Biology 111 Test 1

Inductive reasoning

scientists derive generalizations based on a large number of specific observations

hypothesis-based science

tentative answer to a well-framed question; prediction that can be tested

A scientific hypothesis must have two qualities:

must be testable and must be falsifiable (able to be proved false)

Who was the first to define the scientific method?

Sir Francis Bacon

Basic functions of life (all living things have to meet these criteria)

Order

Sensitivity to stimulus

Reproduction

Adaptation

Growth and development

Regulation/homeostasis

energy processing

evolution

A scientific theory is:

Broad in scope

Levels of Bio organization (in order smaller to bigger)

Atoms, molecules, macromolecules, organelles, cells, tissues, organs, organ system, organism, population, community, ecosystem, biosphere

Cells

are the lowest organization of life, enclosed by a membrane, use DNA as genetic info

What is the basis of all multicellular organisms

Cell division

Eukaryotic cells

contains a membrane-bound nucleus and membrane-bound organelles

prokaryotic cells

single-celled; no nucleus or organelles

taxonomy

branch of biology that classifies species into hierarchal order

What are the 3 present day higher levels of classification?

Domains: bacteria, archaea and eukarya

What kingdoms does the eukarya include?

protista, plantae, fungi and anamalia

Phylogenetic tree

constructed by Carl woese, shows the branches of the 3 domains

All life shares

DNA, mRNA, tRNA, ribosomes, proteins made up of 20 amino acids

What did Charles Darwin write?

On the Origin of species by natural selection (1859)

Main points of On the Origin of species by natural selection

Descent with modification (genetics) and Natural selection (ecology)

Natural selection

evolutionary process that occurs when a populations genetics favor the reproductive success of some individuals over others

Most important elements in the living world

carbon, oxygen, hydrogen, nitrogen

2 main regions of the atom

nucleus, orbital cloud

What do elements consist of

a different kind of atom different from other elements

relevant subatomic particles

neutrons, protons and electrons

Neutron charge

neutral

Proton charge

positive

electron charge

negative

the atomic number of an element is

the number of protons and is unique to each element

the atomic mass is

the sum of protons plus neutrons in the nucleus of an atom

Isotopes

different forms of an element that have the same number of protons but a different number of neurons

What type of isotope is unstable

radioisotopes

molecules

2 or more atoms chemically bonded together

Bohr model

electrons exist within the lowest energy shell available

valence electrons

lie in the outermost valence shell and determine the chemical behavior of an atom

octet rule

atoms want to get 8 electrons in their valence shell for stability

what is the characteristic valence of hydrogen

1

what is the characteristic valence of oxygen

2

what is the characteristic valence of nitrogen

3

what is the characteristic valence of carbon

4

electron orbitals

3d space where an electron is found most of the time, can be filled with 2 electrons

What does the line in a structural formula of a molecule mean?

Shared electron

Difference between a molecule and a compound

a molecule is two or more atoms held together by chemical bonds and a compound is two or more atoms that are chemically united

Law of conservation of matter

Principle stating that matter cannot be created or destroyed, only transformed or rearranged in a chemical reaction

Are chemical reactions reversible?

Yes

chemical equilibrium

reached when the forward and reverse reaction rates are equal

electronegativity

Electronegativity is an atom's ability to attract electrons in a covalent bond

What 3 things make an atom more electronegative

more protons in the nucleus, more electrons, and greater distance of the electrons from the nucleus

Electron transfer

happens when atoms are so electronegative that they strip electrons away from their bonding partner

Ion

created when electron transfer happens (atoms that have more or fewer electrons than protons)

Anion

negatively charged

Cation

positively charged

Ionic bond

electrical attraction between the charges of anions and cations

Ionic compounds

often called salts; can be strong but are weaker in polar solvents such as water

covalent bond

sharing of a pair of valence electrons in an attempt to complete valence shells and create stable molecules, strong bond

single covalent bond

two atoms share on pair of electrons (2 electrons total)

double covalent bond

two atoms share two pairs of electrons (4 electrons total)

nonpolar covalent bond

atoms have similar electronegativities and share the electrons equally; ex: h2, o2, ch4

Polar covalent bond

atoms have different electronegativities and share electrons unequally; ex: h2o, nh3

weak chemical bonds

dynamic and reversible

van der waals interactions

occur when transiently positive and negative regions of molecules attract each other

Water

molecule that supports all life

hydrophilic

affinity for water, ions, polar molecules

hydrophobic

fear of water, noncharged and nonpolar molecules such as fats and oils

4 emergent properties of water

high heat capacity, heat of vaporization, cohesion of water molecules, water’s versatility as a solvent

Water’s high heat capacity

high specific heat, moderates temperature (absorbs heat and releases to cooler air)

What unit is heat measured in

calories

How many calories are in a kilocal

1000 calories

Water’s heat of vaporization

water needs 586 calories to turn into a gas

cohesion of water molecules

cohesion is due to hydrogen bonding

Surface tension

measure of how hard it is to break the surface of a liquid; related to cohesion

adhesion

attraction between water molecules and other molecules; water clings to walls of vessels or tubes - capillary action

Water’s versatility as a solvent

due to it’s polarity, can form aqueous solutions of large variety of charged and polar solutes

The solvent of life

water - different regions of the polar water molecule can interact with ionic compounds and dissolve them

A mole

represents an exact number of molecules; the mass of 1 mole of a substance is determined by atomic mass

Avogadro’s number

1 mole = 6.022 × 10²³ molecules

Know how to do stoichiometry

ok

Milli-

1000 ex: 1000 milliliters in 1 liter

Micro-

million ex: 1 million microliters in a liter

Water can dissociate into

hydronium ions and hydroxide ions - changes in the concentration of these ions affect biological chemistry

an acid

is any substance that increases the hydrogen ion concentration of a solution

a base

is any substance that reduces the hydrogen ion concentration in a solution; some bases reduce H+ directly by accepting hydrogen ions

What is the product of H+ and OH- concentrations constant at

10^-14

The PH of a solution is determined by

the concentration of hydrogen ions

The PH levels in an acid are…

less than 7

Neutral solutions have a PH of…

7

Basic solutions have a PH…

greater than 7

Buffers

are substances that minimize changes in the concentration of hydrogen and hydroxide ions in a solution; consist of weak acid-base pair that reversibly combines with hydrogen ions

Carbon

has 4 electrons in the valence shell; can form covalent bonds with up to 4 different atoms

Hydrocarbon chains

aliphatic hydrocarbons - methane, ethane, ethene

The electron configuration of carbon

gives it covalent compatibility with many different elements

Carbon chains can vary in

length, branching, double bond position and presence of rings

Hydrocarbons

are found in a cell’s organic molecules

Aromatic hydrocarbons

can form five and six-membered rings; single or double bonds may connect the carbons in the ring

Important hydrocarbon ring

Benzene

Hydrocarbon bonds

covalent bonds between hydrocarbons store energy and release it when burned

Isomer

molecules that have the same chemical formula but differ in placement/arrangement of atoms or types of bonds

Structural isomers have

a different covalent arrangement

Geometric isomers have

a different arrangement around a double bond

enantiomers

differ in 3D placement of atoms

Types of enantiomers

D-alanine and L-alanine and only the L forms are used to make proteins

What industry are enantiomers used in?

The pharmaceutical industry