Biological Molecules; Physical Properties of Water
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?- Created by: Phoebe Lambdon
- Created on: 05-03-13 18:55
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- Physical Properties of Water
- Polar molecule forming hydrogen bonds. Non-linear molecule. H-bonds are weak but together make water very stable. Oxygen more negative due to more electrons; hence unequal negative charge. H-bonds formed due to electrostatic attraction
- Hydrogen bonds in a water molecule.
- Weak hydrogen bonds allow water to exist as a liquid
- Hydrogen bonds in a water molecule.
- A good solvent
- An excellent solvent for other polar molecules and ions. e.g Nitrates/Mg2+/ O2/CO2
- Allows metabolic reactions to take place. Allows ions to be mobile. Used as a transport system e.g blood, lymph, xylem, phloem.
- An excellent solvent for other polar molecules and ions. e.g Nitrates/Mg2+/ O2/CO2
- High specific heat capacity.
- A large amount of energy is required to raise the temperature of water by 1oC; slow to warm up and slow to cool down
- Allows for minimum fluctuations of temperature within cells and large bodies of water called thermal stability buffer. [enzymes = temperature sensitive]
- A large amount of energy is required to raise the temperature of water by 1oC; slow to warm up and slow to cool down
- High latent heart of vapourisation
- H-Bonds attract water molecules so difficult to escape as vapour. Hence high boiling point.
- Allows organisms to evaporate water in the cooling process e.g sweating (thermoregulation)
- H-Bonds attract water molecules so difficult to escape as vapour. Hence high boiling point.
- High latent heat of fusion
- Energy required in changing a liquid into a solid.
- Reduces chances of ice crystals forming in cells.
- Energy required in changing a liquid into a solid.
- Water molecules are attached to each other; know as COHESION
- Due to H-bonding.
- Surface tension exists on the surface of water e.g pondskaters and transpiration stream.
- Due to H-bonding.
- Water molecules attached to other surfaces; known as ADHESION
- Due to H-bonding
- A driving force for the upward movement of water in xylem vessels.
- Due to H-bonding
- Capillarity properties- particularly in very narrow vessels.
- Due to adhesive forces causing high tensile strength. Very difficult to break column of water.
- Allows upward movement of unbroken columns of water in very fine vessels e.g xylem vessels.
- Due to adhesive forces causing high tensile strength. Very difficult to break column of water.
- The density of water decreases as the temperature falls below 4oC . Water expands as it freezes; maximum density is at 4oC
- Ice therefore floats on the top of a pond. Water molecules in ice fit better together than in water; but spread out into a crystal structure
- Ice can insulate the pond below. Water below doesn't freeze. Allows nutrient to circulate.
- Ice therefore floats on the top of a pond. Water molecules in ice fit better together than in water; but spread out into a crystal structure
- Cannot be easily compressed.
- Due to cohesive forces
- Used as a support structure in hydrostatic skeletons e.g jellyfish and earthworms. Bouyancy
- Due to cohesive forces
- Acts as a lubricant.
- Due to cohesive and adhesive forces.
- Synovial fluid. Mucus. Pericardial fluid. Amniotic fluid.
- Due to cohesive and adhesive forces.
- Transparency
- Allows for photosynthesis in aquatic plants and visibility of aquatic organisms.
- Different wavelengths penetrate the sea at different depths.
- Allows for photosynthesis in aquatic plants and visibility of aquatic organisms.
- Takes part /chemical reagent in chemical reactions
- Photosynthesis
- 6H2O + 6CO2 ---> C6H12O6 + 6O2
- Photosynthesis
- Involved in the breaking of chemical bonds.
- Hydrolysis; addition of water.
- Catabolic reactions
- Hydrolysis; addition of water.
- Involved in the formation of bonds.
- Condensation; removal of water
- Anabolic reactions
- Condensation; removal of water
- Low viscosity
- Due to freedom of movement of water molecules. H-bonds break and reform
- Allows free movement of organisms (to swim)
- Due to freedom of movement of water molecules. H-bonds break and reform
- Structure and support in plant cells.
- Makes plant cells turgid.
- Polar molecule forming hydrogen bonds. Non-linear molecule. H-bonds are weak but together make water very stable. Oxygen more negative due to more electrons; hence unequal negative charge. H-bonds formed due to electrostatic attraction
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