Midterm 1 Flashcards
Nature of Science
Does not equal collecting facts
“To do science is to search for repeated patterns, not simply to accumulate facts (general principles)
Two approaches:
- induction based science (discovery science)
- hypothesis-based science
Induction-Based Science
Inductive/Logical reasoning
Look for patterns -> make predictions about things
Ex. Cell theory - generalities about cells
Ex. Sun rose in the east yesterday and will rise in the east tomorrow
Hypothesis-Based Science
Deductive reasoning
Ex. Jill was at pats game 8:00 Tuesday, jack was at pats game 8:00 Tuesday, therefore jack and Jill were at the same game
Hypothesis (s) - Hypotheses (pl)
-> MUST be testable
Ex. Algae, some species can change. Hypothesis: spiky cell shape = anti-herbivore defence. Use a beaker with added herbivores to either disprove or support your hypotheses. If all stay round reject the hypothesis and make a new one. If the round turn spikey it doesn’t prove the hypothesis but supports it (may be other explanation such as turbulence - keep testing)
Scientific Method
Hypothetical-deductive method (hypothesis - must be testable - and deductive reasoning)
Design an experiment -> get outcome -> predictable if hypothesis is correct
Hypothesis -? Experiments - outcome is predictable -> tabulate results
If not as predicted -> falsified hypothesis -> need a new one
If as predicted -> support for hypothesis -> more experiments
Theories
Theory of relativity:
Hypotheses that attempt to explain a lot
-great explanatory power
For theories to be accepted you need lots of evidence
Occam’s Razor
Principle of logic
If several explanations are compatible with evidence at hand the simplest should be the one considered the most probable
Explanations shouldn’t be more complicated than necessary
Atoms
Basic unit of matter
2+ atoms held together -> molecule
Different types -> elements
Electro negativity (EN)
Property of an atom
Affinity for electrons
Bond between atoms of identical EN=equally shared e-‘s = non-polar covalent with no partial charges (same EN or almost the same EN)
Bond between atoms of slightly differing EN = unequal sharing of e-‘s, partial charges and a polar covalent bond (higher EN gets partial negative charge)
Important: O-H, N-H, O-C, N-C
Bond between very different EN atoms = ionic bond, no e- sharing, higher EN atom takes e- from lower EN atom (ex. Salts)
Non-polar covalent –> polar covalent –> ionic bonds
0 ——— difference in EN ———> big
Strong bonds
Hydrogen bonds
Weak bonds
- transient bond (constantly breaking and re-forming)
- consequence of polar-covalent bonds containing H (H20)
Water
Fundamental to life
Organism are mostly H2O (70-90%)
Biochemistry takes place in aqueous environment
H bonds- lead to water being liquid at room temp as opposed to a gas
Cohesion: Water sticks to itself (ex. Plants pulls water up it)
Adhesion: attracted to solid surfaces that have partial or full charges (ex. Meniscus reading)
Solvent of life (not universal, good for salts(ions) or smallish polar molecules)
Starch
Composed of glucose molecules - linked
Attracts water (polar)
Hydrophilic vs Hydrophobic
“Water liking” vs. “Water fearing”
PH
Measure of acidity
Lower = more acidic
Higher=more basic
7 = neutral
High [H+]=very acidic
Cellular pH is buffered - metabolism is pH dependent (normal cellular pH is 7-7.4)
Carbon Chemistry
C - basis of metabolism - transformations of C-based molecules
Cell structure-molecules in a cell are C bases
Most biological molecules are C based (other stuff attached such as H, O, P and S)
“Lego block” - always has 4 bonds - both non polar or polar covalent bonds
Non-polar: C-C, C-H. Polar: C-O, C-N
Show isomerism
Isomerism
Molecules with same molecular formula but different structures
Structural isomers: variation in linkages around C atoms
Geometric isomers( Cis/Trans isomers) = variation around a double bond (double bonds don’t rotate)
