Questions from Princeton Review MCAT Workout book and Practice Exams

Question 1

Which of the following is used to regulate prokaryotic transcription?

I. Pribnow box
II. Promoters
III. TATA box

a) I and II only
b) I and III only
c) II and III only
d) I, II, and III

Answer 1

a) both are present in prokaryotes.

TATA box is only present in eukaryotes and archaea

Question 2

Which enzyme finds the origin on a DNA molecule and unwinds the helix at that point?

Answer 2

helicase

Question 3

The primary role of [prokaryotic] DNA __________ _ is to slow down the work of other polymerases when mistakes have been detected and need to be corrected.

Answer 3

polymerase IV

p. 102

Question 4

If DNA polymerase I became non-functional, the bacterial genome would contain both ___ and ___. It is responsible for 5’ to 3’ ___________ activity, thus it removes the primers, which are composed of RNA.

Answer 4

RNA and DNA

exonuclease

p. 102

Question 5

The anticodon UAC is complementary to the codon AUG which codes for __________, the first amino acid used in translation.

Answer 5

methionine

Question 6

What is an auxotroph?

Answer 6

a bacterium that has lost the ability to synthesize a compound

Question 7

Prions lack a ______ and are considered “sub-viral” particles.

Answer 7

genome

Question 8

Some prions can be _________ through mutations that code for misfolded proteins.

Answer 8

inherited

Question 9

In children with Down syndrome, one of the primary cardiac defects is a _______ __________, which presents as a common arterial trunk coming off both the left and right ventricles. This allows for mixing of blood from the left and right circulations. Since the right circulation is relatively high in carbon dioxide and the left circulation is relatively low in carbon dioxide, the resultant mix will be somewhere between. By similar reasoning, the right circulation that is typically low in oxygen will mix with the left circulation that is typically higher in oxygen, so the overall aortic arterial oxygen saturation will be ____ than normal and the pulmonary arterial oxygen concentration will be ______ than it is normally. Since a common arterial trunk is receiving blood from both the right and left ventricles, the pulmonary artery will be receiving more blood than usual and therefore will have pulmonary ___________.

Answer 9

truncus arteriosus
lower
higher
hypertension

Question 10

The _____-________ equation can only be used to describe the frequencies of autosomal reces­sive or dominant traits or conditions, not changes in chromosome number. Since trisomies are not autosomal recessive conditions, the Hardy-Weinberg equation cannot be used, and one cannot predict the occurrence of the carriers in a population. Also, because trisomies are not based on dominant or recessive expressions, there is no “_______” state.

Answer 10

Hardy-Weinberg
carrier

Question 11

During spermatogenesis, spermatids have already undergone ______ ___________.

Answer 11

meiotic recombination

Question 12

Passage: “Fluorescent in situ hybridization (FISH) is a molecular genetics laboratory technique where fluorescently labeled probes are hybridized to fixed chromosome clusters.”

What should the probe be made of?

Answer 12

a segment of single-stranded DNA which is complementary to the gene being studied, covalently linked to a fluorochrome.

It must be single-stranded bc the point of FISH, is that complementary bases “find each other” and hybridize.

(From Princeton Review Practice Exam 1)

Question 13

The usual process to produce proteins follows these steps: cytoplasm -> endoplasmic reticulum -> Golgi apparatus -> cell membrane.

According to the passage, Arf1 is responsible for the retrograde transport for the Golgi. Thus, the cellular membrane would represent the forward step, not the backward (retrograde) step.

Question 14

The cutting of introns and the splicing associated with the expression of the Factor VIII genes occur during which step in the protein-synthesis process?

Answer 14

DNA → mRNA
Splicing is part of the post-transcriptional process: DNA is first transcribed in primary transcript and then modified to become mRNA.

(Free AAMC Practice Exam)

Question 15

In oxidative phosphorylation, cytochrome c acts as:

A. a 1-electron carrier.
B. a 2-electron carrier.
C. a 3-electron carrier.
D. a 4-electron carrier.

Answer 15

A.
Cytochrome c is a heme protein that cycles between a ferrous (Fe+2) and ferric (Fe+3) state during oxidative phosphorylation. Therefore, only a single electron is transferred in the process.

(Free AAMC Practice Exam)

Question 16

Which primer is most suitable for PCR?

A. 5’–ATTACGTTAACATGAAG–3’

B. 5’–ATATCGTTAACAAATTG–3’

C. 5’–GCTATAAAGATTGCAAA–3’

D. 5’–GCATAGAAGCATTCCGC–3’

Answer 16

D.

Best primers for PCR have a high GC content and CG bases at the 5′ and 3′ ends. Only answer D has a G or C at the beginning and the end of the strand.

Question 17

In which phase of meiosis does nondisjunction occur?

Answer 17

Anaphase I

Question 18

Which feature of the kinetics of L-alanine transport would provide evidence that DOM is an important source of nutrients under low-food conditions?

A. High-affinity transport (Kt) of L-alanine
B. Low-affinity transport (Kt) of L-alanine
C. High transport capacity (Jmax) of L-alanine
D. Low transport capacity (Jmax) of L-alanine

Answer 18

A.
Under low-food conditions, where nutrients are at low concentrations, only the high affinity transporters of L-alanine would be able to facilitate its binding and uptake.

Question 19

If the concentration of amino acid transport protein is increased, the transport affinity Kt of L-alanine will:

A. level off rapidly.
B. decrease.
C. not change.
D. quickly reach the maximum value.

Answer 19

Transport affinity for substrates (in this case, alanine) is an inherent property of transport proteins, and thus transport affinity is independent of the concentration of transport protein.

Question 20

For transporters the transport affinity (K_t) is equivalent to the K_M in Michaelis–Menten kinetics. This means that K_t is the substrate concentration at which the reaction rate is one-half the _______ transport capacity.

Answer 20

maximal

Question 21

Actin is a type of…..

Answer 21

…microfilament.