Exam 1 - Biology

8 characteristics of life

1. order/organization

2. sensitivity to or response to the environment

3. reproduction

4. adaptation

5. growth and development

6. regulation/homeostasis

7. energy processing

8. evolution

order/organization

biology occurs at many levels which is how their complex nature is examined

cells

smallest unit of organization and perform all activities required for life

cells are classified by

eukaryotic and prokaryotic

eukaryotic

membrane enclosed organelles, largest is typically the nucleus

prokaryotic

doesn’t contain nucleus or other membrane enclosed organelles, simpler than eukaryotes (remember: pro means no nucleus)

tissues

groups of similar cells carrying out similar or related functions

organs

collections of tissues grouped together performing a common function

organ systems

consists of functionally related organs

organism

individual living entities

population

all individual species living within a specific area

community

all populations inhabiting a specific area (only living)

ecosystem

consists of all living things and nonliving (abiotic) environment in a particular area

biosphere

collection of all ecosystems

sensitivity or response to the environment

organisms respond to a diverse stimuli

reproduction

single and multicellular organisms can reproduce via cell division, which passes genes off to the offspring

adaptation

living organisms ability to adjust or fit into their environment (short-term)

growth and development

occurs because genes provide instructions to do so

regulation/homeostasis

living organisms require multiple regulatory mechanisms to coord internal functions, respond to stimuli, and cope with enirvnmental stresses

homeostasis

process by which organisms maintain internal conditions

energy processing

organisms use a source of energy for their metabolic activities

evolution

(via natural selection) allows organisms to adapt to their environment as it changes (long-term)

stabilizing selection

natural selection favors an average and selects against extreme variation

directional selection

follows environmental change and favors one end of the spectrum

diversifying selection

when natural selection favors BOTH extremes over the average

hypothesis

a testable possible explanation for an event that must also be falsifiable, meaning it can be disproved by the results.

variables

parts of the experiment that can change or vary throughout

experimental group

manipulated by the scientists

control group

unmanipulated reference

hypothesis is supported if

the experimental group does not equal the control group

matter

any substance that takes up space and has mass

atoms

smallest unit of matter that form all chemical substances - building blocks of elements

elements

unique forms of matter with specific chemical and physical properties that cannot be broken down into smaller substances

trace elements

only required in very small quantities

compounds

form when two or more elements are bonded together

the two regions of the atom

nucleus region and orbital region

nucleus region

atom’s center and contains protons and neutrons

orbital region

holds the atom’s electrons in orbit around the nucleus

mass number

number of protons plus the number of neutrons (always a whole number)

protons and neutrons weigh about the same: 1.67×10^-24 which is called

one atomic unit or one dalton

atomic number

number of protons

isotopes

different versions of the same element that have the same number of protons but a different number of neutrons

atomic mass

similar to mass number, but takes into account all of an atom’s isotopes and their relative abundances (how many atoms of that isotope exist)

periodic table

groups elements by their chemical properties

shells

region of space surrounding the nucleus where you find electrons

orbitals

specific regions within a shell

order in which electrons fill shells

innermost orbital (2 electrons) → next two shells in order (8 electrons each)

valence shell

outermost electrons orbital of an atom

octet rule

atom is most stable energetically when they have a full valence shell

how many electrons hydrogen needs for a full valence shell

2

the less electrons an atom has in a valence shell, the more likely it is to

bond

inert or noble gases

elements that have full valence shells and are highly stable (they don’t bond)

molecule

chemical structure resulting from 2 or more atoms that have chemically bonded with each other

molecular formula

contains chemical symbols of the elements in the molecule

chemical reaction

when 2 or more atoms bond to form molecules or when bonded atoms break apart

three types of bonds

1. ionic

2. covalent

3. hydrogen

ionic bond

electrons are transferred, forming ions that are attracted to each other

ion

an atom that is more stable once it has gained or lost an electron

cation

positive ions that form by losing electrons

anion

negative ions that form by gaining an electron

ionic compounds are called

salts

covalent bond

electrons are shared to fill valence shells (can be polar or nonpolar)

polar covalent bond

atoms unequally share electrons and are more attracted to one nucleus than the other (creates a slightly positive or slightly negative charge)

nonpolar covalent bond

form between two elements and share electrons equally (no charge difference)

hydrogen bond

hydrogen atom from one polar molecule is attracted to an electronegative atom from another molecule

hydrophilic

polar molecule that interact readily or dissolves in water (water loving)

hydrophobic

nonpolar molecule that doesn’t interact well with water (water hating)

heat

measure of the total kinetic energy due to molecular motion (more movement → more kinetic energy → more heat)

excess molecule movement creates kinetic energy (heat) which causes

the bonds to break and causes a liquid to change to a gas

ice floats because

water as a solid is less dense than liquid (more open crystalline structure)

4 properties of water

1. high heat capacity

2. high heat of vaporization

3. solvent

4. cohesion and adhesion

specific heat

the amount of heat one gram of a substance must absorb to change its temp by 1 degree C

high heat of vaporization

amount of energy required to change one gram of a liquid substance to a gas (high for water)

evaporative cooling

energy is taken up during evaporation, cooling the surrounding environment

solvent

substance capable of dissolving other polar molecules and ionic compounds

solute

any component dissolved in a solvent

solution

homogenous mixture of one or more solutes dissolved in a solvent

sphere of hydration

charges associated with solvents and solutes that will form hydrogen bonds with water, which surrounds the particle with water molecules

dissociation

occurs when atoms or groups of atoms break off from molecules and form ions

surface tension

capacity of a substance to withstand rupturing when placed under tension or stress

adhesion

attraction between water molecules and other molecules

cohesion

water molecules are more attracted to each other than the surrounding air

capillary action

water molecules are more attracted to charged glass tube than other water molecules and “climb” up the tube (water transport in plants)

pH

indicates acidity or basicity of a solution

acid

substances that increase the H+ concentration of a solution (high concentration of H+ → high acidity → low pH)

base

substances that reduce the H+ concentration of a solution (low concentration of H+ → low acidity → high pH)

pH scale ranges from

0-14
>8 → basic
+7 → neutral
<7 → acidic

buffer

substances that minimize changes in the concentration of H+ and OH- in solutions