Missed B/B questions

Question 1

What is the total number of fused rings in a Steroid?

Answer 1

4

Question 2

Epilepsy may result in motor seizures due to massive synchronous firing of neurons in a small area of the cerebral cortex (the epileptic focus). Excitation spreads from the focus, involving an increasingly larger area of the cortex. A drug for the treatment of epilepsy would be most effective if it caused which of the following changes in the epileptic focus?

A.

An increase in the neuron-firing threshold

B.

An increase in extracellular Na+ concentration

C.

A decrease in axon–membrane permeability to negative ions

D.

A decrease in the length of the depolarization stage

Answer 2

A

A drug that would best treat epilepsy, as described, should reduce the activity of the neurons in the epileptic focus, which are excitatory neurons based on their effect throughout the cortex. The answer to this question is A because increasing the threshold required to generate an action potential would decrease the chance that individual neurons would fire, thus reducing the overall amount of excitation that spreads from the epileptic focus throughout the cortex.

Question 3

When concentrated urine is being produced, in which of the following regions of the kidney will the glomerular filtrate reach its highest concentration?

A.

Proximal convoluted tubule

B.

Distal convoluted tubule

C.

Cortical portion of the collecting duct

D.

Medullary portion of the collecting duct

Answer 3

The answer is D because glomerular filtrate is most concentrated in the medullary portion of the collecting duct, compared to the other kidney structures listed.

Question 4

What is the function of transcription factors?

Answer 4

They may bind directly to special “promoter” regions of DNA, which lie upstream of the coding region in a gene, or directly to the RNA polymerase molecule. They recruit RNA polymerase

Question 5

What do ABC transporters do?

Answer 5

ABC transporters utilize the energy of ATP binding and hydrolysis to transport various substrates across cellular membranes.

Question 6

What is a lipid raft?

Answer 6

Lipid rafts are defined as cholesterol- and sphingolipid-enriched membrane domains and numerous studies have attempted the lipid characterization of caveolae and raft domains.

Question 7

What is an oligosaccharide?

Answer 7

a carbohydrate whose molecules are composed of a relatively small number of monosaccharide units.

Question 8

The initial filtration step in the glomerulus of the mammalian kidney occurs primarily by:

A.

passive flow due to a pressure difference.

B.

passive flow resulting from a countercurrent exchange system.

C.

active transport of water, followed by movement of electrolytes along a resulting concentration gradient.

D.

active transport of electrolytes, followed by passive flow of water along the resulting osmolarity gradient.

Answer 8

The answer to this question is A because the initial filtration in the glomerulus occurs as blood pressure forces the fluid from the glomerulus into the lumen of Bowman’s capsule.

Question 9

Enzymes alter the rate of chemical reactions by all of the following methods EXCEPT:

A.

co-localizing substrates.

B.

altering local pH.

C.

altering substrate shape.

D.

altering substrate primary structure.

Answer 9

The answer to this question is D. The primary structure of a protein substrate is the amino acid sequence of the protein. Enzymes cannot alter primary structures of protein, but can colocalize substrates, alter local pH, and alter substrate shape.

Question 10

The statement that the ornithine decarboxylase assay is highly specific means that it:

A.

requires radioactive ornithine of high specific activity.

B.

generates diaminobutane of high specific activity.

C.

an distinguish ornithine decarboxylase activity from the many other enzymatic reactions in a cell.

D.

can measure the small amount of ornithine present in a cell.

Answer 10

The answer to this question is C because enzymes such as ornithine decarboxylase are highly specific both in the reactions that they catalyze and in their choice of substrates and therefore catalyze only a single chemical reaction or occasionally a set of closely related reactions.

Question 11

The lung cells of heavy smokers would be expected to have greatly increased concentrations of cP-450 and:

A.

DNA sequences that code for cP-450.

B.

mRNA sequences that code for cP-450.

C.

rRNA that process cP-450.

D.

tRNA that are specific for cysteine.

Answer 11

The answer to this question is B, because protein levels relate most directly to mRNA levels.

Question 12

The role of cP-450 in the metabolism of toxins may be exemplified by the following case in which a chronic alcoholic died of a barbiturate overdose.

While sober, the alcoholic was having trouble falling asleep and, therefore, took the recommended dosage of sleeping pills (barbiturates). When no drowsiness was felt, the alcoholic consumed more sleeping pills, then drank an alcoholic beverage. Severe respiratory depression and death soon followed caused by an overdose of barbiturates. An autopsy revealed that if alcohol had not been present, the barbiturates would have been metabolized rapidly enough to be eliminated by the body, and death would not have occurred.

No drowsiness was initially felt by the alcoholic because the previous abuse of alcohol had:

A.

denatured the cP-450.

B.

inhibited the cP-450.

C.

reduced the cP-450.

D.

induced the cP-450.

Answer 12

The answer to this question is D, because the passage states that cP-450 is inducible and thus previous abuse of alcohol, a cellular toxin, results in an increased concentration of cP-450. This leads to rapid barbiturate metabolism by cP-450 and the absence of initial drowsiness.

Question 13

What happens during interphase?

Answer 13

Interphase is the phase of the cell cycle between cell divisions and is the phase in which the cell obtains nutrients, grows, reads its DNA, and conducts other “normal” cell functions.

Question 14

Do mammilian erythrocytes contain DNA?

Answer 14

No. Erythrocytes lose their nuclei during maturation

Question 15

Which of the following best describes the bond that would form between the following two nucleotides if they were located adjacent to each other as shown in a single strand of DNA?

A.

A bond between the phosphate of the thymine and the phosphate of the adenine

B.

A bond between an oxygen in the thymine base and a nitrogen in the adenine base

C.

A bond between the phosphate of the thymine and the sugar of the adenine

D.

A bond between the phosphate of the adenine and the sugar of the thymine

Answer 15

The answer to this question is D because nucleotides are linked to one another by phosphodiester bonds between the sugar base of one nucleotide and the phosphate group of the adjacent nucleotide in a way that the 5’ end bears a phosphate, and the 3’ end a hydroxyl group.

Question 16

ACTH function

Answer 16

Adrenocorticotropic hormone (ACTH) is made in the pituitary gland. … ACTH stimulates the release of another hormone called cortisol from the cortex (outer part) of the adrenal gland. … Secretion of ACTHis controlled by three regions of the body, the hypothalamus, the pituitary gland ..

Question 17

the uptake of glucose. However, insulin does stimulate the first step in the glycolytic pathway within the liver. Therefore, in liver cells, insulin most likely:

A.

hinders glucose uptake by increasing the cellular concentration of glucose.

B.

aids glucose uptake by decreasing the cellular concentration of glucose.

C.

hinders glucose uptake by using the ATP needed by the glucose transporter proteins.

D.

aids glucose uptake by providing the ATP needed by the glucose transporter proteins.

Answer 17

The answer to this question is B because the stem states that insulin stimulates the first step in the glycolytic pathway in the liver, thus decreasing the cellular concentration of glucose. This results in increased uptake of glucose to maintain the cellular concentration of glucose.

Question 18

During the production of insulin, the translated polypeptide is cleaved into the mature form and secreted from the cell. The cleavage most likely takes place in which of the following locations?

A.

Nucleus

B.

Ribosomes

C.

Endomembrane system

D.

Cytoplasm

Answer 18

The answer to this question is C because secreted proteins such as insulin are cleaved into mature form within endomembrane system.

Question 19

A certain bacterium was cultured for several generations in medium containing 15N, transferred to medium containing 14N, and allowed to complete two rounds of cell division. Given that the bacterium’s genome mass is 5.4 fg when grown in 14N media and 5.5 fg when grown in 15N medium, individual bacteria with which of the following genome masses would most likely be isolated from this culture?

A.

5.4 fg only

B.

5.4 fg and 5.45 fg

C.

5.4 fg and 5.5 fg

D.

5.45 fg only

Answer 19

The answer to this question is B because DNA replication is semi-conservative. Therefore, after the first round of cell division the genome mass in each bacterium will be 5.45 fg (one DNA strand will contain 15N and the other strand 14N). Following the second round of cell division, half of the bacteria will have a genome mass of 5.4 fg (14N exclusively) and the other half a mass genome of 5.45 fg (14N in one DNA strand and 15N in the other).

Question 20

A stable, differentiated cell that will NOT divide again during its lifetime would most likely be found in which of the following stages of the cell cycle?

A. G1

B. G2

C. M

D. S

Answer 20

The correct answer is A.

The question asks the examinee to identify the cell cycle stage in which a stable, differentiated, nondividing cell will most likely be found. A diploid, nondividing cell is most likely in G0 or G1, in which the cell remains metabolically active but is not replicating its DNA (S) or segregating its duplicated chromosomes and dividing (M). A is the only option that lists either G0 or G1. Thus, A is the best answer.

Question 21

Most viral proteins are produced directly by:

A. translation of host nucleic acid.

B. translation of viral nucleic acid.

C. transcription of host nucleic acid.

D. transcription of viral nucleic acid.

Answer 21

The correct answer is B.

Transcription is copying; translation is changing the language. In cellular metabolism transcription refers to taking DNA and making an RNA copy; translation refers to taking the RNA, a series of nucleotides, and putting it into protein language, a series of amino acids. Some viruses have a genome consisting of RNA and this can be directly translated by the ribosome. Others use DNA as the genetic material and require transcription as well. Both, however, ultimately make proteins by translating their specific RNAs into protein, so the answer is B.

Question 22

If the DNA of a representative species from each of the major kingdoms was examined, the sequences coding for which of following would be expected to be most similar?

A. Photosynthesis

B. Cholesterol synthesis

C. Protein modification

D. DNA synthesis

Answer 22

D is correct. DNA sequences that are common among different species, phyla, or even kingdoms are called conserved sequences. Conserved sequences tend to remain that way due to the fact that they code for a vital function that is common among disparate species.

Question 23

Which of the following is an accurate statement regarding mitosis and meiosis?

A. Mitosis results in two haploid daughter cells.

B. During mitosis and meiosis II, sister chromatids are separated.

C. During meiosis I and meiosis II, sister chromatids are separated.

D. Meiosis I results in two diploid daughter cells.

Answer 23

B is correct. This question is asking us to recall some facts about mitosis and meiosis. Remember that mitosis separates sister chromatids to create two diploid daughter cells. Meiosis I separates homologous chromosomes to create haploid daughter cells, each of which divides again, separating sister chromatids in Meiosis II to create two haploid cells.

Question 24

Do bacteria contain introns?

Answer 24

For the most part, bacteria lack introns, whereas large eukaryotic genes usually contain several introns. A large, eukaryotic gene without introns suggests a bacterial origin.

Question 25

Which of the following changes occur immediately following the consumption of a carbohydrate-rich meal? A. Insulin secretion decreases; G6PD activity increases. B. Insulin secretion decreases; G6PD activity decreases. C. Insulin secretion increases; G6PD activity increases. D. Insulin secretion increases; G6PD activity decreases.

Answer 25

C is correct. From outside knowledge, we know that insulin secretion increases after a meal to help the cells take up glucose from the bloodstream. The passage states that the PPP is a parallel (alternative) path to glycolysis, so it makes sense that it would also be activated when blood sugar levels rise after a meal.

Question 26

In severe diabetic hyperglycemia (high blood sugar), insulin cannot effectively induce the uptake of glucose by cells. Chronic hyperglycemia directly leads to the presence of which of these molecules in the urine? I. Proteins II. Glucose III. Ketone bodies

Answer 26

Glucose and Ketone Bodies C is correct. This question requires outside knowledge about glucose metabolism. If cells cannot take up glucose, it will remain in the blood and eventually be excreted in the urine when it builds up to the point that it cannot be reabsorbed by the nephron. In a state of extended hyperglycemia, the body relies on fat metabolism to generate energy, which produces ketone bodies that are also excreted in the urine. Therefore, Roman numerals II and III are correct.

Question 27

Meiosis I results in: A. 2 diploid cells with 46 chromosomes, each chromosome consisting of 2 sister chromatids. B. 2 haploid cells with 46 chromosomes, each chromosome consisting of 1 chromatid. C. 2 haploid cells with 23 chromosomes, each chromosome consisting of 2 sister chromatids. D. 2 diploid cells with 23 chromosomes, each chromosome consisting of 1 chromatid.

Answer 27

C is correct. Meiosis I results in 2 haploid cells, each with 23 chromosomes consisting of 2 sister chromatids per chromosome. In the male, the sister chromatids are split into 4 gametes during meiosis II. For females, meiosis I results in a secondary oocyte (a gamete) and a polar body. Penetration of the secondary oocyte by a sperm brings on anaphase II. Telophase II produces a zygote and a second polar body. Remember for the MCAT: mitosis results in diploid daughter cells, while meiosis results in haploid cells to produce gametes.

Question 28

The concentration of intracellular signaling molecules fluctuates rapidly in dividing cells during the cell cycle. Which of the following experimental techniques would be best to elucidate the mechanism of regulation for these proteins? A. RT-PCR and Southern blot B. Southern blot and northern blot C. Western blot and RT-PCR D. Western blot and Southern blot

Answer 28

C is correct. Rapidly dividing cells undergo mitosis under the influence of specific signaling molecules. These molecules are expressed when their genes are transcribed, then are translated into proteins. In order to gain the best understanding of how a signaling protein’s levels are regulated, both the protein and mRNA levels would need to be studied. Western blotting gives us information about the amount of protein expressed in a cell, while RT-PCR gives us information about the amount of RNA expressed

Question 29

What is a nucleoside?

Answer 29

A nucleoside is composed of a nitrogenous base and a five-carbon sugar (ribose or deoxyribose). Adenosine, shown below, is such a molecule

Question 30

Folate is a common supplement given to pregnant women to prevent neural tube defects. The most likely reason for this is: A. folate is involved in action potential transmission from mother to fetus. B. folate is directly involved in erythropoiesis. C. folate is critical for proper development of the mesoderm. D. folate plays a role in ectodermal induction.

Answer 30

D is correct. Neural tube defects are defects in the central nervous system. The nervous system is derived from the ectoderm. It can be concluded from the given information that folate is important for neurulation, or the induction of the ectoderm to differentiate into the nervous system.

Question 31

In human females, mitotic divisions of oogonia that lead to formation of presumptive egg cells (primary oocytes) occur between: A fertilization and birth only. B fertilization and puberty only. C birth and puberty only. D puberty and menopause only.

Answer 31

The correct answer is A. The question asks the examinee to identify the stages in the human female life cycle between which all the mitotic divisions that lead to primary oocyctes occur. These stages occur in the following order: fertilization, birth, puberty, menopause. All of the mitotic divisions that form primary oocytes occur prior to birth

Question 32

An alternative method for examining the effects of fatty acids on blood flow would be to measure changes in blood pressure. If blood pressure were measured, one would predict that it would be lowest in which of the following? A Heart B Arteries C Arterioles D Capillaries

Answer 32

The correct answer is D. ## Footnote An alternative method for examining the effects of fatty acids on blood flow would be to measure changes in blood pressure. It blood pressure were measured, one would predict that blood pressure would be lowest in the capillaries, as compared to the heart, arteries, or arterioles. Pressure would be even lower in the veins, but this option was not offered.

Question 33

What is the primary function of the colon?

Answer 33

Its function is to reabsorb fluids and process waste products from the body and prepare for its elimination

Question 34

Normally the immune system avoids attacking the tissues of its own body because: A a special intracellular process recognizes only foreign antigens. B the body does not make any antigens that the immune system could recognize. C it changes its antibodies to be specific only to foreign antigens. D it suppresses cells specific to the body's own antigens.

Answer 34

Solution: The correct answer is D. The immune system is designed to attack foreign material in the body. It avoids attacking tissues of its own body because it suppresses cells that are specific to its own body’s antigens (surface molecules that would otherwise initiate an immune response).

Question 35

An ulcer that penetrated the wall of the intestine would allow the contents of the gastrointestinal tract to enter: A the perineum. B the peritoneal cavity. C the pleural cavity. D the lumen of the intestine.

Answer 35

Solution: The correct answer is B. If an ulcer penetrated the walls of the intestine, this would allow the contents of the gastrointestinal tract to enter the peritoneal cavity. Membranes surround this cavity, which would prevent further transport of the gastrointestinal contents through the rest of the body. An ulcer in the small intestine would not allow the contents to enter the lumen because this is the normal place in which the contents are found.

Question 36

In the ETC, Electrons are passed from carriers with _____ reduction potential to those with _____ reduction potential.

Answer 36

lower, higher

Question 37

Which of the following is NOT considered an organic acid? A. Folic acid B. Carbonic acid C. Ascorbic acid D. Citric acid

Answer 37

B is correct. An organic compound must contain carbon and hydrogen in its formula. Furthermore, there must be a covalent bond between a carbon and hydrogen atom in the molecular structure. Organic acids are weak acids, generally having formulas of R-CO2H, with the acidic hydrogen bonded to an oxygen atom. Even knowing this information, you may be intimidated, as you may not be familiar with the structures of all of these choices. However, you can begin with the most familiar compound, carbonic acid. The Lewis structure of this compound is shown below.

Question 38

Conn's syndrome, also known as primary hyperaldosteronism, is most likely to cause which symptom? A. High renin concentration B. Low blood potassium C. Low blood sodium D. Hypotension

Answer 38

B is correct. This question is asking you to recall the effects of aldosterone and how it achieves those effects. Aldosterone increases H2O and Na+ reabsorption from the kidney while exchanging K+ ions for Na+ ions

Question 39

Viruses are directly involved in which of the following processes in bacteria? A. Transformation B. Conjugation C. Transduction D. Binary fission

Answer 39

C is correct. Transduction is a form of horizontal gene transfer in bacteria in which bacteriophages (viruses that infect bacteria) transmit genomic material.

Question 40

In an adult, which of the following cell types is LEAST likely to enter a programmed G0 phase of the cell cycle? A. Liver cells B. Kidney cells C. Epithelial cells D. Neurons

Answer 40

C is correct. For this question, we need to know what the G0 phase (shown below along with the rest of the cell cycle) entails. This is the state that a cell will enter if it does not need to divide. Since epithelial cells are those that divide the most out of the options, choice C is correct.

Question 41

What are the purines? What makes them special?

Answer 41

Purines have a 2 rings structure. They are Guanine and Adenine

Question 42

What are the pyrimidines?

Answer 42

They only have 1 ring in their structure. They are Cytosine, Uracil, and Thymine (Remember CUT)

Question 43

NADPH to NADP+ is what?

Answer 43

NADPH is oxidized to NADP+

Question 44

The SN2 mechanism is favored by ______ solvents,

Answer 44

polar aprotic

Question 45

What is the function of ligase during S-phase? A. Begins synthesis of a new strand of copied DNA B. Binds together pieces of the lagging strand C. Repairs pieces of mis-replicated DNA D. Opens the double helical strand of DNA to begin replication

Answer 45

B is correct. This question is asking us to simply recall a fact about the S-phase of a cell, aka DNA replication. You should know that DNA ligase is the enzyme that connects Okazaki fragments on the lagging strand of DNA being replicated. An overview of some of the key structures and enzymes of DNA replication is shown below.

Question 46

Which of the following would be LEAST useful in cellular movement? A. Flagella B. Actin polymerization C. Microtubule depolymerization D. Cilia

Answer 46

C is correct. In order for cells to travel to the site of injury, they need to migrate. Microtubule de-polymerization is responsible for separating chromosomes during anaphase of mitosis or meiosis I or II. It does not contribute to overall cell migration.

Question 47

Difference between nucleotide and nucleoside?

Answer 47

Nucleoside vs. Nucleotide. A nucleoside consists of a nitrogenous base covalently attached to a sugar (ribose or deoxyribose) but without the phosphate group. A nucleotide consists of a nitrogenous base, a sugar (ribose or deoxyribose) and one to three phosphate groups.

Question 48

Phosphotase

Answer 48

class of hydrolase responsible for the cleavage of phosphate bonds utilizing water to remove a molecule of inorganic phosphate

Question 49

Kinase

Answer 49

an enzyme that catalyzes the transfer of a phosphate group from ATP to a specified molecule.

Question 50

How many electrons does cytochrome C carry?

Answer 50

1 electron

Question 51

Which primer is most suitable for PCR? A. 5–ATTACGTTAACATGAAG–3 B. 5–ATATCGTTAACAAATTG–3 C. 5–GCTATAAAGATTGCAAA–3 D. 5–GCATAGAAGCATTCCGC–3

Answer 51

The answer to this question is D because suitable primers have a high GC content and have G or C base pairs at the 5 and 3 ends.

Question 52

In which phase of meiosis does nondisjunction occur? A. Anaphase I B. Metaphase II C. Prophase I D. Telophase II

Answer 52

The answer to this question is A because, by definition, nondisjunction is the failure of homologous chromosomes to separate during anaphase I of meiosis or the failure of sister chromosomes to separate during anaphase II of meiosis.

Question 53

Euchromatin vs heterochromatin

Answer 53

Euchromatin is prevalent in cells that are active in the transcription of many of their genes while heterochromatin is most abundant in cells that are less active or not active.

Question 54

Actin filaments are what type of filaments?

Answer 54

Microfilaments

Question 55

Is bicarbonate and CO2 found more in the blood plasma or the erethrocytes?

Answer 55

The erethrocytes

Question 56

What are integrins?

Answer 56

Integrins are transmembrane receptors that modulate cell-to-extracellular matrix interactions. Specifically, these proteins often attach the cell to collagen and fibronectin fibers.

Question 57

What are cadherins?

Answer 57

adherins are transmembrane proteins which play a primary role in cell-to-cell adhesion, forming adherens junctions to bind cells within tissues together.

Question 58

Function of calcitonin

Answer 58

Released from Thyroid gland. Calcitonin decreases plasma concentrations of Ca2+ by exerting a number of effects. One key example is that calcitonin stimulates bone formation by increasing osteoblast activity and decreasing osteoclast activity. The antagonist hormone to calcitonin is parathyroid hormone (PTH), which acts to increase plasma Ca2+ concentrations by (among other things) decreasing bone formation by osteoblasts and increasing bone degradation by osteoclasts. Thus, a drug which mimics parathyroid hormone would increase osteoclast activity.

Question 59

What is the antagonist to Calcitonin?

Answer 59

The antagonist hormone to calcitonin is parathyroid hormone (PTH), which acts to increase plasma Ca2+ concentrations by (among other things) decreasing bone formation by osteoblasts and increasing bone degradation by osteoclasts. Thus, a drug which mimics parathyroid hormone would increase osteoclast activity.

Question 60

What ribosome subunits do eukaryotes contain?

Answer 60

Question 61

What ribosome subunits do prokaryotes contain?

Answer 61

Question 62

What is commensalism?

Answer 62

When one species benefits but the other species is neither helped nor harmed, that is commensalism.

Question 63

What is parasitism?

Answer 63

Parasitism benefits one species at the cost of harm to another.

Question 64

What is competition in evolution?

Answer 64

Competition is when two species compete for access to a limited resource.

Question 65

What is mutualism?

Answer 65

Mutualism requires that both species benefit.

Question 66

Following puberty, the testes begin producing large amounts of testosterone. After production, the testosterone: A. is stored in secretory granules until needed to be secreted in response to declining plasma testosterone concentrations. B. diffuses into the circulatory system and is transported around the body while bound to a plasma protein. C. is confined to the nucleus of the cells were it is produced, where it upregulates genes associated with secondary sex characteristics in males. D. is transported to target tissues, where it binds to cell surface receptors and triggers a second messenger cascade.

Answer 66

B is correct. Remember that testosterone (shown below) is a steroid hormone. As such, it can freely diffuse through cell membranes. Also, as a hormone, testosterone is transported throughout the body in the circulatory system, not confined to the nuclei of cells in the testes. Testosterone must bind to a transport protein since it is not hydrophilic and thus cannot simply dissolve in the blood plasma directly.

Question 67

Differences in anode vs Cathode in different cells

Answer 67

In a galvanic (voltaic) cell, the anode is considered negative and the cathode is considered positive. This seems reasonable as the anode is the source of electrons and cathode is where the electrons flow. However, in an electrolytic cell, the anode is taken to be positive while the cathode is now negative.

Question 68

What charge is the cathode in an Isoelectric focusing setting?

Answer 68

Negative

Question 69

A chemist looking to enhance parenteral nutrition attempts to create amino acids and sugars in the lab that are produced naturally in the body. He finds that his workups consistently produce racemic mixtures of the amino acids that the body normally synthesizes and uses in only a single enantiomeric form. The most likely reason for this distinction is that: A. the enzymes the body uses are highly substrate-specific in their active sites, only interacting with particular kinds of functional groups. B. the solvents used for workup in the lab are less selective than the enzymes in the body. C. the enzymes the body uses are typically stereospecific and only produce one enantiomer. D. the reactions in the lab have higher activation energies requiring much higher temperatures than 37ºC.

Answer 69

C is correct. Many of the enzymes used in the body are stereospecific – they will only react with one particular stereoisomer form of a molecule and will only catalyze a reaction that produces a particular isomer of the product. Often drugs are administered as a racemic mixture because the workup in the lab produces such a mixture even though only one of the isomers has any biological effect.

Question 70

Sympathetic response with pupils

Answer 70

pupil dilation

Question 71

Lytic vs Lysogenic

Answer 71

A temperate bacteriophage has both lytic and lysogenic cycles. In the lytic cycle, the phage replicates and lyses the host cell. In the lysogenic cycle, phage DNA is incorporated into the host genome, where it is passed on to subsequent generations.

Question 72

Nonsense mutation

Answer 72

A nonsense mutation results in a premature stop codon and a truncated, often nonfunctional protein.

Question 73

Missense mutation

Answer 73

a point mutation where a single nucleotide changes the amino acid of the codon.

Question 74

Deletion mutation

Answer 74

In a deletion, part of a chromosome or DNA sequence is lost, which is not the case in this example.

Question 75

What is the 5' UTR?

Answer 75

The 5'-untranslated region (5′-UTR) is the region of mRNA that is directly upstream from the initiation codon. This region is important for the regulation of translation of a transcript; from this information alone, we know that the 5'-UTR must be transcribed. However, as it is the "untranslated" region, we can conclude that this region is not translated or only partially translated into a protein.

Question 76

How do you find the number of base pairs in an mRNA?

Answer 76

A mature mRNA consists of a 5’-cap (one base pair), the 5' UTR, coding regions, the 3' UTR, and a poly(A) tail.

Question 77

Coding DNA vs Non-Coding DNA

Answer 77

genes vs base pairs

Question 78

Arrange the following in increasing order of compactness. I. Nucleosome II. Heterochromatin III. Euchromatin IV. DNA helix A. IV, I, II, III B. III, I, II, IV C. I, III, IV, II D. IV, III, II, I

Answer 78

D is correct. Examining the choices, we can see right away that a DNA helix will be the least compact structure given and should be listed first (eliminate choices B and C). Now we need only to compare the remaining structures. Beginning with structure I (a nucleosome), note that according to the information in paragraph 3, nucleosomes are approximately 11-15 nm in diameter. These form the fundamental repeating units of eukaryotic chromatin, meaning that they are more compact than either chromatin structures and should be listed last. Note that euchromatin is less coiled then heterochromatin

Question 79

What does albumin do?

Answer 79

Serum albumin is the most abundant blood plasma protein and is produced in the liver and forms a large proportion of all plasma protein. ... Serum albumins are important in regulating blood volume by maintaining the oncotic pressure (also known as colloid osmotic pressure) of the blood compartment.

Question 80

What is specific activity a measure of?

Answer 80

The enzyme units per milligram of total protein in a solution

Question 81

Relationship between Kd and the affinity of a ligand?

Answer 81

The lower the Kd, the higher the affinity towards the ligand.

Question 82

What is Kd?

Answer 82

The binding association constant. The dissociation constant represents the ligand concentration that is necessary to achieve 50% binding.

Question 83

Adaptive Radiation

Answer 83

adaptive radiation is a process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, creates new challenges, or opens new environmental niches.

Question 84

Which participant in the electron transport chain has the greatest attraction for electrons? FAD NAD+ Oxygen Cytochrome c

Answer 84

FAD and NAD+ do not directly donate electrons to the electron transport chain—it is their reduced forms that do. Electrons move to a slightly more electronegative carrier as the electrons pass through each step in the electron transport chain. Therefore, the final electron acceptor of this chain, oxygen, has the greatest attraction for electrons.

Question 85

The cell type in the male reproductive system that is most analogous to the female ovum is the: spermatogonium. primary spermatocyte. spermatid. spermatozoon.

Answer 85

The mature ovum is the female gamete that has completed meiosis and contains the haploid number of maternally derived chromosomes. This makes it most analogous to spermatozoa, the mature male gametes that contain the haploid number of paternally derived chromosomes.

Question 86

Exocrine glands vs Endocrine glands

Answer 86

Exocrine glands secrete their products through ducts; endocrine glands release their products into the bloodstream.

Question 87

Uric acid enters the urine both through filtration and secretion in the kidney. The process of filtration of uric acid in the kidney takes place in the: glomerulus. loop of Henle. distal convoluted tubule. proximal convoluted tubule.

Answer 87

Filtrate is formed as fluid passes from the glomerular capillaries through the glomerular membrane into the Bowman’s capsule. This region of the nephron is known as the glomerulus.

Question 88

Are D or L amino acids more commonly found in humans?

Answer 88

L

Question 89

Difference between microtubules and microfilaments?

Answer 89

The main difference between microtubules and microfilaments is that microtubules are long, hollow cylinders, made up of tubulin protein units whereas microfilaments are double-stranded helical polymers, made up of actin proteins

Question 90

What are the stop codons? What is the start codon?

Answer 90

UAG UAA UGA AUG

Question 91

Gene vs Allele

Answer 91

A Gene is a portion of DNA that results in a certain trait. An Allele is a version of a gene.

Question 92

In vivo vs in vitro

Answer 92

In vivo means that it is done inside of a living thing. In vitro means that it's done within a test tube.

Question 93

After a section of a DNA strand containing a UVR-induced lesion is removed and resynthesized, the newly synthesized strand is rejoined to the remainder of the DNA strand by what type of bond? A. Disulfide B. Hydrogen C. Peptide D. Phosphodiester

Answer 93

The answer to this question is D because phosphodiester bonds link the 3ʹ carbon atom of one deoxyribose and the 5ʹ carbon atom of another deoxyribose within the DNA molecules.

Question 94

secretory proteins are synthesized in the \_\_\_\_\_?

Answer 94

rough endoplasmic reticulum

Question 95

folding of secretory proteins occurs in the \_\_\_\_\_\_\_\_?

Answer 95

rough endoplasmic reticulum

Question 96

What is Ubiquitination?

Answer 96

Ubiquitination targets a protein for degradation by a proteasome.

Question 97

Vasopressin regulates the insertion of aquaporins into the apical membranes of the epithelial cells of which renal structure? A. Collecting duct B. Proximal tubule C. Bowman’s capsule D. Ascending loop of Henle

Answer 97

The answer to this question is A because vasopressin regulates the fusion of aquaporins with the apical membranes of the collecting duct epithelial cells.

Question 98

A prion is best described as an infectious: A. prokaryote. B. transposon. C. protein. D. virus.

Answer 98

The answer to this question is C because a prion is an abnormally folded protein that induces a normally folded version of the protein to also adopt the abnormal structure, which is often deleterious

Question 99

Under anaerobic conditions, how many moles of ATP are produced from each mole of glucose

Answer 99

2

Question 100

In humans, eggs and sperm are most similar with respect to: A. cell size. B. genome size. C. the time required for development. D. the numbers produced by a single individual.

Answer 100

The answer to this question is B because both eggs and sperm contain a haploid number of chromosomes and therefore they are most similar with respect to their genome size.

Question 101

What are lysosomes?

Answer 101

lysosomes are defined as membrane-bound organelles that contain hydrolytic enzymes activated by a low pH

Question 102

Where in the human male reproductive system do the gametes become motile and capable of fertilization? A. Testis B. Urethra C. Epididymis D. Prostate gland

Answer 102

The answer to this question is C because sperm, produced in the seminiferous tubules of the testes, completes maturation and becomes motile in the epididymis.

Question 103

What is the Hill coefficient and what does it tell us?

Answer 103

A Hill coefficient of 1 indicates independent binding, a value of greater than 1 shows positive cooperativity binding of one ligand facilitates binding of subsequent ligands at other sites on the multimeric receptor complex

Question 104

Which type of inhibitor does NOT alter the KM/Vmax ratio of an enzyme? Competitive Uncompetitive Noncompetitive Mixed

Answer 104

Uncompetitive uncompetitive inhibitors do not alter the slope of the Lineweaver–Burk plot, which is equal KM/Vmax.

Question 105

Convergent evolution

Answer 105

defined as a process whereby distantly related organisms independently evolve similar traits to adapt to similar needs Shark and Dolphin

Question 106

Kallman Syndrome is a disease in which gonadotropin-releasing hormone producing neurons fail to migrate from the olfactory area to the hypothalamus during embryonic development. Which endocrine axis is disrupted in individuals with Kallman Syndrome? A. The stress axis B. The growth hormone axis C. The thyroid axis D. The reproductive axis

Answer 106

The answer to this question is D because gonadotropin-releasing hormone regulates pituitary gonadotropin (luteinizing hormone and follicle-stimulating hormone) secretion. Thus, if gonadotropin-releasing hormone is not able to regulate luteinizing hormone and follicle-stimulating hormone secretion from the pituitary, the reproductive axis will remain quiescent. I

Question 107

Which statement correctly identifies an enzyme involved in DNA replication and describes its primary function? A. Ligase catalyzes the binding of RNA primers to DNA via phosphodiester bonds. B. Primase catalyzes the replacement of RNA primer nucleotides with DNA nucleotides. C. Helicase catalyzes the separation of the parent DNA strands at the origin of replication. D. Topoisomerase catalyzes the joining of adjacent Okazaki fragments into a continuous strand of DNA.

Answer 107

The answer to this question is C because during DNA replication, helicase catalyzes the unwinding and separation of the parental DNA strands, so that each can be replicated.

Question 108

Does histone acetylation lead to coiling or uncoiling? What about deacetylation?

Answer 108

Acetylation leads to uncoiling and more transcription. Deacetylation leads to more coiling and less transcription

Question 109

The adrenal medulla is part of which branch(es) of the peripheral nervous system? A. The somatic nervous system only B. The sympathetic branch of the autonomic nervous system only C. The parasympathetic branch of the autonomic nervous system only D. Both the sympathetic and the parasympathetic branches of the autonomic nervous system

Answer 109

The answer to this question is B because the adrenal medulla secretes epinephrine and norepinephrine in response to short-term stress. Reactions to short-term stress are mediated by the sympathetic branch of the autonomic nervous system.

Question 110

Imprinted gene

Answer 110

imprinted genes are expressed in a parent-specific manner.

Question 111

Certain viruses contain RNA as their genetic material. One of the ways these RNA viruses replicate themselves is to: A. code for or carry a transcriptase that copies viral RNA. B. infect microorganisms possessing RNA as their genetic material. C. alter the host cell’s polymerase in order to synthesize progeny viral RNA from the viral RNA template. D. stimulate the transcription of specific sequences of the host’s DNA, which, in turn, direct the assembly of viral particles.

Answer 111

The answer to this question is A because RNA viruses require a type of transcriptase (reverse transcriptase) to replicate themselves.

Question 112

Large amounts of protein are found in the urine of a patient. Based on this information, which portion of the nephron is most likely malfunctioning? A. Collecting duct B. Distal tubule C. Glomerulus D. Loop of Henle

Answer 112

The answer to this question is C because in healthy individuals, the structure of the glomerular capillaries prevents the entry of large molecules, such as proteins, into the filtrate.

Question 113

Mucous secretions in the respiratory tract inhibit microbial infections. These secretions are produced by which of the following tissue types found in the lungs? A. Smooth muscle B. Epithelial C. Nervous D. Connective

Answer 113

The answer to this question is B because epithelial cells are specialized cells for secretion and are present in the respiratory tract.

Question 114

What is a signal sequence domain?

Answer 114

Signal sequence domains are protein domains required for proteins that are directed toward secretory pathways

Question 115

What is a nuclear factor?

Answer 115

nuclear factors are the only elements that vary in different cells and therefore can confer both temporal and spatial regulation of their target genes.

Question 116

Cancer cells most likely have an abnormality in their: DNA. rRNA. mitochondria. lysosomes.

Answer 116

DNA (A) in cancer cells typically contains an abnormality (mutation).

Question 117

Pulmonary arterial blood differs from the aortic blood because it has: more O2, less CO2, and higher pH. more O2, more CO2, and higher pH. less O2, more CO2, and lower pH. less O2, less CO2, and higher pH.

Answer 117

Blood in the pulmonary artery is lower in oxygen, higher in CO2 and has a lower pH than arterial blood in the aorta. This is because the blood in the pulmonary artery, unlike blood in other arteries, is essentially the same as venous blood. It has passed through the tissues of the body where it has given up oxygen and taken on CO2. It has been pumped through the right side of the heart from the veins and headed for the lung where it will become oxygenated and will dispose of its CO2 load. Venous blood is lower in pH than arterial blood due primarily to the CO2 it carries.

Question 118

Contraction of the diaphragm results in a: more negative IPP and inspiration. more negative IPP and expiration. more positive IPP and inspiration. more positive IPP and expiration.

Answer 118

The diaphragm is a muscular partition between the abdominal and thoracic cavities. It is dome-shaped at rest curving up toward the lungs and heart. It flattens when it contracts during inspiration. Because it is anchored around its edges to the ribs and spine, when the diaphragm contracts the volume of the thoracic cavity increases. This decreases the pressure (IPP) in the pleural cavity between the thoracic wall and the lung. Fresh air flows in to equalize the pressure inflating the lung.

Question 119

In comparison with the wall of the right ventricle of the heart, the left ventricular wall is: thinner and generates a higher pressure when it contracts. thinner and generates a lower pressure when it contracts. thicker and generates a higher pressure when it contracts. thicker and generates a lower pressure when it contracts.

Answer 119

The difference in size between the thin wall of the right ventricle and the thick wall of the left ventricle is dramatic when viewed in cross section. The peak pressure in the left ventricle is 120 mmHg while the peak pressure in the right ventricle is only 25 mmHg. The right ventricle pumps blood through the lungs. The left ventricle pumps blood through the entire rest of the body. The difference in the size of the lung compared to the rest of the body suggests that the left ventricle develops more pressure and has a thicker wall than the right. The organs through which the left ventricle pumps blood are farther away from the heart than the lungs and resistance in a tube is inversely proportional to the length of the tube. This would also suggest a thicker wall for the left ventricle and greater pressure. The correct answer is choice C, that the left ventricle has a thicker wall and develops more pressure than the right.

Question 120

The pancreas produces which of the following substances for the digestive system? Bile salts Emulsifier Gastric juices Proteolytic enzymes

Answer 120

The pancreas produces several proteolytic enzymes, which are released into the small intestine where they are converted to their active forms of trypsin, chymotrypsin, and carboxypeptidase.

Question 121

What is the rate limiting step in Glycolysis?

Answer 121

Frc 6 phosphate to Frc 1,6 BPhosphate via PFK-1

Question 122

What is the rate limiting step in the Citric Acid Cycle?

Answer 122

Isocitrate to α-ketoglutarate via isocitrate dehydrogenase

Question 123

Gram positive vs Gram negative

Answer 123

The purple bacteria are known as Gram-positive Bacteria. The pink bacteria are known as Gram-negative Bacteria. These colors appear with the addition of a specific stain. A gram-positive bacteria has 3 layers while a gram-negative bacteria has 5 layers.