbs upward from roots to leaves
What is surface tension?
when surface of water is strong enough to support insects/ lets droplets form (e.g. on leaves)
What can you tell me about ice density?
Unusual as it is less dense than water
water freezes from top to bottom, therefore, organisms in lake will NOT FREEZE
hydrogen bonds are stable (not constantly breaking)
How do you know that ice is less dense than liquid water?
BECAUSE IT FLOATS!!
What are some properties of water?
High specific heat capacity
high vaporisation
good coolant
solvent
transport medium
metabolic react
diffusion
transparent
What does ‘high specific heat capacity’ mean?
takes a lot of energy for temperature of water to change
due to numerous H bonds
Why is it important that water is a good coolant?
high temps. = denatured proteins = death
because of high specific heat capacity water takes longer to heat and cool so when water evaporates it removes a lot of heat energy
What is the benefit of water being transparent?
It can reach organisms on the sea floor
What does ‘high vaporisation’ mean?
takes a lot of energy to evaporate
How is water a good solvent?
Can dissolve many organic & inorganic substances
Can cause dissociation of ionic compounds bc. of H20 polar attraction
Tell me about metabolic reaction?
happen most readily in solutions of water - water in cells dissolves reactants & substrates
How does metabolic reaction affect diffusion?
since cells are mainly water, therefore, diffusion is easier if substance concerned is in solution
e.g. oxygen from alveoli to blood
How is water a good transport medium?
because of metabolic reaction and diffusion, once the needed substance is diffused in cell that cell can then travel the body or plant to reach it’s destination and diffuse there
E.g. sucrose in plants, nutrients, waste products, circulatory system
What is the definition of hydrophobic?
afraid of water
a substance that does not combine with water
always non-polar substance
e.g. oil
What is the definition of hydrophilic?
water loving
a substance that is chemically attracted to water
always polar molecules/ positive & negative ions
e.g. glucose, cellulose
How does water compare to CH4 (methane) ?
molecular mass - 16 v. 18 polarity - non v. polar density (g cm-3) - 0.46 v. 1 specific heat capacity (J g-1) 2.2 v. 4.2 heat of vaporisation - 760 v. 2257 melting point - 182 v. 0 boiling point - -160 v. 100
