Biology Notes (Exam Guide 2)

Evolution

• the unity and diversity of organisms

• living organisms are modified descendants of common ancestors

Emergence

The whole is more than just the sum of its parts

emergent properties

new process etc that only appear when two thing are put together in a certain way

science

a method of inquiry: seeking natural explanations of natural phenomena 

• limited to what is observable and measurable

• systematic investigation of the natural world

hypothesis

testable explanation for observations based on available data

prediction (follows hypothesis)

what you expect to see when you tests your hypothesis

theory

broad explanation with significant support (meaning there is proof or that it was tested multiple times and people)

law

statement of what always occurs under certain circumstances

scientific method

1. observation

2. background research

3. hypothesis

4. prediction

5. experiments

6. evaluate

4 elements that make up 96% of living matter (CHON)

1. carbon

2. hydrogen

3. oxygen

4. nitrogen

atoms 

protons, neutrons, and electrons

• atoms make up elements

element

basic structure of matter

electrons

• have a -1 charge

• move rapidly

• determine how atoms interact

• the further away e- is from the nucleus, the more potential energy e- possesses

• when e- becomes excited, it can be used to do work

electron shell

an electron’s potential energy

valence shell

outermost shell where bonds between electrons form

electronegativity

tendency of an atom to attract an electron (affinity for e-)

• as electronegativity increases, tendency to hog electrons increases too

• higher electronegativity = more reactive

• electronegativity increases from left to right on the periodic table

covalent bond

equal sharing of electrons 

• intramolecular bond within a molecule (sharing a pair of valence electrons by two atoms) 

• strong bond

• two types:

- non polar, same electronegative share e- equally

- polar, greater than 2 diff electronegative share e- equally, causes molecules to have sides 

ionic bond

between charged atoms, one atom steals e- from the other (transfer)

• intramolecular bond

• less than 2 diff electronegativity

• bond is formed by attraction between anion (+) and cation (-)

van der Waals

forces develop because e- are in constant motion can result in attractions between molecules

• dipole dipole

• London dispertion force

• lizards sticking to the wall

intermolecular

interactions between molecules

hydrogen bond

stick polar covalent molecules together

• really strong dipole-dipole interaction

• stickiness between water molecules, an attraction

- Polarity allows water molecules to form attractions to each other

- since water is polar, 1 molecule of water forms hydrogen bonds with other water molecules

• lead to 4 emergent bond

cohesion

water molecules stick to each other

adhesion

water molecules stick to other polar things

moderate temperature

water’s high specific heat makes it hard to change water temperature

• high heat of vaporization makes it hard to change state

water

• expands upon freezing 

• ice floats 

• hydrogen bonds in ice make air pockets 

• water reaches its greatest density at 4 C

universal solvent, substances can either be:

hydrophilic (love water) or hydrophobic (afraid of water)