BIO 152 BIOLOGY FINAL EXAM STUDY NOTES FOR REVISION LATEST UPDATE

Lecture 2: : Water, Carbon, & Macromolecules Part A (Ch 2-5)
● Etymology
- hydro: water
- lysis: break
- phobic: scared of
- philic: like
● subatomic particle
- protons and neutrons form atomic nucleus
- electron form a cloud of electron surrounding the nucleus
- valance shell determine the atom’s behaviour
● covalent bond
- sharing a valence electron by two atoms
- eletronegativity: atoms attraction for electrons in a covalent shell
- HIGHER electronegativity is stronger atomic attraction toward itself
O>N>C~H
- pure covalent bond, two same atoms shared electrons
- non polar covalent bond, share electrons equally
- polar covalent bond, one is higher electronegativity, the electron shared
unevenly.
- When the number of electronegativity is lower that mean it is more positive
- the arrow is point to the negative side
● Hydrogen bond
- form when H atom in one molecule bound attract to another molecule
- usually bond with O or N
- water is polar molecule because of the highly electronegativity of oxygen
- charge in unevenly distribute
- Polarity allows water molecules to form hydrogen bonds with each other
● water
- cohesive behaviour(有黏著力的) due to the properties of polarity of water
- Ability to moderate temperature(Absorbs heat from warmer air and releases
stored heat to cooler air)
- Ability to moderate temperature the bond formed a even pattern when it reach
freeze point (make ice less dense)
- versatility(多用途) as solvent
- h bond hold water molecules together
- cohesion: hold the water colume
- adhesion: helps transport water against gravity
- hotter temperature break water molecules
● Acidification: A Threat to Water Quality
- CO2 main product of fossil fuel combustion
- • ~25% of human-generated CO2 is absorbed by the oceans
- • CO2 dissolved in sea water forms carbonic acid → Ocean acidification