A1 Unity and Diversity of Molecules Flashcards
Why is water the medium of life?
The first cells originated in water, water remains the medium in which most processes of life occur
What causes the polarity of covalent bonding within water molecules?
Unequal sharing of electrons, causing Oxygen to be slightly negative + Hydrogen slightly positive
What is the cause of hydrogen bonding between water molecules?
The polarity of the water molecules
What is a hydrogen bond (between water molecules)?
Weak temporary bond between H of one water molecue and the oxygen of another
What is cohesion?
Attraction between water molecules, due to hydrogen bonding
How is surface tension created within water?
Hydrogen bonds are formed between all water molecules in all directions. At the surface, the hydrogen bonds are stronger (and fewer). Therefore, the top layer is the strongest layer of bonds and is hardest to break.
What does surface tension mean for organisms?
Light objects/animals are able to move across without breaking the hydrogen bonds
What is the effect of cohesion within plants?
When one H2o evaporates out of the stomata, another one is pulled up. Therefore, the hydrogen bonds between the water allows for the continuous flow of movement up a thin tube (xylem)
What is the impact of water being adhesive to materials that are polar/charged?
Water is adhesive to sides of xylem vessel, allowing water not to fall back down the vessel. In this way, adhesion helps water ‘stick’ to plant cell walls
What does hydrophilic mean?
Substance that readily dissolves in water / polar molecules that don’t dissolve but are attracted
What does hydrophobic mean?
Not attracted to water. Does not dissolve in wter
What is buoyancy?
Upward force exerted on an object when it is placed on a medium
What is visocity?
Stickiness of a fluid, which determines its ability to flow
What is thermal conductivity?
The rate at which heat passes through a material
What is specific heat capacity?
How much heat can be absorbed without changing temperature
What are some hydrophilic molecules, important for living organisms?
Salt, glucose, cellulose
What are some hydrophobic molecules, important for living organisms?
Fats, hormones
Where do most enzyme catalyst reactions occur?
In water
Are all molecules hydrophilic?
No, function of some molecules in cells depend on them being hydrophobic and insoluble
How are polarity and water’s solvent properties related?
Water’s polarity enables it to dissolve and surround charged ions with water molecules
What are water’s buoyancy levels?
Reasonably high. If an object has a low density, it could flow
What are air’s buoyacy levels?
Almost no buoyancy force
What is the visocosity of water?
Reasonable viscosity for a liquid, due to hydrogen bondsW
What is the viscosity of air?
Almost none, objects move with little resistance