BIO 110 first exam
DNA and RNA contain monomer units known as
nucleotides
If 2 atoms are joined by a polar covalent bond, the shared electrons will tend to stay closer to the atom with which of the following characteristics?
The higher electronegativity
A(n) __________________ covalent bond involves EQUAL sharing of one or more pairs of electrons.
nonpolar
High heat of vaporization
organisms swear or pant to cool themselves
Water is less dense as a solid than as a liquid
aquatic organisms can survive below the frozen surface of ponds and lakes
The ability of water to rise inside a tube of narrow diameter against the pull of gravity is called ______________ action.
capillary
Cl = e- -> is an example of
reduction
Lipids are the only class of macromolecules that contain
fatty acids
Carbohydrates are composed of
monosaccharides
How do ions in a crystal matrix interact?
each ion is attracted to all of the oppositely charged ions in its vicinity
Atoms differ in their affinity for ________, a property called electronegativity.
electrons
In living organisms, almost all chemical reactions are catalyzed by protein catalysts called ____________.
enzymes
The angle between the 2 O-H covalent bonds in a molecule of water is how many degrees?
104.5
In a double covalent bond, _________________ total electrons are shared.
4
If an atom has 4 electrons in its outermost energy level, how many covalent bonds must it form in order to have a stable outer shell of electrons?
4 (octet rule)
Why are molecules formed by 2 hydrogen atoms (H2) stable?
It has no net charge it is held together by a covalent bond it has no unpaired electrons
Strongest to weakest: double covalent, hydrogen, triple covalent, single covalent
Triple covalent double single hydrogen
Relatively small organic molecules with a central carbon atom which is bonded to a carboxyl group, an amino group, a carbon containing group, and a hydrogen atom are called:
amino acids
How does the partial charge of a polar covalent bond compare to the unit charge of an ion?
a partial charge is far smaller than a unit of charge
Phospholipids are made up of
a phosphate, two fatty acids and a glycerol.
the attraction of water to other polar substances is called ________.
adhesion
Proteins are polymers formed of monomers called
amino acids
hydrogen bond
attraction between a covalently bound H atom with a slight positive charge & another covalently bound atom with a slight negative charge
Ionic bond
attraction between oppositely charged atoms
Humans are unable to get metabolic energy from cellulose because
cellulose digesting enzymes are absent from the human body
Because polar water molecules attract each other, water is said to be ___________.
cohesive
A substance composed of atoms of more then one element that are held together by chemical bonds is called?
compound
When two atoms share a pair of electrons, the bonding is referred to as
covalent
bonds and interactions form strongest to weakest
covalent ionic hydrogen hydrophobic interaction Van der Waals attraction
strongest to weakest
covalent bonds ionic bonds hydrogen bond hydrophobic interaction Van der Waals attraction
Biological membranes contain bilayers containing mostly
phospholipids
Cohesion
plant leaves pull water up from the roots
A(n) _____________ covalent bond is formed by unequal sharing of one or more electron pairs.
polar
Because oxygen is more electronegative than hydrogen, the water molecule is
polar
Amino acids are linked together by condensation reactions to form a
protein
By convention, when writing a chemical equation the ____________ are listed on the left side of the arrow and the _____________ are listed on the right side of the arrow.
reactants ; products
Which is non polar? H2O, CH4, O2, N2?
CH4, O2, N2. ALL EXCEPT WATER.
High specific heat
water stabilizes the temperature of organisms and the environment
van der Waals attraction
weak attraction between atoms due to oppositely polarized electron coulds
A(n) _________________ is made of 2 or more atoms held together by chemical bonds in a stable association. The atoms may or may not belong to the same element.
molecule
a group of atoms held together by chemical bonds in a stable association is what?
molecule
carbohydrates are polymers formed by monomers called
monosaccharides
hydrophobic interaction
nonpolar regions of a molecule are forced together in order to minimize contact with water molecules
A chemical reaction involves the breaking and formation of _______________ ______________.
Chemical Bonds
Water consists of one oxygen atom joined by two hydrogen atoms by what type of bonds?
Covalent
What type of bond is formed when 2 atoms share one or more pairs of valence electrons?
Covalent
Macromolecules that are used to store hereditary information are called
DNA molecules
In living systems, ionic compounds generally exist as ionic crystals?
FALSE- solids
Unlike covalent bonds, which produce a crystal lattice, ionic bonds are formed between 2 individual atoms, giving rise to true, discrete molecules?
False, covalent bond have discrete molecules which ionic form a crystal lattice
Order the following atoms in increasing order of their electronegativity, starting at the top with the LEAST electronegative one. (C,H,O,N)
H C N O
What type of bond forms between 2 hydrogen atoms?
Nonpolar covalent
What characteristic would the R groups of amino acids have if they are located within the interior of biological membranes?
The R groups would be hydrophobic
The surface tension of water is due to?
The cohesion of water molecules
Water rises inside a glass tube with narrow diameter for which reason?
There are electrical charges on the surface of the glass and water molecules adhere to the surface of the glass
True statements about polar molecules:
They are attracted to other polar molecules They have the same # of protons and electrons They are electrically neutral
The covalent bonds connecting monomer units in sugars can be formed by the removal of a water molecule. This reaction is referred to as
a dehydration reacrion
Macromolecules are often defined by _________ such as -OH and -NH2 that affect their chemical properties
functional groups
one energy storage macromolecule made by animals is called
glycogen
Water molecules are polar with ends that exhibit partial positive and negative charges. These opposite charges allow water molecules to attract each other through
hydrogen bonds
Macromolecules are broken down to monomers in
hydrolysis reactions
A catalyst is any substance that ______________ the rate of a reaction without being altered itself.
increases
Bonds that form due to the attraction between oppositely charged atoms that have gained or lost electrons are called ____________ bonds.
ionic
In the crystal matrix of ordinary salt, the sodium and chlorine are held together by
ionic bonds
When atoms gain or lose electrons, they become negatively or positively charged. These negatively or positively charged atoms are known as
ions
Solubility
ions and molecules move freely in cells, permitting an array of chemical reactions
What does it mean when we say water is adhesive?
it is attracted to other polar molecules and ions
When writing out structural formulas, covalent bonds are represented by solid _______ between atomic symbiosis.
lines
Covalent bond
sharing electrons
Because of the many hydrogen bonds that form between its molecules water has a very high _______ _________. This allows small insects to "walk on water"
surface tension
The property of ___________ _____________ is a measure of how difficulty it is to stretch or break the surface of a liquid.
surface tension
hydrogen bonds are important because
they play a key role in determining the properties of water they help maintain the structure of DNA & proteins
THREE fatty acids bonded together with a glycerol is a
triglyceride
a common type of lipid used for energy storage are
triglycerides
