o chem practice exam 3

Question 1

Which of the following fatty acids is most likely to be a liquid at room temperature?

Answer 1

A

Question 2

Consider the statements below and choose the letter that describes them all:
(1) Cholesterol is both a steroid and a membrane lipid.
(2) Waxes are made from sphingosine and a long chain alcohol.
(3) Sphingolipids are components of cell membranes.

Answer 2

Statements (1) and (3) are true.

Question 3

The following reaction would most likely be catalyzed by an enzyme of which class?

Answer 3

isomerase

Question 4

Chemical messengers can interact with receptors through

A) hydrogen bonds
B) electrostatic interactions
C) hydrophobic interactions
D) all of the above
E) none of the above

Answer 4

All of the above

Question 5

Which choice is an example of passive transport across a cellular membrane?

A) passing protons through the proteins against a concentration gradient
B) oxygen passing directly through a membrane
C) K+ passing through an ion pump fueled by the energy from ATP
D) cholesterol interacting with hydrophobic portions of glycerolphospholipids
E) none of the above

Answer 5

B

Question 6

Adding a phosphate group to the active site of an enzyme to reversibly block the active site is an example of using _______________________ to control enzyme activity.

A) covalent modifications
B) feedback control
C) specificity
D) genetic regulation
E) hydrolysis

Answer 6

covalent modifications

Question 7

Enzymes are catalysts because they

A) change the value of the free energy change to a more favorable value.
B) change the value of the equilibrium constant to a more favorable value.
C) lower the value of the activation energy.
D) increase the amount of time needed to reach equilibrium.
E) become one of the reactants.

Answer 7

lower the value of the activation energy.

Question 8

The following reaction would most likely be catalyzed by enzymes of which class?

Answer 8

hydrolase

Question 9

What class of chemical messenger does the following molecule belong

Answer 9

Bile salt

Question 10

9. What class of chemical messenger does the following molecule belong

Answer 10

adrenergic

Question 11

Which statement is true regarding chemical messengers?

A) Chemical messengers catalyze reactions to turn on enzyme activity.
B) Chemical messengers bind to receptors irreversibly.
C) The endocrine and nervous systems utilize chemical messengers to maintain homeostasis.
D) Chemical messengers cannot affect protein synthesis.
E) None of these are true

Answer 11

c

Question 12

Which of the following is the typical shape of a plot showing the rate of an enzyme-catalyzed reaction as a function of substrate concentration

Answer 12

B

Question 14

Which of the following is the typical shape of a plot showing the rate of an enzyme-catalyzed reaction as a function of Ph concentration

Answer 14

D

Question 15

11. Which of the following is the typical shape of a plot showing the rate of an enzyme-catalyzed reaction as a function of enzyme concentration

Answer 15

A

Question 16

12. How many H2 molecules are necessary to completely hydrogenate the following molecule?

Answer 16

3

Question 17

13. The molecule shown can be classified as a(an

Answer 17

Glycerophosoplid

Question 18

14. The molecule below is the substrate for the enzyme malate dehydrogenase.

Answer 18

C

Question 19

15. Which of the following enzymes associated with DNA replication is paired with its correct function?

A. DNA helicase; connection of Okazaki fragments
B. DNA polymerase; formation of phosphodiester linkages
C. DNA ligase; unwinding of the DNA helix
D. more than one correct response
E. no correct response

Answer 19

B

Question 20

16. When a mature mRNA is made from the DNA strand shown, its base sequence will beComplementary (coding) strand of DNA: 5’ TTACGGAT 3’
    Template strand of DNA: 3’ AATGCCTA 5’

A) 5’ TTACGGAT 3’.
B) 5’ AACUA 3’.
C) 5’ UUACGGAU 3’.
D) 5’ AAUGCCUA 3’.
E) 5’ UUGAU 3’

Answer 20

c

Question 21

17. Sickle cell anemia is an example of a disease caused by an SNP, single nucleotide polymorphism, because …

A) it is caused by the deletion of a single nucleotide and is common in a given population.
B) it is caused by the insertion of a single nucleotide and is common in a given population.
C) it is caused by a point mutation and is common in a given population.
D) it is caused by a point mutation and is specific to an individual.
E) it is caused by a point mutation.

Answer 21

C

Question 22

18. Which of the following is a coding portion of a DNA molecule (i.e. it codes for a protein)?

A) telomere
B) centromere
C) exon
D) intron
E) promoter sequence

Answer 22

C

Question 23

19. The molecule below is

A) a nucleoside that contains a purine.
B) a nucleoside that contains a pyrimidine.
C) a nucleotide that contains a purine.
D) a nucleotide that contains a pyrimidine.

Answer 23

A

Question 24

22. All of the statements about RNA are true except

A) RNA can exist in multiple forms including: rRNA, tRNA, and mRNA.
B) RNA molecules are synthesized by RNA polymerase.
C) Hydrogen bonding between bases is not important to RNA translation.
D) Transfer RNA delivers amino acids for the protein chain as it is being manufactured.
E) mRNA contains the instructions to make peptide chains.

Answer 24

C

Question 25

23. The translation occurs in the ________.

A) mitochondria
B) cytosol
C) ribosome
D) Golgi apparatus
E) nucleus

Answer 25

C

Question 26

24. Recombinant DNA is the process of

A) combining two genes into a new piece of DNA that does not exists in nature.
B) copying DNA using DNA polymerase.
C) using the chromosome from one species to express proteins.
D) introducing mutations to treat a disease caused by an overactive protein.
E) cross breeding two closely related species to produce a hybrid.

Answer 26

A

Question 27

Answer 27

Question 28

Answer 28