Unit 1 test Bio

biology

the study of life

science

an approach to understanding the natural world, systematic knowledge gained through observation and experimentation, a branch of study dealing with facts or truth showing the operation of general laws

inductive reasoning

from specific to general

deductive reasoning

from general to specific

hypothesis

must be testable and falsifiable

control variables

seeks to answer a question, repeatable, flexible

independent variable

what is manipulated, x-axis

deoendent variable

what is measured, y-axis

controlled variable

kept constant or limited so they don't affect the outcome

element

substance that cannot be broken down further by chemical reactions

key elements

carbon, hydrogen, oxygen, nitrogen

what determines properties of an element

the element's electrons, structure of atoms

compounds

a substance with 2 or more elements combined in a fixed ratio

atom

smallest unit that retains the properties and therefore identity of the element

valence

outermost shell, may participate in chemical reactions

expected result of a full valence shell

it will not participate in reactions (inert) because it has no desire to donate or gain electrons

H full valence

1

O full valence

2

N full valence

3

C full valence

4

isotopes

same identity (protons) but different mass (neutrons)

stable isotopes

dont decay

unstable isotopes

can decay, gives off energy

chemical bonds

attractions between atoms based on shared or transferred valence electrons

how do chemical bonds form

by the attraction between the positive nucleus of one atom and the negative electrons of another atom

covalent bonds

a pair of valence electrons are shared between 2 atoms

ionic bonds

electrons are donated because 1 atom is more electronegative

covalent bonds can be...

single or double, polar or non polar, hold atoms together

ionic bonds...

transfer negative charge, cations & anions, ions created when electrons are transferred

polar bonds

one atom is more electronegative than the other so electrons are pulled to one atom and there are partial charges on each atom

nonpolar bonds

a covalent bond in which electrons are shared equally, no partial charges

electronegative

the more electronegative an atom is the more strongly it pulls the shared electron towards itself

hydrogen bonds are...

weak

hydrogen bonds

is a bond between water molecules and a non covalent attraction between a covalently bonded H and a dif electronegative atom

in a hydrogen bond

H has a partial + charge

strong bond

hard to break, often covalent

weak bond

easy to break, hold large molecules in their functional form, reversible

what determines shape of a molecule

bonds determined by valence electron arrangment and positions of atoms orbitals.

what determines molecular function

molecular shape

matter gets _______ as chemical reactions occur

rearranged (matter cant be created or destroyed)

what is chemical equilibrium

the point where forward and reverse reactions occur at the same rate therefore concentrations stop

- doesnt mean concentrations are equal

- dynamic equilibrium

chemical structure of water

- 2H(+) , 1O(-)

- shaped like a V

- two H bonded to O with single covalent bonds

- oxygen is more electronegative than hydrogen so the oxygen will hog the electrons. This makes water polar

what kinds of bonds does water have internally

internal polar covalent bond because oxygen is more electronegative than hydrogen so electrons spend more time closer to it

what kinds of bonds form between water molecules

hydrogen bonds

what emergent properties result due to the polarity of water

- cohesion of water molecules

- moderation of temp by water

- water is the solvent of life

- floating of ice on liquid water

cohesion of water molecules

- hydrogen bonds hold water molecules together

- cohesion and adhesion allow plants to transport water

- cohesion results in high surface tension ( H bonds resist being stretched)

moderation of temp by water

- water absorbs heat when air is warm and releases heat when air is cool

- happens because of KE and atoms always moving

- temp is average KE

specific heat

The amount of energy required to raise the temperature of 1 gram of a substance by 1 degree celcius

heat of vaporization

The amount of energy required for the liquid at its boiling point to become a gas

why is there high specific heat and high vaporization

because hydrogen bonds heat is needed to break bonds and when broken, bonds release heat

how does high sp and hov impact cells, organisms, and the planet?

- bodies of water moderate temp

- organisms and cells resist temp change

- evaporative cooling allows temp stability for organisms, regions, and the planet

why does ice float on water?

- water expands as it freezes because hydrogen bonding

- ice is less dense than water

in liquid water hydrogen bonds

break and reform

in ice hydrogen bonds are

stable

what kinds of molecules can water dissolve?

- ionic compounds (salt)

- non-ionic polar compounds (sugar)

- large molecules with polar and ionic regions

adhesion

the clinging of one substance to another, such as water to plant cell walls, in this case by means of H bonds

cohesion

the linking together of like molecules, often by H bonds

solvent

The dissolving agent of a solution. Water is the most versatile solvent

solute

a substance that is dissolved in a solution

hydrophillic

water loving, attracting, doesnt always mean it will dissolve

hydrophobic

water fearing, non polar hydrogen - carbon bonds

cell membranes are

hydrophobic

3 characteristics of the dissociation of water

1. it is reversible (both reactions are happening are at dynamic equilibrium)

2. it is rare

3. important

acids

substance that increases hydrogen ion concentration of a solution, donates H+

bases

substance that reduces the hydrogen ion concentration, accepts H+, forms OH

strong acids/bases

disassociate completely, HCl, NaOH

weak acids/bases

partially disassociate, NH3, carbonic acid

buffers

weak + conj

buffers are...

a substance that minimizes the changes in concentrations of hydrogen ions and hydroxide ions in a solution

how does carbon bond

- 4 valence electrons, each carbon is a decision point where a molecule can branch in up to 4 directions

- leads to structural diversity

- double or single bonds

how does molecular diversity result because of carbon bonding

- dif lengths

- dif location of double bonds

- branching

- formation of rings

ex of isomers

L-dopa reduces symptoms of parkinsons, R-dopa does nothing

structural isomers

same formula dif arrangement, number of possible isomers increase as size increases

cis-trans isomers

- arrangement of functional groups in relation to double bonds or rings

- leads to dif shapes (function, properties)

enantiomers isomers

- mirror images

- dif shapes, properties, function

hydroxyl

OH, alcohols, ex. ethanol

hydroxyl properties

- polar because electrons spend more time with electronegative oxygen

- can form hydrogen bonds with water, helping dissolve organic compounds such as sugars

carbonyl

C=O, ketones( (within carbon skeleton) and aldehydes (end of skeleton)

carbonyl properties

- ketone and aldehydes are structural isomers with different properties, ex. propanal and acetone

- ketone and aldehyde groups found in sugars, ex. ketoses and aldoses

carboxyl

COOH, carboxylic acids or organic acids

carboxyl properties

- acts as acid because it can donate H+ because of the bind between O and H is so polar

- found in cells in the ionized atom with 1- charge called a carboxylate ion

amino

NH2, amines

amino properties

- acts as base because it can pick up H+ from the surrounding solution

- found in cells in the ionizd from with 1+ charge

sulfhydryl

SH, thiols

sulfhydryl properties

- 2 sulfhydryl groups can react, forming a covalent bond

- helps stabilize protein structure

- hair straight or curly

phosphate

OPO3, organic phosphates

phosphate properties

- contributes negative charge (2- when at the end of a chain, 1- when internally in a chain)

- molecules containing phosphate groups have potential to react with water releasing energy

methyl

CH3, methylated compounds

methyl properties

- The addition of methyl group to DNA or molecules bound to DNA affects the expression of genes

- Arrangement of methyl groups in male and female sex hormones affects their shape and function

ATP

adenosine tri phosphate

what does ATP do?

- Transports chemical energy within cells

- can react with water molecules or other molecules forming ADP and inorganic phosphate

- releases energy

macromolecules

large molecules made from polymers built from monomers

polymer

molecules consisting of similar or identical building blocks which are linked by covalent bonds

monomer

the building blocks

how are macromolecules formed

- monomers are connected by dehydration reactions

- one provides OH one provides H

how are macromolecules dissembled

- hydrolysis

- reverse of dehydration reaction

enzymes

- macromolecule that is usually a protien (end in ase)

- works as catalyst

carbs

- sugars and sugar polymers

- made of C, H. and O

- carbonyl group

role of carbs

serve as fuel and building material for cells