Chapter 1 & 2 Flashcards
What are the 7 characteristics of all living things?
- organization and cells
- responds to stimuli
- homeostasis
- metabolism
- growth, development and cell specialization
- reproduction
- change through time
What is homeostasis?
the maintenance of stable internal conditions even when conditions change (temperature, water content, blood glucose level, nutrients, etc).
What are the three domains of all living things?
bacteria, archaea, and eukarya
What are the six kingdoms that the three domains are divided into?
archaea, bacteria, protista, fungi, plantae, and animalia
What is an atom?
a substance that cannot be broken down into any other substance and continue to have the same properties
How many elements are are important to living things?
<30%
What are the four elements 90% of living organisms composed of?
oxygen, carbon, hydrogen, and nitrogen
What are the three parts of the atom (subatomic particles)?
proton, neutron, electron
What is the charge of a proton and where is it found?
+, nucleus of atom
What is the charge of a neutron and where is it found?
there is no charge, nucleus of atom
What is the charge of an electron and where is it found?
-, high energy particles that are in constant motion moving in an electron cloud around the nucelous
What does the number of protons tell about an element?
it’s atomic number
Can the number of neutrons vary from one atom of an element to another?
yes
What are the electron’s distance from the nucleus based on?
energy levels called orbitals
What energy levels do electrons fill first?
the lowest level
What determines the chemical characteristics of an element?
the number and location of the electrons
What are isotopes?
atoms of the same element with different numbers of neutrons
What is a chemical compound?
a substance formed by the chemical combination of 2 or more elements
What do chemical formulas tell?
which elements are present in a compound and their ratio
What are valence electrons?
electrons farthest away from the nucleus that are involved in forming chemical bonds
When do chemical bonds form between two atoms?
when valence electrons move between them either by being transferred or shared between atoms
When are covalent bonds formed?
when valence electrons are SHARED between atoms (ex: sodium chloride or salt)
How many electrons can atoms share?
1-3
When are ionic bonds formed?
when 1 or more valence electrons are TRANSFERRED from one atoms to another
What atoms become positively charged when ionic bonds are formed?
atoms that lose electrons
What atoms become negatively charged when ionic bonds are formed?
atoms that gain electrons
What are these newly positive and negative atoms called?
ions that are attracted to each other
What are chemical reactions?
a process that changes one set of chemicals into another set of chemicals
reactants to prodcuts
What do reactions involve?
the breaking of chemicals bonds and the formation of new ones
What is released energy usually?
heat
How is energy used?
either by being released or absorbed
What must every organism have to carry out their chemical reactions?
a source of energy
plants use sun
animals eat
What is activation energy?
the energy needed to get a chemical reaction started
Why is a catalyst needed for some chemical reactions?
they speed up the rate of the reaction by lowering the activation energy because some chemical reactions are too slow or have high activation energies that are not practical for living tissues
What are enzymes?
a protein catalyst used to speed up chemical reactions inside of living organisms
What do call catalysts have in common?
they aid specific chemical reactions but are not permanently changed or destroyed in the process
Why is life on earth water based?
all living cells contain water or are surrounded by water
Why is water important to life?
living cells are primarily composed of water, chemical reactions in cells take place in water, water helps transport nutrients and waste, water helps regulate body temperature, maintain cell shape an size, maintain the shape of proteins, and it’s necessary for all digestive, absorption, circulatory and excretory functions, water helps us utilize soluble vitamins
Why does solid H2O float?
it’s less dense than liquid H2O
What are the properties of water?
exists as solid, liquid, and gas
high specific heat
polarity
universal solevent
How does water absorb/release large amounts of energy?
it absorbs/releases it in the form of heat with only a slight change in its temperature
What are polar molecules?
molecules with covalent bonds that do not share the electrons equally
Why are water molecules polar?
their hydrogen end is slightly positive and the oxygen end is slightly negative
What is cohesion?
when water molecules stick to each other and create surface tension
What is adhesion?
when polar molecules stick to other polar molecules or other polar substances
What is capillarity?
the attraction between molecules that results in the rise of a liquid when in contact with a small tube
What are hydrogen bonds?
attraction of positive hydrogen of one molecule to the negative oxygen of another that from between the polar water molecules
What gives water its ability to exhibit cohesion, adhesion, and capillarity?
it’s polarity that allows hydrogen bonds to form
Why is water the universal solvent?
other polar molecules and ionic compounds dissolve in water
What substances do not dissolve in water?
nonpolar substances such as fats and oils
When do solutions form?
when a solute dissolves in the solvent
When is suspension formed?
when materials do not dissolve in water but stay suspended b the movement of water molecules
What are acids?
solutions with more hydrogen ions (H+) than hydroxide ions (OH-)
What are bases?
solutions with more OH- than H+
What is the pH scale?
a measurement system ranging from 0-14 that is sued to indicate the H+ concentration in solution
What is the neutral pH level?
7 (pure water)
What is an acidic pH level?
below 7
What is a basic/alkaline pH level?
above 7
What does each step on the pH scale reflect in the number of H+ ions
an a10-fold change
What is a buffer?
a weak acid or base that can react with strong acids or bases in order to control the pH
What do buffers in the human body maintain the pH level of most cells?
between 6.5 and 7.5
