Biology chapters 2-4

Levels of biological organization

Levels of biological organization

1. Biosphere, 2. Ecosystems, 3. Communities, 4. Populations, 5. Organisms, 6. Organs, 7. Tissues, 8. Cells, 9. Organelles, 10. Molecules, 11. Atoms

Matter

anything that takes up space and has mass

Elements

a substance that cannot be broken down into other substances by chemical reactions (92 naturally occurring elements)

Compound

a substance made up of two or elements combined in fixed proportions

A compound has characteristics

different of the elements that compose it

Essential elements

elements an organism needs to survive; 20-25% of the 92 natural elements are essential (humans need 25, plants need 17)

Oxygen, Hydrogen, Carbon, and Nitrogen make up

~96% of living matter; other 4%: Calcium, Phosphorus, Potassium, Sulfur, trace elements

Trace elements

required by an organism in minute amounts

Atom

smallest unit of matter that still retains the properties of an element

Subatomic particles

neutrons, protons, electrons

Atomic nucleus

dense core at the center of an atom where protons and neutrons are packed

Dalton

unit of measurement for subatomic particles; same as the atomic mass unit (amu); neutrons + protons have masses close to 1 dalton

Atomic number

number of protons in an atom

Mass number

total number of protons and neutrons in an atom

Atomic mass

total mass of an atom

Isotopes

different atomic forms of the same atom (different number of neutrons)

Radioactive isotopes

an isotope in which the nucleus decays spontaneously giving off particles and energy; used as diagnostic tools in medicine and in advanced imaging instruments

Half-life

the time it takes for 50% of the parent isotope to decay

Radioactive dating

a process where scientists measure the ratio of different isotopes and calculate how many half-lives have passed since an organism was fossilized or a rock was formed

Energy

the capacity to cause change

Potential energy

the energy that matter possesses because of its location or structure

Electrons have potential energy because of their

distance from the nucleus

Electron shells

where electrons are found (each with a characteristic distance and energy level)

Valence electrons

determine the chemical behavior of an atom

Valence shell

outermost electron shell

Orbital

3D space where an electron is found 90% of the time; each orbital has a max of two electrons; s,p, etc.

Chemical bonds

attractions between two atoms resulting from the sharing of outer-shell electrons or the presence of opposite charges on the atoms

Bonds ranked in order of strength

1. Covalent, 2. Ionic, 3. H-bonds, 4. Van Der Waals

Covalent bond

sharing of a pair of valence electrons by two atoms

Molecule

two or more atoms held together by covalent bonds

Valence

the bonding capacity of an atoms; usually the number of unpaired electrons

Electronegativity

the attraction of a particular atom for the elections of a covalent bond

Nonpolar covalent bond

electrons are shared equally

Polar covalent bond

electrons are shared unequally

Ion

an atom or molecule that has gained or lost one or more electrons, gaining a charge

Cation

positive charge

Anion

negative charge

Ionic bond

a chemical bond resulting from the attraction of oppositely charged ions

Ionic compound

a compound resulting from the formation of an ionic bond (salt)

Ionic compound are not

molecules

Not all salts have the same number of

anions and cations

Hydrogen bond

the attraction between a hydrogen and an electronegative atom

Van Der Waals interactions

weak interactions between molecules/ parts of molecules that result from transient partial charges

Chemical reactions

the making and breaking of chemical bonds, leading to changes in the composition of matter

Reactant

starting material in a chemical reaction

Product

material resulting from a chemical reaction

Chemical equilibrium

in a chemical reaction, the state in which the rate of the forward reaction equals the rate of the reverse reaction, so that the relative concentrations of the reactants and products do not change with time; dynamic equilibrium

Polar molecule

a molecule with an uneven distribution of charges in different regions of the molecule

Cohesion

the linking together of like molecules, often with H-bonds; helps contribute to the transport of water and dissolved nutrients against gravity in plants

Adhesion

the clinging of one substance to another; helps counter to downward pull of gravity

Surface tension

a measure of how difficult it is to stretch or break the surface of a liquid; water has a high surface tension because of the H-bonding of surface molecules

Kinetic energy

the energy of motion

Thermal energy

kinetic energy due to the random motion of atoms and molecules

Temperature

a measure of the average kinetic energy of the atoms and molecules in a body of matter

Heat

thermal energy in transfer from one body of matter to another

Calorie

the amount of heat energy needed to raise the temperature of 1g of water by 1ºC

Kilocalorie

1000 calories

Joule

one unit of energy

Specific heat

the amount of heat that must be absorbed or lost for 1g of a substance to change temperature by 1ºC

Heat of vaporization

the amount of heat a liquid must absorb for 1g of it to be converted from a liquid to a gaseous state

Evaporative cooling

the process in which the surface of an object becomes cooler during evaporation, a result of the molecules with the greatest kinetic energy changing from the liquid to the gaseous state

Solution

a liquid that is a completely homogeneous mixture of 2+ substances

Solvent

dissolving substance

Solute

dissolved substance

Aqueous solution

the solute is dissolved in water, the solvent

Hydration shell

the sphere of water molecules around each dissolved ion

Hydrophobic

substance that appears to repel water

Hydrophilic

substance that appears to have an affinity for water

Molecular mass

the sum of the masses of all the atoms in a molecule

Mole (mol)

the number of grams of a substance that equals its molecular/ atomic mass in daltons

Avogadro's number

6.02 x 10^23

Molarity

the number of moles of solute per liter of solution

Hydrogen ion

a singular proton with a +1 charge

Hydroxide ion

water molecule that just lost a proton (OH-)

Hydronium ion

a water molecule that has an extra proton bound to it (H3O+)

Acid

substance that increases the H+ ion concentration of a solution

Base

substance that reduces the H+ ion concentration of a solution

Acid base formula

([H+][OH-]=10^-14)

pH formula

pH = -log[H+]

Buffer

a substance that minimizes changes in the concentrations of H+ and OH- in a solution by accepting H+ from the solution when they are in excess and donating H+ when they are depleted

Ocean acidification

CO2 dissolving in seawater and reacting with water to form carbonic acid, lowering the ocean’s pH; CO2 + H2O → H2CO3, H2CO3 → H+ + HCO3-, H+ + CO3(2-) → HCO3-, CO3(2-) + Ca(2+) → CaCO3

Organic chemistry

the study of carbon compounds

Miller’s experiment

proved complex organic molecules could arise spontaneously under conditions thought at the time to have existed on early Earth; used CH4, CO2, H2S, and NH3

Carbon electron shells/shape

2 in first cell, 4 in second shell; carbon forms tetrahedrons (< between bonds is 109.5º)

Carbon branches can be

straight, branched, arranged in closed rings

Hydrocarbons

an organic molecule consisting only of carbon and hydrogen

Isomers

compounds that have the same number of atoms of the same elements but different structures and hence different properties

Structural isomers

one of two or more compounds that have the same molecular formula but differ in the covalent arrangements of their atoms

Cis-trans isomers

one of several compounds that have the same molecular formula and covalent bonds between atoms but differ in the spatial arrangement of their atoms owning to the inflexibility of double bonds

Enantiomers

isomers that are mirror images of each other and that differ in shape due to the presence of an asymmetric carbon, one that is attached to four different atoms or groups of atoms

Cells are about _____% water

70-95%

Ionic compounds are not

molecules

Every water molecule can make ____ H-bonds

4

When the temperature rises H-bonds

break

When the temperature lowers H-bonds

form

Heat is _____ when H-bonds break

absorbed

Heat is _____ when H-bonds form

released

In liquid water has a maximum of ___ H-bonds

3

Acid rain has which acids?

nitric acid and sulfuric acid

pH 1

battery acid