Download Practice Exam 2

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
____
27.
Isomers are molecules that
a.
react readily with one another
b. have the same molecular formula
c.
have different molecular masses
d. differ in the number of unsaturated bonds
e.
must contain the same functional group
____
28.
Choose the element that is found in all organic compounds.
a.
nitrogen
b. carbon
c.
sulphur
d.
e.
hydrogen
oxygen
____
29.
What name is given to compounds in which a carbon atom only bonds to hydrogen and other carbon atoms?
a.
fatty acids
d. nucleic acids
b. hydrocarbons
e.
carbohydrates
c.
lipids
From the following list, which is an example of a monosaccharide?
a.
maltose
d. glucose
b. glycogen
e.
sucrose
c.
cellulose
____
30.
____
31.
When a molecule of glycerol reacts with one or more fatty acids an ester linkage results. The formation of this linkage is a result of a reaction between
a.
an amino acid and a carboxylic acid
d. two carboxylic acids
b. two alcohols
e.
two amino acids
c.
an alcohol and a carboxylic acid
____
32.
When two organic molecules are joined together and a water molecule is removed, the reaction is called which of the following?
a.
dehydration synthesis (condensation)
d. oxidation
b. hydrogenation
e.
reduction
c.
hydrolysis
____
33.
The hydrolysis (breakdown) of an ester results in
a.
a sugar and an acid
b. two acids
c.
an acid and an amine
d.
e.
two sugars
an acid and an alcohol
____
34.
The hydrolysis (breakdown) of a dipeptide results in the production of which of the following?
a.
a sugar and an amino acid
d. two sugars
b. two amino acids
e.
an amino acid and an alcohol
c.
an acid and an amine
____
35.
The extremely large diversity of structure seen in proteins is mainly due to
a.
the disulfide and hydrogen bonds that determine molecular shape
b. the action of the ribosomes
c.
the precise location of specific amino acids, common to all proteins
d. different numbers, kinds, and sequences of amino acids
e.
different kinds of bonds between successive amino acids
____
36.
An oxidation/reduction is best shown by which of the following?
a.
an amino and carboxyl group form a peptide bond
b. two small molecules chemically combine to form a large one
c.
a base reacts with an acid to form water and a salt
d. electrons are transferred from one substance to another
e.
a large molecule is broken into two smaller molecules
____
37.
In the following, what kind of chemical reaction is shown?
R-CHO + H2O + NAD+  R-COOH + NADH + H+
a.
deamination
b. hydrolysis
c.
dehydration synthesis (condensation)
d.
e.
neutralization
oxidation/reduction
____
38.
During photosynthesis, water molecules are split according to the following reaction:
H2O + NADP+  NADPH + H+ + O2
In the reaction, which substance undergoes reduction?
a.
the hydrogen ions (protons)
d. the NADP+
b. the NADPH
e.
the water molecules
c.
the oxygen that is released
____
39.
In most cellular processes, oxidation involves
a.
the loss of oxygen atoms
b. free oxygen
c.
the gain of hydrogen atoms
d.
e.
the gain of electrons
the loss of hydrogen atoms
____
41.
Which of the following statements about enzymes is not true?
a.
They are proteins with tertiary or quaternary structures.
b. They are very specific for the substrate to which they bind.
c.
They will bind their substrate and any isomer of their substrate.
d. Their names usually end in 'ase.'
e.
All of the above statements are true.
____
42.
Which of the following statements regarding enzyme inhibition is incorrect?
a.
Competitive inhibitors have a similar structure to the normal substrate.
b. Competitive inhibitors bind to the active site of an enzyme.
c.
Noncompetitive inhibition can be overcome by adding more substrate.
d. Noncompetitive inhibitors do not have a similar structure to the normal substrate.
e.
Noncompetitive inhibitors do not bind to the active site of an enzyme.
____
43.
Which of the following statements concerning allosteric regulation is not true?
a.
Allosteric sites are usually located next to, but separate from, the active site.
b.
c.
d.
e.
Alosterically controlled enzymes usually have quaternary structure.
'Activators' tend to keep all the active sites available to the normal substrate.
'Allosteric inhibitors' stabilize the inactive form of the enzyme.
Allosteric regulators attach to their sites using weak bonds.
____
44.
Which of the following is not an application of enzymes for commercial or industrial use?
a.
starch hydrolysis for the food industry
b. proteases to coagulate milk for the manufacture of cheese
c.
removal of lactose from dairy products for lactose intolerant people
d. lipases added to crude oil before being processed into plastics
e.
proteases added to detergents to remove protein-based stains
____
45.
During aerobic cellular respiration, which of the following is the most common type of reaction to take place in the cell?
a.
hydrolysis
d. redox
b. condensation
e.
dehydration
c.
neutralization
____
46.
The following molecules can be found at various stages during cellular respiration:
I.
acetyl-CoA
II.
carbon dioxide
III.
glucose
IV.
glyceraldehyde
V.
pyruvate
Which of the following sequences represents the above molecules in order from the largest to the smallest amount of chemical energy?
a.
II, I, V, IV, III
d. III, I, V, IV, II
b. III, IV, V, I, II
e.
IV, III, II, I, V
c.
III, IV, I, V, II
____
47.
What is the name of the process in which energy is released in a cell in the presence of sufficient oxygen?
a.
anaerobic respiration
d. glycolysis
b. aerobic respiration
e.
anabolism
c.
fermentation
____
48.
Proteins are to ribosomes as ATP is to which of the following cell organelles?
a.
centrioles
d. chromosomes
b. mitochondria
e.
nucleus
c.
Golgi apparatus
____
49.
During aerobic cellular respiration, which of the following molecules activates Krebs cycle?
a.
citrate
d. acetyl coenzyme A
b. pyruvate
e.
carbon dioxide
c.
cytochrome oxidase
____
50.
Anaerobic respiration is less efficient than aerobic respiration for which of the following reasons?
a.
less ATP is produced in anaerobic respiration
b. aerobic respiration allows for rapid oxidation during strenuous exercise
c.
blood carries more than enough oxygen to support aerobic respiration
d. only bacteria and yeast use anaerobic respiration
e.
most animals have to breathe air in order to survive
____
51.
When muscles cells do work under anaerobic conditions, the muscle cells
a.
use lactate to synthesize glycogen for glycolysis
b. use the pyruvate-acetyl-CoA shunt as an alternative energy source
c.
get their energy from oxidative phosphorylation instead
d. produce lactate and release energy that way
e.
stop functioning, which results in cramping
____
52.
Anaerobic and aerobic respiration are similar in all but one of the following ways. Which one is the exception?
a.
NAD+ is reduced
b. carbon dioxide is a product
c.
ADP is combined with inorganic phosphate to form ATP
d. acetaldehyde is converted into ethanol
e.
both can release energy from glucose
____
53.
Amino acids can enter cellular respiration, but first they have to be
a.
deaminated
d.
b. hydrolyzed
e.
c.
phosphorylated
converted to glucose
converted into protein
____
54.
Ethanol fermentation at a brewery is most likely limited by
a.
the availability of a carbohydrate source
b. the availability of ATP
c.
the build up of carbon dioxide
d. the build up of alcohol
e.
the availability of reductant
____
70.
During DNA replication, the function of RNA primers is to
a.
open replication bubbles
b. serve as starting points for DNA strand elongation by DNA polymerase I in the 3' - 5' direction
c.
serve as starting points for DNA strand elongation by DNA polymerase III in prokaryotes
d. prevent new-separated strands of DNA from rejoining
e.
serve as a binding site for DNA ligase
____
71.
If a free phosphate is found at the 5' end of a DNA strand, what is found at the other end of the same strand?
a.
a hydroxyl group on the 5' carbon of a deoxyribose sugar
b. a hydroxyl group on the 3' carbon of a deoxyribose sugar
c.
a phosphate group on the 5' carbon of a deoxyribose sugar
d. a phosphate group on the 3' carbon of a deoxyribose sugar
e.
a base attached to the 3' carbon of a deoxyribose sugar
____
72.
In their experiment that showed that DNA replication in E. coli was semi-conservative, Meselson and Stahl used
a.
a radioactive isotope of nitrogen
b.
c.
d.
e.
____
73.
nitrogen isotopes having different mass
ultraviolet light
radioactive phosphorus
nitrogen isotopes which had different numbers of protons
In DNA, phosphodiester bonds join
a.
two phosphate groups
b. bases and sugars
c.
phosphate groups and sugars
d.
e.
phosphate groups and bases
two sugar molecules
____
74.
A section of mRNA 9 codons long would most likely result in the addition of how many amino acids to a growing polypeptide (the stop codon is
absent from the section of mRNA)?
a.
9
d. 27
b. 5
e.
3
c.
10
____
76.
If transcription could proceed in both directions along both DNA strands of a gene, how many different polypeptides could be coded for by a single
gene?
a.
1
d. 4
b. 2
e.
none
c.
3
____
77.
There are differences in the amino acid sequence of rabbit and frog haemoglobin polypeptides. If mRNA for rabbit haemoglobin is extracted from
rabbit red blood cells, and is then placed in frog eggs, the cells will produce rabbit haemoglobin polypeptides. This shows that
a.
rabbit haemoglobin mRNA is the same as frog haemoglobin mRNA
b. the genetic code and the machinery of translation are substantially the same in widely-different organisms
c.
the gene for haemoglobin is identical in all organisms
d. the DNA for rabbit hemoglobin is reverse transcribed into DNA in the frog eggs
e.
frog ribosomes are incapable of binding to mammalian RNA
____
79.
If you were shown an electron micrograph of a cell in which mRNA was being translated while it was still being transcribed from the DNA, you would
know
a.
the gene product was in high demand at the point in the cell cycle at which the image was captured
b. the cell was prokaryotic
c.
transcription was occurring extremely fast
d. the electron micrograph showed the nucleus of the cell
e.
the cell was eukaryotic
Completion
Complete each sentence or statement.
178.
Carbohydrates are the most common organic materials of Earth. They contain carbon, hydrogen, and oxygen in a _________________________ ratio.
Carbohydrates are classified into three groups. The monosaccharides are partly classified by the number of carbons in their backbone. For example
five-carbon sugars are called _________________________ while six-carbon sugars are called _________________________. When two or three
monosaccharides join together they are called _________________________. The bond that links them together is called a(n)
_________________________ linkage. When only two sugars bond together they are called a _________________________. When several hundred
to several thousand sugars link together they are called a(n) _________________________. These substances are important either for energy storage
such as _________________________ or structural support such as _________________________.
179.
Lipids are a large group of hydrophobic molecules composed of carbon, hydrogen and oxygen. They are divided into four families: fats, phospholipids,
steroids and waxes. Fats are the most common _________________________ molecules in living things. The most common fats in plants and animals
are the _________________________. These contain _________________________ fatty acids and _________________________ molecule of
glycerol. Fatty acids are long hydrocarbon chains with a single _________________________ group at one end. Fatty acids can be either saturated, if
all the carbons have _________________________ single bonds, or unsaturated if they have one or more carbon-carbon double bonds. When glycerol
reacts with a fatty acid a(n) _________________________ linkage is formed along with the production of _________________________. The
membranes of cells are composed of phospholipids, molecules in which one of the fatty acids has been replaced by a(n) _________________________
group which is _________________________ polar and therefore very _________________________ with respect to water. The sterols contain four
fused hydrocarbon rings and several different functional groups. One of the most well known sterols is _________________________, which is
important in cell membrane structure, but has been linked to atherosclerosis. Waxes contain long-chain fatty acids linked to alcohols or carbon rings.
They are good water-proofing substances. An example in plants would be _________________________, which forms a water-resistant coating on
leaves.
180.
The process of glycolysis occurs in the ____________________ and begins with a molecule of ____________________. Glycolysis is a(n)
____________________ process, as it does not require oxygen. Glycolysis is a ten step process the highlights of which involve
____________________ molecules of ATP being used to "prime" the beginning portion of the pathway. Fructose 1,6-bisphosphate is split into
____________________ carbon units. Each of these units reacts in the same way and ____________________ NADH are produced in total. ATP
production involves a total of ____________________ molecules from substrate level phosphorylation for a net production from glycolysis of
____________________ ATP.
183.
After transcription, the first-formed mRNA is modified in eukaryotic cells. A ____________________ is added at the 5' end and a
_____________________ made up of many ____________________ nucleotides is added at the 3' end.
Matching
Match each item with the correct statement below.
a.
London dispersion
b. polar covalent bonds and symmetrical structure
c.
intermolecular
d. hydrophobic
e.
van der Waals forces
f.
hydrogen bond
g. polar covalent bonds and asymmetrical structure
h. intramolecular
i.
hydrophilic
j.
dipole-dipole
____
201.
What are bonds between molecules called?
____
202.
What dipole-dipole force results between H and either N, O or F?
____
203.
What is a property of polar molecules?
Match each item with the correct statement below.
a.
catalysts
b. catabolic
c.
chemoautotrophs
d. anaerobic cellular respiration
e.
aerobic cellular respiration
f.
photoautotrophs
h.
i.
i.
j.
k.
l.
____
204.
What organisms use light energy to build organic compounds?
____
205.
What organisms consume other organisms for chemical energy?
____
206.
What organisms build organic compounds without using light?
____
207.
What process releases energy from organic compounds using oxygen?
____
208.
What lowers the activation energy in cellular reactions?
____
209.
What type are most of the reactions that occur in cellular respiration?
anabolic
enzymes
heterotrophs
Redox (oxidation/reduction)
hydrolysis
Match each item with the correct statement below concerning the Krebs cycle.
a.
1
f.
6
b. 2
g. ATP
c.
3
h. GTP
d. 4
i.
acetyl-CoA
e.
5
j.
pyruvate
____
212.
What molecule, derived from glycolysis, is at the start of the cycle?
____
213.
how many times does decarboxylation occur?
____
214.
How many NADH are produced in each turn of the cycle?
____
215.
How many FADH2 are produced in each turn of the cycle?
____
217.
How many carbons are in oxaloacetate at the beginning of the cycle?
Match each item with the correct statement below.
a.
template strand
b. ligase
c.
primase
d. DNA polymerase I
e.
lagging strand
f.
replication fork
g. semi-conservative replication
h. Okazaki fragment
i.
j.
k.
l.
m.
n.
o.
single-stranded binding proteins
leading strand
gyrase
helicase
annealing
mitosis
DNA polymerase III
____
221.
process which results in each new DNA molecule consisting of one parental strand and one newly synthesized strand
____
222.
unwinds DNA
____
223.
new DNA strand synthesized in fragments
____
224.
division of a nucleus to form two daughter nuclei
____
225.
short lengths of DNA produced during synthesis of lagging strand
____
226.
keep newly separated strands of DNA apart
____
227.
new DNA strand which is synthesized continuously
____
228.
links sugars and phosphates together
____
229.
area where DNA polymerase is bound to unwound DNA
____
230.
DNA strand which directs synthesis of a complementary strand
____
231.
builds RNA primers
____
232.
relieves tension in DNA during unwinding
____
233.
pairing of complementary strands of DNA due to hydrogen bonding
____
234.
responsible for building new DNA strands during replication