Water Molecules Flashcards
Why is water vital to living organism
1) Water is a metabolite in loads of important metabolic reactions, including condensation and hydrolysis reactions
2) Water is a solvent, which means some substances dissolve in it.Most metabolic reactions take place in solution
3) Water helps with temperature control because it has a high latent heat of vaporisation and a high specific heat capacitor
4) Water molecules are very cohesive (they stick together), which helps water transport in plants as well as transport in other organisms.
How do water molecules have a simple structure
A molecule of water (H20) is one atom of oxygen (O)
joined to two atoms of hydrogen (H2) by shared electrons
How is water polar
-The shared negative hydrogen electrons are
pulled towards the oxygen atom, the other side of each hydrogen atom is left with a slight positive charge.
-The unshared negative electrons on the oxygen atom give it a slight negative charge.
Why do the polar nature of water give it useful properties
-The slightly negatively-charged oxygen atoms attract the slightly positively-charged hydrogen atoms of other water molecules.
-This attraction is called hydrogen bonding and it gives water some of its useful properties.
Why is water an important metabolite
-Many metabolic reactions involve a condensation or hydrolysis reaction.
-A hydrolysis reaction requires a molecule of water to break a bond.
A condensation reaction releases a molecule of water as a new bond is formed.
-For example, amino acids are joined together to make polypeptides (proteins) bycondensation reactions .Energy from ATP is released through a hydrolysis reaction
Why does water having a high latent heat of vaporisation important and how does it have a high latent heat of vapourisation
1) It takes a lot of energy (heat) to break the hydrogen bonds between water molecules.
2) So water has a high latent heat of vaporisation — a lot of energy is used up when water evaporates (vaporises).
3) This is useful for living organisms because it means they can use water loss through evaporation to cool down (e.g. humans sweat to cool down) without losing too much water.
Why can water be a buffer in changes of temperature and why is the important
1) The hydrogen bonds between water molecules can absorb a lot of energy.
2) So water has a high specific heat capacity — it takes a lot of energy to heat it up.
3) This is useful for living organisms because it means that water doesn’t experience rapid temperature changes. This makes water a good habitat because the temperature under water is likely to be more stable than on land. The water inside organisms also remains at a fairly stable temperature — helping them to maintain a constant internal body temperature.
Why is water cohesive and how does that help w
1) Cohesion is the attraction between molecules of the same type (e.g. two water molecules).
Water molecules are very cohesive (they tend to stick together) because they’re polar.
2) Strong cohesion helps water to flow, making it great for transporting substances. For example, it’s how water travels in columns up the xylem (tube-like transport cells) in plants
3) Strong cohesion also means that water has a high surface tension when it comes into contact with air. This is the reason why sweat forms droplets, which evaporate from the skin to cool an organism down. It’s also the reason that pond skaters, and some other insects, can ‘walk’ on the surface of a pond.
