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MCAT! > Biology/Biochemistry > Flashcards

Biology/Biochemistry Flashcards

1
Q

A solution of which of the following would generate the greatest osmotic pressure?

a. 0.2M AlCl3
b. 0.4M NaCl
c. 0.75M MgCl2
d. 1.0M Sucrose

A

c. 0.75M MgCl2

P = iMRT

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2
Q

In finches, the allele for brown feathers is dominant over the allele for white feathers. Two brown finches are crossed and produce offspring with 3:1 ratio of brown to white feathers. Assuming mendelian inheritance, what is the genotype of the parent finches?

a. BB and bb
b. BB and Bb
c. Bb and Bb
d. More than one of the above will produce a 3:1 ratio

A

c. Bb and Bb

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3
Q

Regions of DNA which appear to stain brightly under a microscope are most likely which of the following?

a. Heterochromatin
b. Centromeres
c. Euchromatin
d. Telomeres

A

c. Euchromatin

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4
Q

Which of the following enzymes reduces the supercoiling of DNA during replication?

a. Primase
b. Helicase
c. Gyrase
d. Ligase

A

c. Gyrase

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5
Q

When does the centromere of a chromosome get degraded?

a. Replication
b. Transcription
c. Translation
d. Mitosis

A

d. Mitosis (specifically, during anaphase)

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6
Q

If a eukaryotic cell has 28 homologous chromosomes, how many chromosomes will be present in a daughter cell by the end of mitosis?

A

28

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7
Q

If a eukaryotic cell has 28 homologous chromosomes, how many chromosomes will be present in a daughter cell by the end of meiosis?

A

14

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8
Q

Crossing over occurs during what phase of meiosis?

a. Metaphase 1
b. Anaphase 2
c. Prophase 1
d. Metaphase 2

A

c. Prophase 1

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9
Q

Crossing over takes place between which of the following?

a. Chromatids on both the same and different chromosomes
b. A chromatid and itself
c. Chromatids on separate chromosomes
d. Chromatids on the same chromosome

A

c. Chromatids on separate chromosomes

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10
Q

Which of the following is true regarding crossing over?

a. Two genes separated by a large number of map units cross over together more frequently
b. Linked genes are an example of Mendelian inheritance
c. Genes that are linked often crossover together
d. Crossing over is the only contributor to gamete genetic diversity during meiosis

A

c. Genes that are linked often crossover together

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11
Q

For a human cell, which of the following is true regarding anaphase 1 and 2?

a. During anaphase 1, homologous chromosomes separate; during anaphase 2, sister chromatids separate
b. During anaphase 1, sister chromatids separate; during anaphase 2, homologous separate
c. During both anaphase 1 and 2, homologous chromosomes separate
d. During both anaphase 1 and 2, sister chromatids separate

A

a. During anaphase 1, homologous chromosomes separate; during anaphase 2, sister chromosomes separate

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12
Q

Which of the following is true regarding polar bodies?

a. They receive an equal amount of genetic material
b. They receive an equal amount of organelles
c. They receive an equal amount of cytoplasm
d. None of the above

A

a. They receive an equal amount of genetic material

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13
Q

Which of the following is true regarding meiosis in human females?

a. During meiosis 1 only, a polar body is produced
b. During both meiosis 1 and 2, a polar body is produced
c. During meiosis 2 only, a polar body is produced
d. Polar bodies are produced in males, not females

A

b. During both meiosis 1 and 2, a polar body is produced

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14
Q

Considering a human cell undergoing meiosis, which of the following is NOT true?

a. Per cell, the number of chromosomes at the onset of meiosis 1 is 46
b. Per cell, the number of chromosomes at the onset of meiosis 2 is 23
c. Per cell, the number of chromosomes at the end of meiosis 1 is 46
d. Per cell, the number of chromosomes at the end of meiosis 2 is 23

A

c. Per cell, the number of chromosomes at the end of meiosis 1 is 46

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15
Q

Considering a human cell undergoing meiosis, which of the following is NOT true?

a. Per cell, the number of chromatids at the onset of meiosis 1 is 92
b. Per cell, the number of chromatids at the onset of meiosis 2 is 23
c. Per cell, the number of chromatids at the end of meiosis 1 is 46
d. Per cell, the number of chromatids at the end of meiosis 2 is 23

A

b. Per cell, the number of chromatids at the onset of meiosis 2 is 23

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16
Q

Which of the following is NOT part of the endomembrane system?

a. Nuclear envelope
b. Golgi apparatus
c. Ribosomes
d. Endoplasmic reticulum

A

c. Ribosomes

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17
Q

The endoplasmic reticulum is primarily responsible for

a. Beta-oxidation of fatty acid
b. Production of ATP
c. Synthesis of microtubules
d. Modification of proteins

A

d. Modification of proteins

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18
Q

Which of the following processes does NOT occur in peroxisomes?

a. Oxidation of amino acids
b. Neutralization of free radicals
c. Oxidation of glucose
d. Oxidation of fatty acids

A

c. Oxidation of glucose

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19
Q

Where are glycoproteins synthesized within a cell?

a. Smooth ER
b. Peroxisomes
c. Golgi apparatus
d. Rough ER

A

d. Rough ER

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20
Q

What is the primary component of the ER membrane?

a. Phospholipids
b. Triacylglycerols
c. Cholesterol
d. Lipoproteins

A

a. Phospholipids

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21
Q

Which component of the biological membrane is synthesized in the rough ER?

a. Integral proteins
b. Cholesterols
c. Ribosomal RNAs
d. DNA Polymerases

A

a. Integral proteins

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22
Q

The smooth ER is NOT responsible for which of the following?

a. Synthesis of steroid hormones
b. Synthesis of glycoproteins
c. Synthesis of lipids
d. Breakdown of toxins and drugs

A

b. Synthesis of glycoproteins

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23
Q

Which type of protein modification does NOT typically occur in the lumen of rough ER?

a. Phosphorylation
b. Glycosylation
c. Ubiquitination
d. Hydroxylation

A

c. Ubiquitination

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24
Q

Which organelle is specialized as a reservoir for Ca2+ in muscle tissue?

a. Golgi apparatus
b. Lysosome
c. ER
d. Centriole

A

c. ER

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25
Q

Decreased activity of which of the following is LEAST likely to decrease levels of cytosolic acetyl-CoA?

a. Pyruvate Dehydrogenase
b. Pyruvate carboxylase
c. Acyl-CoA synthetase short-chain family member 2
d. Citrate synthase

A

d. Citrate synthase

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26
Q

In addition to acetyl-CoA, which of the following is required for fatty acid synthesis?

a. NADPH
b. ADP
c. CoA-SH
d. FAD

A

a. NADPH

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27
Q

An increase in the activity of ACSS2 within hepatocytes is most likely to have which of the following effects?’

a. Decreased glycolytic flux
b. Increased Kreb’s cycle flux
c. Decreased pyruvate dehydrogenase flux
d. Increased lipid synthesis flux

A

d. Increased lipid synthesis flux

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28
Q

Monocytes, in conjunction with epithelium-derived factors, can act to facilitate which biological process?

a. Fatty acid oxidation
b. Transfection
c. Lipid synthesis
d. Host immune response

A

d. Host immune response

Monocytes are the largest type of white blood cells. Factors secreted by the epithelium help form a cascade that leads to accumulation of immune cells at the site of an injury

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29
Q

The symptoms of botulinum take 12-18 hours to be observed in a patient. How is this best explained?

a. Growing bacteria produce the toxin
b. Botulinum toxin is immediately filtered by the kidneys and excreted
c. Toxins can be absorbed through mucous membranes or respiratory tract
d. Most of the toxins are polar and they take time to cross the nuclear membrane

A

a. Growing bacteria produce the toxin

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30
Q

Which of the following will cause a blood pH of 8.2?

a. Decreased O2 concentration
b. Decreased tidal volume
c. Increased H2O concentration
d. Increased respiratory rate

A

d. Increased respiratory rate

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31
Q

Patients with excess fat are more likely to require larger therapeutic doses of which vitamin?

a. Vitamin B1
b. Vitamin C
c. Vitamin D
d. Vitamin B3

A

c. Vitamin D

Vitamins A, D, E, and K are lipid-soluble

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32
Q

Which of the following is most likely to use a protein channel to cross the eukaryotic cell membrane?

a. Aldosterone
b. Ca2+
c. O2
d. CO2

A

b. Ca2+

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33
Q

Which of the following is an element of humoral immunity?

a. Phagocytes
b. Immunoglobulins
c. T cells
d. MHC I

A

b. Immunoglobulins

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34
Q

A molecule enters a cell and creates pores in the inner mitochondrial membrane. Will oxidative phosphorylation continue to generate ATP?

a. Yes, because the cell membrane is still complete
b. Yes, because ATP is required for cell function
c. No, because there is no available oxygen
d. No, because the proton gradient will be dissipated

A

d. No, because the proton gradient will be dissipated

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35
Q

Which of the following receptors is specifically responsible for detecting changes in pressure?

a. Mechanoreceptors
b. Baroreceptors
c. Nociceptors
d. Chemoreceptors

A

b. Baroreceptors

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36
Q

Taste is an important sense that involves sensory receptors called:

a. nutriceptors.
b. chemoreceptors.
c. mechanoreceptors.
d. proprioceptors.

A

b. chemoreceptors

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37
Q

From the following, which receptors are not commonly found in humans?

a. Proprioceptors
b. Nociceptors
c. Osmoreceptors
d. Magnetoreceptors

A

d. Magnetoreceptors

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38
Q

What is the function of photoreceptors in the human body?

a. Photoreceptors detect stimuli that are then stored in long-term memory as a “photographic” representation
b. Photoreceptors detect visual stimuli in the form of infrared light
c. Photoreceptors detect wavelengths of light between 400 and 700 nanometers
d. Photoreceptors are not found in the human body

A

c. Photoreceptors detect wavelengths of light between 400 and 700 nanometers

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39
Q

Interoceptors include sensory receptors that:

a. detect information from internal environments
b. integrate information from multiple sensory receptors
c. produce information that is always perceived unconsciously
d. detect stimuli from the external environment such as sound waves

A

a. detect information from internal environments

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40
Q

Receptors in the ear belong to which of the following groups?

a. Electroreceptors
b. Mechanoreceptors
c. Photoreceptors
d. Interoceptors

A

b. Mechanoreceptors

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41
Q

Nociceptors, which detect harmful or noxious stimuli, belong to the group:

a. chemoreceptors
b. mechanoreceptors
c. both chemoreceptors and mechanoreceptors
d. neither chemoreceptors and mechanoreceptors

A

c. both chemoreceptors and mechanoreceptors

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42
Q

All of the following are considered mechanoreceptors, except:

a. olfactory receptors
b. nociceptors
c. baroreceptors
d. auditory receptors

A

a. olfactory receptors

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43
Q

Baroreceptors that detect pressure changes in the aortic arch are considered to be which of the following?

a. Interoceptors
b. Mechanoreceptors
c. Both A and B
d. Neither A or B

A

c. Both A and B

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44
Q

Pacinian corpuscles are receptors for pressure and vibration found in mammalian skin. The receptor itself contains many layers, much like an onion, and an action potential is generated when the layers become deformed. What kind of receptor is this?

a. Proprioceptor
b. Mechanoreceptor
c. Chemoreceptor
d. Electroreceptor

A

b. Mechanoreceptor

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45
Q

Protein Z is a dimer whose subunits are connected by disulfide bonds. Which of the following is true regarding the denaturation of Protein Z? (Note: BME is a reducing agent which breaks down disulfide bonds)

a. Heating Protein Z will reversibly breakdown its tertiary structure; adding BME will reversibly breakdown its quaternary structure
b. Heating Protein Z will reversibly breakdown its tertiary structure; adding BME will irreversibly breakdown its quaternary structure
c. Heating Protein Z will irreversibly breakdown its tertiary structure; adding BME will reversibly breakdown its quaternary structure
d. Heating Protein Z will irreversibly breakdown its tertiary structure; adding BME will irreversibly breakdown its quaternary structure

A

a. Heating Protein Z will reversibly breakdown its tertiary structure; adding BME will reversibly breakdown its quaternary structure

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46
Q

Which of the following enzyme types catalyzes the formation of a single bond between two substrates through the elimination of H2O?

a. Oxidoreductase
b. Ligase
c. Hydrolase
d. Isomerase

A

b. Ligase

47
Q

The induced fit model of enzyme binding states that which of the following molecules alters the enzyme active site to more closely match the shape of the substrate?

a. A coenzyme
b. The substrate
c. A cofactor
d. An allosteric effector

A

b. The substrate

48
Q

Which of the following enzymes is not required for DNA replication?

a. RNA primase
b. DNA polymerase
c. DNA ligase
d. DNA endonuclease

A

d. DNA Endonuclease

49
Q

DNA is read by the polymerase enzymes ______, and DNA is synthesized _____.

a. From the 5’ end to the 3’ end; from the 5’ end to the 3’ end.
b. From the 3’ end to the 5’ end; from the 3’ end to the 5’ end.
c. From the 5’ end to the 3’ end; from the 3’ end to the 5’ end.
d. From the 3’ end to the 5’ end; from the 5’ end to the 3’ end.

A

d. From the 3’ end to the 5’ end; from the 5’ end to the 3’ end.

50
Q

The role of which enzyme is to unwind DNA ahead of the replication fork?

a. DNA Topoisomerase
b. Single stranded binding protein
c. Unwinding enzyme
d. DNA Helicase

A

a. DNA Topoisomerase

51
Q

How can the M-M constant, Km, be derived from a Lineweaver-Burk plot (1/[S] vs. 1/V0)?

a. Km = (-1) * (x-intercept)
b. Km = (slope)
c. Km = (slope) * (1/y-intercept)
d. Km = 1 / (x-intercept)

A

c. Km = (slope) * (1/y-intercept)

52
Q

In a bacteria possessing the lac operon, which of the following occurs when glucose is low and lactose is abundant?

a. Transport of lactose into the cell is enhanced
b. Beta-galactosidase acetylases the operon
c. Lactose metabolism is increased by lactose binding to the operon
d. Lactose permease cleaves lactose to glucose and galactose

A

a. Transport of lactose into the cell is enhanced

53
Q

What is the role of an activator?

a. Enhances interaction between RNA polymerase and the promoter
b. Binds to an operon and transcribes RNA
c. Displaces a repressor protein from an operon, allowing RNA polymerase to proceed in transcription
d. Causes conformational changes in the DNA, bringing promoter regions into proximity with enhancer regions

A

a. Enhances interaction between RNA polymerase and the promoter

54
Q

Which of the following is true of large-scale deletions?

a. Usually involve changes to DNA as well as to epigenetic mechanisms
b. Enhance silencing of important oncogenes due to altered methylation
c. Less likely to be fatal than nucleotide-level mutations
d. More likely to result in frameshift mutations than small deletions

A

a. Usually involve changes to DNA as well as to epigenetic mechanisms

55
Q

Which of the following is NOT a way that transposons can affect the genome?

a. They can change the size of the genome
b. They can create new genes
c. They can delete old genes
d. They can result in genetic material being exchanged between two cells

A

d. They can result in genetic material being exchanged between two cells

56
Q

Which of the following processes involves bacteria taking in naked DNA from the extracellular environment?

a. Transposition
b. Conjugation
c. Transduction
d. Transformation

A

d. Transformation

57
Q

A cross between 2 pea plants with genotypes PpLl and PpLl results in an F1 generation that is 25% PPLL, 50% PpLl, and 25% ppll. Which reason most likely explains why other possible genotypes are not present?

a. The loci of the genes are on different chromosomes
b. Crossing over occurred between chromosomes
c. The genes underwent independent assortment
d. The loci of the genes are close together

A

d. The loci of the genes are close together

58
Q

If two genes experience independent assortment, which assumption is most likely true?

a. The expression of one gene does not affect the expression of the other
b. The genes are located on different chromosomes or are far apart on the same chromosome
c. Crossing over between the genes does not occur
d. They are located in close proximity on the same chromosome

A

b. The genes are located on different chromosomes or are far apart on the same chromosome

59
Q

In nature, restriction enzymes are meant to protect:

a. Bacteria from other bacteria
b. Humans from bacteria
c. Viruses from bacteria
d. Bacteria from viruses

A

d. Bacteria from viruses

60
Q

A student was attempting to make cDNA that would code for protein Y. They began with an isolated and amplified sample of the target post-transcriptional mRNA, and all the tools required to complete the task. However, at the end of the experiment the student was left with a molecule containing ribonucleotides. What most likely went wrong?

a. The cloning vector already transcribed the DNA
b. The student added RNA polymerase instead of DNA polymerase
c. The student forgot to add reverse transcriptase
d. The student forgot to add DNA polymerase

A

c. The student forgot to add reverse transcriptase

61
Q

Which of the following population’s coat/fur/feather colour gene is most likely to be in Hardy-Weinberg equilibrium?

a. A pack of wolves in the zoo
b. A flock of moths that must blend in with their environment to survive
c. Lab rats being bred by scientists
d. A flock of seagulls that feeds on one type of fish

A

d. A flock of seagulls that feeds on one type of fish

Mating must be random and no natural selection is occurring

62
Q

A gene, TALL, has recently been discovered that helps control the height that people will reach and results in taller than average height. Which of the following statements about this gene’s heritability are true?

a. If TALL has 50% penetrance, then only half of the population has the TALL gene
b. If TALL has 25% penetrance, it must be autosomal recessive
c. If TALL has constant expressivity, then every cell in the body will express the TALL protein
d. If TALL has variable expressivity, everyone with the TALL gene will be tall

A

d. If TALL has variable expressivity, everyone with the TALL gene will be tall (100% penetrance)

63
Q

Most people have DNA mutations that go unnoticed. What type of mutation is most likely to have no effect on phenotype?

a. Deletion
b. Chromosomal
c. Frameshift
d. Missense

A

d. Missense

64
Q

Sickle-cell anemia is an autosomal recessive genetic disorder whose carriers have a genetic advantage in surviving malaria. If 42% of the population is malaria resistant, but not anemic, what is the frequency of the sickle-cell allele?

a. 30%
b. 49%
c. 21%
d. 9%

A

a. 30%

2pq = 0.42
pq = 0.21
p + q = 1
p = 0.30
q = 0.70
65
Q

Which of the following experimental methods is NOT used to determine gene expression?

a. Western blotting
b. Reverse transcription PCR
c. Northern Blotting
d. PCR

A

d. PCR

66
Q

Glucose and galactose are:

a. anomeric at the C2 position
b. epimeric at the C2 position
c. anomeric at the C4 position
d. epimeric at the C4 position

A

d. Epimeric at the C4 position

67
Q

The production of interferon most likely signals an infection by what type of pathogen?

a. An extracellular virus
b. An intracellular virus
c. An extracellular bacteria
d. An extracellular bacteria

A

b. An intracellular virus

68
Q

Which of the following scenarios represents disruptive selection within a population?

a. Heterozygous pink flowers are selected against while homozygous red and homozygous white flowers are selected for
b. Oak trees with medium-sized leaves are evolutionarily favoured, as large leaves suffer from dehydration and small leaves don’t receive sufficient sun
c. A population of snakes is split by the construction of a large road, causing speciation of the divided populations
d. As pollution creates turbidity in a lake, brighter fish have greater reproductive success, causing the population to become more brightly coloured on average

A

a. Heterozygous pink flowers are selected against while homozygous red and homozygous white flowers are selected for

Disruptive selection occurs when two extreme phenotypes on a continuum are selected for

69
Q

Researchers are seeking evidence to confirm a close evolutionary relationship between two extant species. Which of the following pieces of evidence would be LEAST likely to help the researchers demonstrate this relationship?

a. A fossil that shares traits with both species
b. The sequence of a ribosome-coding gene from each species
c. The discovery of similar stages of embryonic development
d. The identification of several analogous structures between the species

A

d. The identification of several analogous structures between the species

Analogous structures serve the same function, but come from a different evolutionary origin

70
Q

Which term describes alterations in the composition of a gene pool due to migration of individuals between different populations?

a. Assortive mating
b. Genetic drift
c. Directional selection
d. Gene flow

A

d. Gene flow

71
Q

As prehistoric humans moved to different regions of the globe, different populations began expressing different concentrations of melanin in their skin. This is an example of which evolutionary concept?

a. Genetic drift
b. Parallel evolution
c. Adaptive radiation
d. Convergent evolution

A

c. Adaptive radiation

72
Q

Aerobic cellular respiration involves the flow of electrons from one chemical species to another: which of the following best describes this process?

a. Electrons are transferred from oxygen to glucose
b. Electrons are transferred from glucose to carbon dioxide
c. Electrons are transferred from oxygen to water
d. Electrons are transferred from glucose to oxygen

A

d. Electrons are transferred from glucose to oxygen

73
Q

Under which of the following conditions would one expect ATP hydrolysis to be non-spontaneous?

a. A temperature slightly below 37 C
b. No enzymes available to lower activation energy
c. A very basic environment
d. ATP concentrations very far below equilibrium, and ADP concentrations very far above equilibrium

A

d. ATP concentrations very far below equilibrium, and ADP concentrations very far above equilibrium

74
Q

Given that NAD, in its reduced form as NADH, is a key electron-donating molecule in many metabolic reactions, which of the following is a good prediction for the standard reduction potential (E) of the reduction half-reaction of NAD?

a. Large and positive
b. Less than zero
c. Zero
d. Between zero and 1

A

b. Less than zero

75
Q

Glucose is oxidized to what molecule during aerobic cellular respiration?

a. Water
b. Carbon dioxide
c. Oxygen
d. ATP

A

b. Carbon dioxide

76
Q

Which of the following molecules is NOT a product of the citric acid cycle?

a. Carbon dioxide
b. NADH
c. FADH2
d. Pyruvate

A

d. Pyruvate

77
Q

Which of the following is least essential for ATP synthesis via oxidative phosphorylation?

a. H+
b. Glucose
c. Cytochrome c
d. Ubiquinone

A

b. Glucose

78
Q

Which enzyme is used in the Krebs cycle?

a. Fumarase
b. Hexokinase
c. Pyruvate kinase
d. Pyruvate dehydrogenase

A

a. Fumarase

79
Q

Which enzyme of the Krebs cycle participates in the formation of NADH and carbon dioxide?

a. Fumarase
b. Aconitase
c. Succinic dehydrogenase
d. Isocitrate dehydrogenase

A

d. Isocitrate dehydrogenase

80
Q

Which intermediate is not generated by the Krebs cycle?

a. Citrate
b. Succinate
c. Pyruvate
d. Malate

A

c. Pyruvate

81
Q

Which molecules are consumed and produced by the Krebs cycle?

a. NADH
b. H2O
c. CO2
d. GTP

A

b. H2O

82
Q

Which is not a substrate used in the Krebs cycle?

a. 3-carbon molecules
b. 4-carbon molecules
c. 5-carbon molecules
d. 6-carbon molecules

A

a. 3-carbon molecules

83
Q

Which molecule stimulates the Krebs cycle?

a. ATP
b. ADP
c. NADH
d. Succinyl-CoA

A

b. ADP

84
Q

Which Krebs cycle enzyme does not participate in the formation of NADH?

a. Malate dehydrogenase
b. a-ketoglutarate dehydrogenase
c. Isocitrate dehydrogenase
d. Succinate dehydrogenase

A

d. Succinate dehydrogenase

85
Q

Which of the following molecules is the aldose form of fructose?

a. Sucrose
b. Lactose
c. Glucose
d. Galactose

A

c. Glucose

Aldose is a monosaccharide molecule with one aldehyde functional group

86
Q

Which of the following carbohydrates does not contain at least one glycosidic linkage?

a. Sucrose
b. Amylose
c. Lactose
d. Mannose

A

d. Mannose

87
Q

Which of the following describes the relationship between the straight chain forms of D-glucose and D-galactose, given that they are non-cyclic molecules that differ only in stereochemical configuration at the fourth carbon?

a. They are meso-compounds
b. They are enantiomers
c. They are epimers
d. They are anomers

A

c. They are epimers

88
Q

Which of the following is usually found within prokaryotes but not in eukaryotes?

a. A nuclear membrane
b. Transcription factors
c. Monocistronic genes
d. Operons

A

d. Operons

89
Q

Which of the following describes a polycistronic vs. monocistronic gene?

a. Monocistronic genes feature multiple genes controlled by a single promoter
b. Monocistronic genes feature single genes controlled by multiple promoters
c. Polycistronic genes feature multiple genes controlled by a single promoter
d. Polycistronic genes feature multiple genes controlled by multiple promoters

A

c. Polycistronic genes feature multiple genes controlled by a single promoter

90
Q

Which of the following correctly compares eukaryote and prokaryotes?

a. Prokaryote mature RNA retains its introns
b. Eukaryotic mature RNA retains its introns
c. Eukaryotic mature RNA contains exons and introns
d. Prokaryotic RNA has no introns

A

d. Prokaryotic RNA has no introns

91
Q

Which of the following correctly compares eukaryote and prokaryote gene transcription?

a. Gene transcription and protein translation can occur simultaneously in prokaryotes, but not in eukaryotes
b. Polysomes (multiple ribosomes attached to RNA) occur in prokaryotes, but not eukaryotes
c. Gene transcription and post-transcriptional processing can occur simultaneously in eukaryotes, but not prokaryotes
d. All of the above are true

A

a. Gene transcription and protein translation can occur simultaneously in prokaryotes, but not in eukaryotes

92
Q

In the context of gene transcription, which of the following is true?

a. cis-elements include transcription factors
b. cis-elements are coding DNA sequences to which trans elements bind
c. trans elements are free molecules that can diffuse through the cytoplasm
d. trans elements are always protein based

A

c. trans elements are free molecules that can diffuse through the cytoplasm

93
Q

Considering a prokaryotic operon, which of the following is true regarding activators?

a. An activator is a cis DNA sequence which binds to a repressor trans element
b. An activator is a trans-element which binds to a repressor trans element
c. An activator is a cis DNA sequence which binds to an inducer trans element
d. An activator is a trans-element which binds to an operator cis DNA sequence

A

d. An activator is a trans-element which binds to an operator cis DNA sequence

94
Q

In the prokaryotic Lac Operon, allolactose binds to and inhibits the repressor. Which of the following terms applies to allolactose?

a. Operator
b. Inducer
c. Activator
d. Silencer

A

b. Inducer

95
Q

Which of the following would most likely result in the separation of a dimer into its constituent monomers?

a. Reduction of a disulfide bond
b. Oxidation of a disulfide bond
c. Hydrolysis of an amide linkage
d. Condensation of an amide linkage

A

a. Reduction of a disulfide bond

96
Q

Which of the following promotes the binding of a myosin head to a thin filament?

a. Closing of voltage gated sodium ion channels
b. A conformational change in tropomyosin
c. Active transport of calcium ions into the sarcoplasmic reticulum
d. Myosin heads binding to ATP

A

b. A conformational change in tropomyosin

97
Q

At physiological pH, what is the net charge on the peptide chain RDSML?

a. -1
b. 0
c. +1
d. +2

A

b. 0

98
Q

With respect to their relative pH, how do the cytosol, intermembrane space of the mitochondria, and the mitochondrial matrix compare?

a. pH of mitochondrial matrix > pH of cytosol > pH of intermembrane space
b. pH of cytosol > pH of intermembrane space = pH of mitochondrial matrix
c. pH of intermembrane space < pH of mitochondrial matrix < pH of cytosol
d. pH of mitochondrial matrix < pH of cytosol = pH of intermembrane space

A

a. pH of mitochondrial matrix > pH of cytosol > pH of intermembrane space

99
Q

High cellular concentrations of what molecule would inhibit the entry of pyruvate into the citric acid cycle?

a. Coenzyme A
b. Pyruvate
c. AMP
d. NADH

A

d. NADH

100
Q

From where does the reactive oxygen species known as the superoxide anion (O2-) originate?

a. As a naturally occurring byproduct of multiple body processes
b. Exogenous (outside the body) sources only
c. As a product of superoxide dismutase
d. As a malfunction of the electron transport chain and oxidative phosphorylation

A

a. As a naturally occurring byproduct of multiple body processes

101
Q

How many molecules of oxygen (O2) are required to complete the reactions of aerobic respiration beginning with four molecules of glucose?

a. 24
b. 4
c. 16
d. 6

A

a. 24

102
Q

What is the approximate total yield of ATP that is produced via the Krebs cycle and subsequent oxidative phosphorylation of a single molecule of acetyl CoA?

a. 16
b. 20
c. 32
d. 10

A

d. 10

103
Q

What would occur if all available hydrogen ions were used by ATP synthase?

a. It would increase the levels of inorganic phosphate in the mitochondrial matrix
b. It would increase the pH of the mitochondrial matrix
c. It would increase the pH of the mitochondrial intermembrane space
d. It would decrease the levels of inorganic phosphate in the intermembrane space

A

c. It would increase the pH of the mitochondrial intermembrane space

H+ is taken from the intermembrane space, increasing pH

104
Q

Predict the outcome of a mitochondrial membrane that is more permeable to hydrogen ions than normal.

a. Reduced formation of water
b. Reduced activity of ETC
c. Increased activity of ATP synthase
d. Increased levels of inorganic phosphate in the mitochondrial matrix

A

d. Increased levels of inorganic phosphate in the mitochondrial matrix

105
Q

Which complex of the ETC in cellular respiration does not directly impact the intermembrane space’s pH?

a. Complex II
b. Complex IV
c. Complex III
d. Complex I

A

a. Complex II

106
Q

Cyanide is a poison that inhibits the ETC by creating a strong and stable bond with Fe-Cu center in cytochrome C oxidase (Complex IV). What is the immediate consequence of cyanide poisoning?

a. Prevents reduction of oxygen
b. Prevents oxidation of oxygen
c. Prevents reduction of NADH
d. Prevents oxidation of NADH

A

a. Prevents reduction of oxygen

107
Q

Sphingolipids are composed of which of the following?

a. A sphingosine backbone, three free fatty acids
b. A sphingosine backbone, a fatty acid, and a unique functional group
c. A sphingosine backbone, a phosphate group, and 1 or 2 fatty acids
d. A sphingosine backbone, a phosphate group, and a unique functional group

A

b. A sphingosine backbone, a fatty acid, and a unique functional group

108
Q

Which of the following is true regarding steroids?

a. They are composed of 1 six-membered ring and 2 five-membered rings
b. They are composed of 2 six-membered rings and 2 five-membered rings
c. They are composed of 1 six-membered ring and 3 five-membered rings
d. They are composed of 3 six-membered rings and 1 five-membered ring

A

d. They are composed of 3 six-membered rings and 1 five-membered ring

109
Q

Triterpenes have what molecular formula?

a. C30H48
b. C15H24
d. C5H8
d. C10H16

A

a. C30H48

110
Q

The simplest class of sphingolipid is the:

a. Ganglioside
b. Cerebroside
c. Ceramide
d. Globoside

A

c. Ceramide

111
Q

Which of the following hormones always requires an extracellular receptor?

a. T4
b. Glucagon
c. Cortisol
d. Aldosterone

A

b. Glucagon

(Peptide hormone)

112
Q

Which cell type is involved in the cell-mediated immune response?

a. Mast cells
b. T lymphocytes
c. Macrophages
d. B cells

A

b. T lymphocytes

113
Q

Which cell type can display MHC II on their surface?

a. Hepatocytes
b. Goblet cells
c. Dendritic cells
d. Cytotoxic T cells

A

c. Dendritic cells

114
Q

Which of the following is not a resident macrophage?

a. Microglia
b. Monocyte
c. Osteoclast
d. Langerhans cell

A

b. Monocyte

MCAT! (10 decks)

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