Water
Functions
- As a reactant (X presence)
- Photosynthesis: food produced from water and CO2
- Hydrolysis: breaking down substance with the use of one water molecule
- As a solvent for dissolving chemicals
- Osmosis/Diffusion: all materials (eg. gas) which enter/leave living cells only in
aqueous medium
- Main component of cytoplasm of cells: chemical reactions take place in aqueous
medium
- As a medium of transport
- A component of blood plasma: transport substances ard body
- Plants: inorganic ions dissolve in water and are carried from roots to other parts
- As a cooling agent
- Animals: sweating (water remove heat when evaporates)
drink more water in hot weather to compensate water loss
Otherwise body temp rise rapidly
> Heat stroke (can’t sweat, reddening of skin surface, dizziness)
- Plants: transpiration
- As supporting agent
- Plants: cells full of water are turgid
> pressure: press against each other
> support to stand upright
- Jellyfish: hydroskeleton to maintain shape
- Aquatic organisms: buoyancy
- Maintaining stable temperature
- Water of ocean/lakes absorb heart w/o much temp change
high specific heat capacity
> suitable habitat for aquatic organisms
- As a component of lubricant
- ↓ friction during movement
- Pleural fluid ard human lungs: ↓ friction when breathing
Water as a solvent
- Cohesive: transport; adhesive: solvent
, Chemical properties
Water molecules form dipole (charged molecule)
● H end: slightly positive
● O end: slightly negative
>> create weak hydrogen bonds w nearby
molecules
>> cohesive (stick tgt), require more energy to
separate into (g)
1. Water molecules link together to form a 2. Water molecules stick to other charged
continuous stream of water (cohesive) molecules (adhesive)
Plants: from root to leaf, up xylem tubes Surround them, take them into (aq)
(adhesive) - Universal solvent: enzymes (eg.
- Loss of 1 molecule by evaporation > pull lysozyme) and hormones
on the ones behind
- Transpiration pull: water transport
Blood: via blood vessels (adhesive)
3. High thermal capacity 4. Surface tension
Create consistent temp for aquatic life eg. pond skater living on water
Big cooling effect: evaporation requires
significant amount of energy
Different circulatory systems
Prokaryotic organisms: X circulatory system
- Large SA:volume ratio > short diffusion pathway
Multicellular organisms: need mass transport system
- Too big, small SA:volume ratio > long diffusion pathway, slow diffusion rate
- Transport by mass flow: one-directional movement of particles in liquid due to pressure
difference
Open circulatory system Closed circulatory system
<maintain higher pressure>
Eg. cricket Single circulation Double circulation
Open ended blood vessels Eg. fish, earthworm Eg. amphibian, reptiles, birds and
Haemolymph circulation around mammals
haemocoel (body cavity), drawn 1 atrium
into heart when heart relaxes 1 ventricle 2 atria
, Haemocyanin: carry oxygen (2 Low blood pressure after 2 ventricles
Cu atoms to bind O2) leaving gills Blood flows through heart twice
per complete circuit of body:
- Pulmonary circulation
- Extra contraction
- Systemic circulation
Higher blood pressure
Higher O2 transport efficiency
Allow higher metabolic rate
Amphibian: no septum
Reptiles: hole in septum, extra
Small animals artery
- Low metabolic rate - Lower O2 concentration
- Short diffusion distance gradient
Advantage: Low energy - Lower O2 diffusion rate
requirement into body cells
Birds, mammals: complete
septum
Human circulatory system
Myogenic heart: never fatigues, lactic acid X build up
Functions
- As a reactant (X presence)
- Photosynthesis: food produced from water and CO2
- Hydrolysis: breaking down substance with the use of one water molecule
- As a solvent for dissolving chemicals
- Osmosis/Diffusion: all materials (eg. gas) which enter/leave living cells only in
aqueous medium
- Main component of cytoplasm of cells: chemical reactions take place in aqueous
medium
- As a medium of transport
- A component of blood plasma: transport substances ard body
- Plants: inorganic ions dissolve in water and are carried from roots to other parts
- As a cooling agent
- Animals: sweating (water remove heat when evaporates)
drink more water in hot weather to compensate water loss
Otherwise body temp rise rapidly
> Heat stroke (can’t sweat, reddening of skin surface, dizziness)
- Plants: transpiration
- As supporting agent
- Plants: cells full of water are turgid
> pressure: press against each other
> support to stand upright
- Jellyfish: hydroskeleton to maintain shape
- Aquatic organisms: buoyancy
- Maintaining stable temperature
- Water of ocean/lakes absorb heart w/o much temp change
high specific heat capacity
> suitable habitat for aquatic organisms
- As a component of lubricant
- ↓ friction during movement
- Pleural fluid ard human lungs: ↓ friction when breathing
Water as a solvent
- Cohesive: transport; adhesive: solvent
, Chemical properties
Water molecules form dipole (charged molecule)
● H end: slightly positive
● O end: slightly negative
>> create weak hydrogen bonds w nearby
molecules
>> cohesive (stick tgt), require more energy to
separate into (g)
1. Water molecules link together to form a 2. Water molecules stick to other charged
continuous stream of water (cohesive) molecules (adhesive)
Plants: from root to leaf, up xylem tubes Surround them, take them into (aq)
(adhesive) - Universal solvent: enzymes (eg.
- Loss of 1 molecule by evaporation > pull lysozyme) and hormones
on the ones behind
- Transpiration pull: water transport
Blood: via blood vessels (adhesive)
3. High thermal capacity 4. Surface tension
Create consistent temp for aquatic life eg. pond skater living on water
Big cooling effect: evaporation requires
significant amount of energy
Different circulatory systems
Prokaryotic organisms: X circulatory system
- Large SA:volume ratio > short diffusion pathway
Multicellular organisms: need mass transport system
- Too big, small SA:volume ratio > long diffusion pathway, slow diffusion rate
- Transport by mass flow: one-directional movement of particles in liquid due to pressure
difference
Open circulatory system Closed circulatory system
<maintain higher pressure>
Eg. cricket Single circulation Double circulation
Open ended blood vessels Eg. fish, earthworm Eg. amphibian, reptiles, birds and
Haemolymph circulation around mammals
haemocoel (body cavity), drawn 1 atrium
into heart when heart relaxes 1 ventricle 2 atria
, Haemocyanin: carry oxygen (2 Low blood pressure after 2 ventricles
Cu atoms to bind O2) leaving gills Blood flows through heart twice
per complete circuit of body:
- Pulmonary circulation
- Extra contraction
- Systemic circulation
Higher blood pressure
Higher O2 transport efficiency
Allow higher metabolic rate
Amphibian: no septum
Reptiles: hole in septum, extra
Small animals artery
- Low metabolic rate - Lower O2 concentration
- Short diffusion distance gradient
Advantage: Low energy - Lower O2 diffusion rate
requirement into body cells
Birds, mammals: complete
septum
Human circulatory system
Myogenic heart: never fatigues, lactic acid X build up
