Additional Questions I Got Wrong

Which of the following viruses should be able to reproduce successfully if they carry RNA-dependent RNA polymerase into their host cell?

(+) RNA virus (-) RNA virus ds DNA virus

A retrovirus is a:

(+) RNA virus that undergoes the lysogenic cycle, and so must encode reverse transcriptase in the genome.

What linkages does starch have?

(1,6) linkages

What is the role of phosphodiesterase?

- cleaves phosphodiester bonds --> nucleic acid digestion

Which of the following are functions performed by parietal cells?

-Acid production -Secretion of intrinsic factor, required for the absorption of vitamin B12

Which of the following compensatory mechanisms would be expected to occur in an individual experiencing prolonged ketoacidosis?

-Increased ventilation rate -Decreased bicarbonate excretion - With prolonged ketoacidosis, bicarbonate excretion at the kidney would be decreased (e.g. less bicarbonate would be eliminated and more reabsorbed) in order to promote an increase of blood pH to normal levels

What are the four steps of translating a sound wave to a nerve impulse?

1) Movement of auditory ossicles 2) Pressure changes produced within the inner ear 3) Displacement of basilar membrane 4) Movement of hair cells with respect to tectorial membrane

If an X-linked recessive disorder affects 1/1,000,000 females in a population, what is the expected frequency of affected males in the population?

1/1000 Because a woman affected with an X-linked recessive disorder must have two affected X chromosomes, the frequency of the affected X chromosome in the population can be determined by taking the square root of the frequency of affected females which equals 10-3, or 1/1000. The frequency of affected males in the population for this disorder corresponds to the frequency of the affected X chromosome in the population, since the male gender genotype is XY. Therefore, 1/1000 is the correct frequency of the affected males.

The calcium in the presynaptic terminal that triggers transmitter release reaches which of the following concentrations?

10 -6 to 10 -5 M

Lab techniques - A single plasmid is isolated from bacterial cells. When the plasmid is digested with a restriction enzyme and then subjected to gel electrophoresis, two bands are observed on the gel. How many restriction sites for this enzyme are present in this plasmid?

2 Plasmids are circular DNA, so if the plasmid is cut in two places it will produce two fragments. The general rule when cutting circular DNA with restriction enzymes is that the number of fragments you end up with is the same as the number of restriction sites.

The missing karyotype data from Table 2 should read:

44 autosomes, 46 centromeres, 92 telomeres, 21 medium size chromosomes HC7W is a human cell line, and should therefore have 46 total chromosomes; 44 autosomes and 2 sex chromosomes (choice A can be eliminated). Each chromosome should have one centromere (for a total of 46, choice B can be eliminated) and two telomeres (for a total of 92). Table 2 lists 10 large chromosomes and 15 small chromosomes. If there are 46 chromosomes total, there must be 21 medium size chromosomes (choice C is correct, and choice D is wrong).

Which of the following is a best example of an opportunistic bacterial infection?

A Staphlycoccal infection in a wound

Enzymes are proteins that catalyze specific chemical reactions within a cell. Which of the following statements about enzymes is/are true?

A common means of regulating enzyme activity is through phosphorylation of the enzyme.

Which of the following changes in vitamin consumption is likely to result in a decrease in visual acuity?

A decrease in consumption of fat soluble vitamins

Prions do not follow the principles of the Central Dogma and are referred to as self-replicating proteins. Which of the following best describes their means of replication?

A disease-causing version of the protein acts as the folding template to cause a regular version of the protein to become misshapen.

A patient with bulimia begins to develop lethargy which is believed to be related to metabolic alkalosis. Which of the following best explains this finding?

A left-shift in the oxygen saturation curve for hemoglobin

Catalytic receptors operate via which of the following?

A ligand binds, triggering enzyme activity on the cytoplasmic side of the membrane.

Which of the following would most affect the Km of an enzyme?

A mutation in the active site The Michaelis constant (Km) is the concentration of substrate necessary for a reaction to achieve ½ Vmax. It is also inversely proportional to affinity of the enzyme for its substrate. Therefore a mutation in the active site of the enzyme is likely to affect the Km for a given reaction.

Cells are infected by a virus and express a cytoplasmic viral antigen. Which of the following describes how the antigen will be presented?

A peptide from the antigen will be expressed on Class I MHC

A pregnancy test is an ELISA set up to detect human chorionic gonadotropin (hCG), a hormone specific to pregnancy. How would this ELISA be configured?

A primary antibody specific for hCG, blood or urine sample, a secondary antibody specific for hCG ELISA tests utilize the specificity of antibodies to identify antigen or antibody in a patient's blood or urine sample. hCG in this case is acting as the antigen; anti-hCG antibodies are fixed to a microtiter well plate, and the blood or urine sample is applied. If hCG is present, it will bind to the primary antibody. A wash removes any unbound substances. The secondary antibody is specific to a different region on hCG and is covalently bound to an enzyme that produces a color change; the secondary antibody will bind to hCG and application of the substrate will produce the color change.

In which of the following situations would there be the greatest yield of products at equilibrium following the addition of an enzyme?

A reaction with less stable reactants and large activation energy

Inbreeding

A selective breeding method in which two individuals with identical or similar sets of alleles are crossed.

Which of the following is the first event in transduction of light by rod cells?

A sodium channel closes and the cell hyper-polarizes

Which of the following best describes the transmission of an action potential through a skeletal muscle cell based on stimulation from the neuromuscular junction (NMJ)?

ACh released at the neuromuscular junction triggers an end plate potential, threshold is reached, action potential travels along transverse tubules, sarcoplasmic reticulum is depolarized

What is aneuoploidy?

Abnormal number of chromosomes.

Atropine is a medication sometimes used to treat symptomatic bradycardia (slow heart rate). What is the most likely mechanism of action of atropine?

Acetylcholine antagonist

Which of the following structures connects the gastrocnemius muscle in the calf to the calcaneus, a bone in the ankle?

Achilles tendon

Which of the following properties is shared by both smooth and skeletal muscle?

Actin-myosin cross-bridging causes contraction

Epigenetics is the heritable increases or decreases in gene expression due to environmental (among other) causes. One of the mechanisms involved this differential expression is DNA methylation. What is the most likely mechanism for this process?

Addition of a methyl group to cytosine, resulting in methyl-cytosine base-pairing with guanine

Which of the following forms of eukaryotic post-transcriptional modification is most critical for ribosome association with an mRNA transcript?

Addition of the 5' cap The 5' cap contains the ribosome binding site in eukaryotes and is critical for ribosome association (choice D is correct).

What is albumin?

Albumin is a protein made by your liver. Albumin helps keep fluid in your bloodstream so it doesn't leak into other tissues.

Angiotensin II acts as a vasoconstrictor to increase blood pressure in the short term, but it also triggers the release of what hormone to perpetuate this effect?

Aldosterone

What is the role of serotonin?

Alters the amount of neurotransmitter released by the presynaptic cell, amplifying the response. Vasoconstriction

The following participate in gas exchange:

Alveolus Alveolar duct Respiratory bronchiole

What are the requirements for a complex transposon?

An IS element and one or more genes

What is antithrombin III?

An anticoagulant that prevents excessive blood clot formation

What does an endocrine gland do?

An endocrine gland is a ductless gland whose secretory products, hormones, are picked up by capillaries.

What does an exocrine gland do?

An exocrine gland, which secretes products into ducts to travel to a body cavity or the body surface.

Low blood pressure and low blood volume trigger which of the following?

An increase in aldosterone followed by a subsequent increase in ADH

Which of the following are hormones released by the posterior pituitary?

Antidiuretic hormone and oxytocin

Which of the following vessels carry oxygen-rich blood?

Aorta Umbilical vein Pulmonary vein The aorta carries oxygenated blood from the left ventricle into the systemic circulation (Item I is true). The umbilical vein returns oxygenated blood from the placenta to the fetal heart (Item II is true). The pulmonary veins return oxygenated blood from the lungs to the left atrium (Item III is true).

What is the relationship between the amplification of force and area of the respective components of the ear?

As the area decreases, the force amplification increases

Kinesin plays a significant role in mitosis and helps in the spindle apparatus assemble. In which direction does kinesin travel and in which phase of mitosis does its activity begin?

Away from the MTOC; prophase

The major cell type involved in the humoral immune response is the

B cell

What are backcrosses used for?

Backcrosses are generally used to eliminate or elevate a particular gene's frequency in the progeny population. In order to work, the progeny must repeatedly be crossed back with parental generations in order to get the genomic frequency desired. In any case, "back"cross implies that the individual is crossed "back" to a member of the previous generation

Damage to which component of the ear would be most likely to alter a person's perception of pitch?

Basilar membrane

How do bipolar neurons differ in structure from multipolar neurons?

Bipolar neurons have one dendrite-like structure whereas multipolar neurons have many dendrites

Mitosis occurs in which human cell type?

Bone marrow cells

Follicle stimulating hormone (FSH) and luteinizing hormone (LH) have what comparable effect in both males and females?

Both FSH and LH are involved in oogenesis, spermatogenesis, and the secretion of sex steroids.

Which of the following do peptide and steroid hormones have in common?

Both bind to protein effectors Both peptide and steroid hormones bind to protein receptors to impact a given cell

The pattern of inheritance for mitochondria is called maternal inheritance. Which of the following statements is true about maternal inheritance for females?

Both gametes contribute equally to the genome, and the egg provides the rest of the zygote.

A researcher working on an isolated island discovers what she thinks is a new species of bird. It has a longer beak than most birds on the island and different color plumage. Its song is different from the songbirds on the island. Which of the following tests would be most helpful in determining if the bird is a new species or not?

Breed the bird with other island birds The defining characteristic of distinct species is the inability to interbreed

What is heart rate determined by?

By the slow-influx of sodium through leak channels in the cells of the SA node; inhibiting these would further decrease heart rate since the cells would reach threshold less often.

The removal of MHC I from somatic cells would have the most direct impact on what cell-mediated immune system function?

CD8 T cells would no longer be able to recognize virally infected cells

Osteoclasts are inhibited as part of bone remodeling by which hormone?

Calcitonin

What is the role of calcitonin? Calcitriol?

Calcitonin is secreted in response to high serum calcium levels; it inhibits osteoclast-mediated bone breakdown and increases osteoblast-mediated bone formation. Parathyroid hormone and calcitriol increase bone reabsorption and decrease bone formation.

What two components are unique to the regulation of smooth muscle?

Calmodulin and myosin light chain kinase

Which of the following immune responses is characteristic of a viral infection leading to pneumonia?

Cell-mediated immunity, involving the activation of cytotoxic T cells

Which of the following plays a role in uncompetitive inhibition?

Change in the shape of the inhibitor binding site

Warkany syndrome is a perinatal lethal disease caused by nondisjunction. Which of the following is another name for Warkany syndrome?

Chromosome 8 trisomy syndrome Nondisjunction is a meiotic anaphase separation defect. It leads to too many or too few chromosomes (also known as aneuploidy) in gametes and resultant zygotes. Trisomy is when a cell contains three copies of a given chromosome, instead of two, and is an example outcome of nondisjunction (choice B is correct).

Describe the two classes of MHC molecules

Class I presents endogenous protein antigens (made by the cell) Class II presents exogenous protein antigens derived from the extracellular environment and internalized by phagocytosis

Damage to which one of the following would be most likely to hinder the detection of high-frequency, but not mid-frequency sound by the ear?

Cochlea Damage to the auditory nerve or to the auditory ossicles (malleus, incus, and stapes) would hinder the detection of all frequencies since the nerve would be unable to send impulses to the brain and the ossicles would be unable to transmit sound waves to the inner ear, and neither of these functions is pitch-specific. Damage to the outer ear would not hinder pitch-specificity at all. The cochlea is a large, curled structure in the inner ear, along which the basilar membrane is stretched. The basilar membrane supports the hair cells of the ear (the sound receptors), and vibrates in sound waves. However, since one end of the basilar membrane is considerably thicker than the other, maximum vibration of a particular area depends of the frequency of the wave stimulating the membrane. Damage to the cochlea is the most likely injury to hinder the detection of particular frequencies.

Fluoroquinolones are a class of antibiotics that inhibit DNA gyrase. Which of the following would be inhibited?

Condensing of DNA Gyrase is an enzyme specific to prokaryotes that maintains bacterial DNA in its supercoiled helical state. Unwinding of DNA is accomplished primarily using helicase and topoisomerase. Okazaki fragments are connected using DNA ligase. Ribosomal separation results when a release factor enters the A site, and peptidyl transferase hydrolyzes the bond between the last tRNA and the completed peptide chain. This occurs after translation, not transcription.

Which of the following is true of the lens of the eye and the image it produces, if the light received comes from an object at a distance greater than two focal lengths away?

Convergent lens with an inverted real image

Which of the following is the correct pathway of light entering the anterior surface of the eye leading to stimulation of the optic nerve? (4 steps)

Cornea --> anterior chamber--> lens--> retina

What steps are necessary to replicate a (-)RNA virus?

Create a (+)RNA copy of the genome using RNA-dependent RNA polymerase then replicate (-)RNA copies from that template using the same enzyme.

HIV is a +RNA retrovirus whose genome can be directly translated to form a variety of viral proteins even before insertion into the host's genome. Which of the following enzymes would be needed AFTER insertion into the host genome to transcribe the mRNA for viral proteins?

DNA dependent RNA polymerase The first part of the enzyme name ("___ dependent") describes what type of nucleic acid the enzyme uses as a template, and the second part of the enzyme name ("___ polymerase") describes the type of nucleic acid the enzyme synthesizes. Since this enzyme is synthesizing mRNA, it must be an RNA polymerase. The question asks for the enzyme needed AFTER the viral genome is inserted into the host genome. In order to be inserted into the host genome, the viral genome must have been converted to its DNA version by reverse transcriptase (an RNA dependent DNA polymerase). If the viral genome is now in its DNA version and is inserted in the host genome, the enzyme transcribing it must be DNA dependent (use DNA as a template).

A codon is a segment of an mRNA molecule that codes for one amino acid in a polypeptide chain formed during protein synthesis. Which of the following correctly describes the chain of events that occurs in the synthesis of a polypeptide?

DNA generates mRNA; mRNA moves to the ribosomes, where a tRNA anticodon binds to an mRNA codon, causing amino acids to join together in their appropriate order.

How does standard DNA sequencing differ from running a polymerase chain reaction to synthesize DNA?

DNA sequencing utilizes ddNTPs which lack the 3'OH group. This terminates polymerization, creating fragments. DNA sequencing does use ddNTPs which randomly stop polymerization and thus create fragments of various lengths. The fragments are run on a gel so the positions of the constituent As, Ts, Gs, and Cs can be visualized. Radiolabeling is part of sequencing as is electrophoresis.

Which of the following is most likely to cause an abnormal increase in the level of serum glucose?

Damage to the endocrine function of the pancreas

Which of the following is an example of feedback inhibition?

Decreased activity of PFK due to elevated levels of phosphoenolpyruvate, a glycolytic intermediate Feedback inhibition involves the decrease in activity of an enzyme by binding to a downstream product

Macrophages express both classes of MHC molecules (type I and type II) on their plasma membranes. Upon infection of a macrophage with adenovirus, a viral protein is generated that binds specifically to MHC type 1 molecules. As a result, these MHC molecules are retained in the endoplasmic reticulum and not transported to the plasma membrane. Which of the following is the most likely consequence of adenoviral infection?

Decreased likelihood of cytotoxic T-cell destruction of an infected macrophage Any cell infected with a virus will process viral antigens and present them in the context of an MHC type I molecule on the cell surface. Cytotoxic T cells will recognize "non-self" viral antigen complexed with "self" MHC type I and will destroy the cell. If the infected macrophage's MHC type I molecules are prevented from moving to the cell surface by the virus, the macrophage cannot communicate its state of infection to cytotoxic T cells and will be spared

Depletion of extracellular calcium would have which of the following effects on synaptic transmission?

Decreased neurotransmitter release

Which of the following is the most accurate, from least organized to most organized?

Deoxyribose, nucleoside, nucleotide, DNA helix, nucleosome, chromatin

In the creation of an expression vector, what step is necessary to prepare both a gene of interest and the plasmid that will carry it for ligation?

Digest both genetic sequences with the same restriction endonuclease. To create ends that can be connected, the same restriction endonuclease must be used to both open the plasmid and digest the ends of the gene of interest so it can be ligated into the plasmid. Both pieces need to be double-stranded, not single. Proofreading of any type would have already been done in synthesizing the sequences. At this stage, the genetic constructs are already isolated from proteins so proteases are not needed.

Why is the first step of apoptosis to disassemble the cytoskeleton?

Disassembling the cytoskeleton allows the cell to shrink, thus minimizing damage to neighboring cells as it is destroyed.

Which of the following antibody components does NOT contribute to its antigen specificity?

Disulfide bonds

Inability during aging to hear high frequency sounds rather than low frequency sounds.

Due to: increased loss of hair cells at the base of the basilar membrane

How does freezing-point depression work to defy the thermodynamic principle of entropy?

During freezing, solutes are first organized into an array before the solvent forms crystals; thus higher solute concentrations require lower temperatures to freeze.

What happens during gel electrophoresis?

During gel electrophoresis, negative DNA moves to the positive end of the gel in a size dependent manner. Small fragments of DNA move quickly and large fragments move slowly.

When is a neuron in its relative refractory period?

During hyperpolarization

A rapid HIV test is usually a test for the presence of HIV antibody in the subject's serum. Which of the following tests is most likely to be used as a rapid HIV test?

ELISA In an ELISA, a person's serum is applied to a plate to which HIV antigens have been attached. If anti-HIV antibodies are present in the serum, they bind to the HIV antigens. The plate is then washed, and a secondary antibody specific for human antibodies is applied. This secondary antibody is covalently bound to an enzyme that produces a color change upon application of its substrate, or to a molecule that will fluoresce

Negative feedback loop * important

Emotional input --> hypothalamus ---(corticotropin releasing factor)---> anterior pituitary---(ACTH)---> Adrenal Cortex --> cortisol (negative feedback to anterior pituitary and hypothalamus) So high cortisol, less ACTH

Synthesis of antibody proteins in eukaryotic cells is associated with what organelle?

Endoplasmic reticulum

The nuclear envelope makes the interior of the nucleus continuous with what other membrane-bound organelle?

Endoplasmic reticulum

How are peptidases activated in the duodenum?

Enterokinase converts trypsinogen from the pancreas into trypsin; trypsin then activates the other pancreatic enzymes.

Patients suffering a penetrating trauma to the chest from a gunshot or knife wound often have subsequent difficulty breathing. Which of the following is the most likely explanation?

Equalization of pressures between the interpleural space and the outside air

In diabetes mellitus, insulin is either not made in sufficient quantities or is not responded to appropriately by the body. Though the impact on the kidneys can be significant, which of the following would NOT be expected at noticeable levels in the urine of a diabetic?

Erythrocytes

Which of the following produces a strand of DNA in the 5' to 3' direction?

Eukaryotic DNA polymerase Prokaryotic DNA polymerase III Reverse transcriptase All three polymerases listed use a template strand to create a new strand of DNA. They do so by adding new nucleotides to the 3' end of the new strand (hence, the strand grows in the 5' to 3' direction). Reverse transcriptase differs from the DNA polymerases only in that is uses an RNA template instead of a DNA template to synthesis its new strand of DNA. However, it too adds new DNA nucleotides in the 5' to 3' direction.

Which of these is the primary source of calcium ions in smooth muscle?

Extracellular space

What is FISH?

FISH can identify a range of mutations including deletions, duplications, aneuploidy, and the presence of derivative chromosomes The FISH acronym stands for "fluorescence in situ hybridization". The FISH technique is used to search and find a specific DNA sequence on chromosomes. Fluorescent probes that bind to only those parts of the chromosome with which they show a high degree of sequence similarity are used to tag sequences of DNA fluorescent in situ hybridization

In a breeding program of endangered condors in a zoo, the breeders examine two loci and find that one male has a different allele at both of these loci than do the other nine animals (four females and five males) in captivity. Given this knowledge, the breeder's best course of action would be to:

Finding variation at two loci out of the thousands that are probably present in the condor genome is not enough of a reason to do anything without further analysis (choice A is correct and choices B and C are wrong).

On what part of the retina does the image focus on when you stare directly at something?

Fovea centralis

Which of the following statements is true?

Fructose-2,6-bisphosphate levels are reduced when glucose levels are low; this helps to drive gluconeogenesis forward When glucose levels are low, glucagon stimulates the enzyme that breaks down fructose-2,6-bisphosphate. This molecule typically stimulates glycolysis and inhibits gluconeogenesis, so it's absence due to increased breakdown inhibits glycolysis and stimulates gluconeogenesis, which is exactly what is needed when glucose levels are low

What is the cell wall made for plans and fungi?

Fungi - chitin Plants - cellulose

What does gas chromatography do?

Gas chromatography is used to separate very small molecular weight particles with different volatility.

What is gel electrophoresis?

Gel electrophoresis is used to separate native or denatured proteins by the length and charge of the polypeptide

Reaction coupling allows for:

Generation of products that would not normally be formed spontaneously.

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are ion channels which have activity modulated by cyclic nucleotides. A given HCN channel is inhibited by high levels of cAMP. Activating which G-protein cascade would increase activity of this channel?

Gi, which would inhibit adenylyl cyclase

What is located in the renal cortex:

Glomeruli are the beginning of the nephron, where filtration occurs, and proximal tubules are found directly after glomeruli; both are located in the renal cortex

What organelle would be most closely associated with exocytosis of newly synthesized secretory protein?

Golgi apparatus The secretory pathway passes through the ER to the Golgi, to secretory vesicles, to the exterior through exocytosis.

The following are a components of the Organ of Corti?

Hair cells Tectorial membrane Basilar membrane

How does the auditory cortex in the temporal lobe receive stimulation from the ear?

Hair cells contacting the tectorial membrane open ion channels to trigger release of neurotransmitter Perception of sound begins with sound waves vibrating the basilar membrane. This causes hair cells (mechanoreceptors) to come in contact with the tectorial membrane, and this contact opens ion channels in the hair cells. The cells depolarize and release neurotransmitter to stimulate the bipolar auditory neurons that run to the auditory cortex in the temporal lobe. Baroreceptors are not involved in this process.

Hemoglobin is an oxygen-carrying protein found in red blood cells. It is made up of four protein subunits that display cooperative binding. Myoglobin is also an oxygen-carrying protein, however it is found in muscle cells and it is made of only a single protein subunit. How would the saturation curves for hemoglobin and myoglobin compare?

Hemoglobin would have a sigmoidal curve while myoglobin would have a simple curve. Enzymes that display cooperative binding have sigmoidal curves. In order to display cooperative binding, a protein must be made up of more than one subunit. Since myoglobin is made of only a single subunit, it cannot display cooperative binding and would have a simple saturation curve.

Which of the following is not a component of the Bohr effect?

High serum PO2

The following hormone receptors contain transmembrane domains:

Hormones are signaling molecules released by cells, which travel through the bloodstream and bind to receptors at target cells in other parts of the body. calcitonin receptor, growth hormone receptors, cholecystokinin receptors (peptide hormones) EXCEPT: Cortisol, estrogen and testosterone is a steroid hormone; its receptor would be found in the cytoplasm and would not contain a transmembrane domain.

By which of the following mechanisms is the release of insulin primarily controlled?

Humoral The release of insulin is controlled primarily by the presence or absence of glucose in the blood plasma (humorally).

Which of the following best describes the state of a cell shortly after GABA is bound?

Hyperpolarized

Conn syndrome is characterized by the overproduction of aldosterone by the adrenal glands. In most cases, the syndrome is due to the presence of an aldosterone-secreting adrenal adenoma (a benign tumor). A patient with Conn syndrome is most likely to experience which of the following symptoms?

Hypertension resulting from increased reabsorption of Na+ at the distal convoluted tubule.

A drug is discovered that markedly increases hemoglobin's affinity for oxygen. What physiological situation is this drug mimicking?

Hyperventilation

What happens during hyperventilation?

Hyperventilation results in reduced blood carbon dioxide levels, which leads to an increase in blood pH and an increase in hemoglobin's affinity for oxygen.

If erythrocytes are placed into a hypertonic solution, they will:

If erythrocytes are placed into a hypertonic solution, they will shrivel. In a hypertonic solution, the extracellular environment has a higher solute concentration. Osmotic pressure would draw water out of the cell, making solutes more concentrated inside the cell, and making the cell shrivel.

Hemophilia is an X-linked recessive trait in humans. If a carrier female mates with the hemophiliac male, what is the probability they will have a daughter who does NOT have hemophilia?

If we assign D = normal and d = hemophiliac, the cross in the question stem is XDXd × XdY. If the offspring is female, she will receive the Xd chromosome from her father, and the probability of this is 0.5. To have a normal phenotype, she must receive the XD chromosome from her mother, and the probability of this is 0.5. Overall, the probability of having a normal daughter is (0.5)(0.5) = 0.25, (choice C is correct).

IMPORTANT** Eukaryotes running aerobic respiration net 30 ATP per glucose, while prokaryotes net 32 ATP. Why?

In eukaryotes, the electrons from glycolytic NADH must be shuttled from the cytosol into the mitochondrion, and bypass the first proton pump. In eukaryotes, glycolysis occurs in the cytosol, while the PDC, Krebs cycle, and electron transport occur in the mitochondria. The NADH from glycolysis is oxidized in the cytosol (so that NAD+ continues to remain available for glycolysis), and the electrons are shuttled into the electron transport chain. However, the electrons bypass the first proton pump (NADH dehydrogenase) and are delivered to coenzyme Q, the second molecule in the electron transport chain. This results in the movement of fewer protons out of the mitochondrial matrix, and thus less ATP made when the protons reenter the matrix through the ATP synthase. Prokaryotes run glycolysis, PDC, and the Krebs cycle in the cytosol, with all NADH immediately available to the first pump in their transport chain.

Which of the following is a difference between metaphase I in meiosis and metaphase in mitosis?

In meiotic metaphase I, tetrads line up along the cell's center while in mitotic metaphase individual replicated chromosomes line up.

Which of the following is necessary for prokaryotic translation?

In prokaryotes, the 30S and 50S subunits of the ribosome must come together for translation to occur but when they do they make a 70S ribosome. Eukaryotes have 80S ribosomes (although they are not necessary for prokaryotic translation). The Shine-Dalgarno sequence is the ribosome binding site in prokaryotes (similar to the Kozak sequence in eukaryotes) and without this the gene product cannot be translated. fMet (formylmethionine) is a modified methionine used as the first amino acid in all prokaryotic proteins. GTP is very similar to ATP but it contains a different purine base (guanine replaces adenine). Prokaryotic transcription uses GTP as its energy source, not ATP.

In terms of ATP, approximately how many glucose molecules would it take to translate a 60 amino acid polypeptide chain in a eukaryote undergoing aerobic respiration?

In terms of ATP, it would take 8 glucose molecules to translate a 60 amino acid polypeptide chain in a eukaryote undergoing aerobic respiration. Aerobic respiration in a eukaryote results in 30 ATP per glucose. Translation requirements are as follows (note that these are commonly referred to as "ATPs" but many are actually ATP-equivalents, including ATP and other high energy bonds like GTP): 2 ATP per AA-tRNA loading; 1 ATP to form the initiation complex; and 2 ATP per AA joining the peptide chain. Thus, for a 60 AA peptide it would require 239 ATP and ~ 8 molecules of glucose.

Where are antibiotics carried?

In the bloodstream

Where is actin in cells?

In the cytoplasm

HHV-8 is a Rhadinovirus and is remarkable since it has stolen numerous genes from host cells, including genes that code for complement-binding proteins, interleukin-6, BCL-2, cyclin-D, and a G protein-coupled receptor. What is the most likely mechanism by which this was accomplished?

Inaccurate provirus excision

Which of the following is the most likely effect of a eukaryotic transcription factor?

Increase the encounter rate of DNA with RNA polymerase

Compounds A and B react very slowly to form Compound C. Addition of a very small quantity of Enzyme X doubles the reaction rate. Addition of twice as much Enzyme X would most likely:

Increase the reaction rate by the same amount as the first addition of enzyme. Doubling the amount of enzyme doubles the number of available active sites, and so doubles the rate of the reaction. The addition of more active sites (without the addition of more substrate) will not lead to saturation, in fact it is the opposite. Reaction rate is clearly dependent on enzyme concentration; initially, at an enzyme concentration of zero, the reaction rate was stated to be "very slow". When enzyme was added, the reaction rate doubled. Enzymes have no effect on the equilibrium constant. They do not change the equilibrium point of a reaction, they only speed up the rate at which the reaction reaches equilibrium.

A patient suffering from menopause experiences decreased levels of estrogen due to decreased ovarian production. Which of the following lab results would be expected?

Increased FSH, increased GnRH

Which of the following occurs in the nephron in response to high pH?

Increased bicarbonate secretion

Which of the following statements regarding the microscopic structure of bone is correct?

Individual osteocytes communicate with one another via gap junctions.

What are 3 means by which prion infection can typically occur?

Inheritance Spontaneous mutation Consumption

Protein synthesis is primarily regulated at the level of transcription. Which of the following could lead to an increase in protein synthesis in a typical eukaryotic cell?

Inhibition of repressor binding to a gene regulatory region

A patient has suffered nerve damage which has impaired the contraction of his scalene muscles and results in difficulty breathing. Which of the following is most likely to be affected?

Inspiration This question is essentially asking what function the scalene muscles play in respiration and, as you are not required to know this function, is best answered by process of elimination. The elasticity of the chest wall, which is partially responsible for preventing collapse of the lungs, is a function primarily of bone and other connective tissue, and not any particular muscle group. Passive expiration is a passive process and no muscle contraction is required, and there is no reason to believe the function of the diaphragm will be directly affected by the impaired function of the scalene muscles. This leaves choice C: the scalene muscles, in addition to the sternocleidomastoid and others, are involved in inspiration.

Which of the following is an example of reciprocal regulation of glycogen metabolism?

Insulin stimulates glycogen synthase and inhibits glycogen phosphorylase. Reciprocal regulation occurs when a single molecule stimulates a pathway in one direction while inhibiting the pathway in the opposite direction. Insulin is released when blood sugar is high; it stimulates glycogen synthase (to store glucose as glycogen) and inhibits glycogen phosphorylase (the first enzyme in glycogen breakdown

The following are known mechanism of direct enzymatic regulation?

Interaction of the enzyme with downstream products Peptide hydrolysis Removal of a phosphate with the use of a phosphatase

Which of the changes occurs during defecation?

Internal anal sphincter is relaxed

Short tandem repeat analysis for DNA fingerprinting utilizes patterns of repetitive DNA within what part of the genome to identify individuals?

Introns Amplification via PCR is followed by electrophoresis and Southern blotting.

What is the function of p53 in normal cells?

It induces cell death in the event of aberrant cell division

Estrogen levels gradually increase throughout the first half of the menstrual cycle. Which of the following is true about estrogen?

It induces thickening of the endometrial wall.

Which of the following statements concerning thyroid hormone is true?

It is derived from amino acids and binds a receptor within the cell

Which of the following is true regarding Krebs cycle regulation?

It is inhibited by increased ATP levels.

Which of the following western blotting techniques correctly pairs the material used as a probe with the material being detected?

Labeled antibodies are used to detect certain proteins. Western blotting uses antibodies to detect proteins. Proteins are separated via gel electrophoresis, transferred to a membrane, and then probed with a primary antibody. Northern and Southern blotting use the same general idea, but with nucleic acids; nucleic acids are first separated on a gel, then transferred to a membrane, then probed with nucleic acids. Nucleic acids are not used to detect proteins and antibodies are not used to detect nucleic acids.

Damage to which chamber of the heart would be most evident in the measurement of systolic blood pressure by a standard sphygmomanometer?

Left ventricle A sphygmomanometer, or blood pressure cuff, measures systemic arterial pressure. Systolic blood pressure is measured during the contraction of the ventricles, and diastolic blood pressure is measured during relaxation. The left side of the heart is responsible for systemic circulation while the right side is responsible for pulmonic circulation, and specifically, the left ventricle provides the force for blood to be propelled from the heart into the systemic circulatory system. If this chamber were damaged and not providing the same amount of force, the difference would be seen in standard systolic blood pressure measurements. Changes to other chambers of the heart would not have as significant an impact.

What do ligaments do?

Ligaments link bone to bone

Which of the following represents the correct order of events?

Light stimulates rod cells, rod cells hyperpolarize and release the inhibition on biopolar cells, which stimulate ganglion cells, a signal is sent along the optic nerve.

Which of the following best describes the main site of ketogenesis?

Liver cell mitochondria

What role does the macula densa (in the distal tubule) play in regulating blood pressure?

Low filtrate osmolarity triggers the macula densa to stimulate the JG cells and dilate the afferent arterioles.

A bacterial strain auxotrophic for lysine, isoleucine, and alanine production is mixed with an Hfr bacterial strain whose genome needs to be mapped. A sample taken after three minutes is able to grow on media supplemented with isoleucine and alanine. A sample taken after six minutes is able to grow on media supplemented with only isoleucine. A sample taken after nine minutes is able to grow on minimal media. What is the order of the amino acid synthesis genes on the Hfr strain?

Lysine - Alanine - Isoleucine It can be assumed that the bacteria are conjugating. After three minutes, the resultant new strain is able to grow in the absence of leucine, indicating that the leucine synthesis gene was transferred first. After six minutes, it was able to grow in the absence of leucine and alanine (the alanine synthesis gene was transferred second), and after nine minutes the new bacterial strain needed no supplementation, indicating that the isoleucine synthesis gene was the final gene transferred.

Discuss MHC I vs. MHC II

MHC I is found on all nucleated cells, including antigen presenting cells. MHC I presents peptide fragments to cytotoxic T cells via the CD8 receptor. MHC II presents peptide fragments to helper T cells via the CD4 receptor. However, MHC II is found only on antigen presenting cells, such as macrophages and B cells.

Bacterial samples from two patients with necrotizing fasciitis are collected and grown in Petri dishes with minimal medium. The plates are labeled Plate A and Plate B, for Patient A and Patient B, respectively. The next day, a drop of penicillin is added to the center of each plate and the cultures are again incubated. Lawns and plaques were observed and it was determined that Patient A was infected with MRSA, and Patient B was infected with PenS Streptococcus pyogenes. Which of the following is correct about the cultures on the plates at the end of the experiment?

MRSA is resistant to penicillin, and therefore the growth of these bacteria will not be affected by the presence of this antibiotic. Therefore, Plate A will only have a lawn (an unbroken layer of bacteria on the surface of the growth medium) without a plaque (an area of clearing, or no bacterial growth, within a lawn); choices B and C can be eliminated. If Streptococcus pyogenes is PenS(as stated in the question stem), it is sensitive (not resistant) to penicillin. The bacteria on Plate B would have grown a lawn over the first night, then the cells that were contacted by the drop of penicillin would have died over the second night, producing a plaque (choice D can be eliminated and choice A is correct).

Viroids are circular pieces of single-stranded RNA, approximately 200-400 bases in length. What induces the folding of these subviral particles?

Many regions of self-complementarity

A decrease in blood pH can lead to a decrease in CSF pH, which can trigger an increase in ventilation rate. Which region of the brain contains the respiratory center that can alter the rate of ventilation?

Medulla oblongata

Which region of the brain contains the respiratory center that can alter the rate of ventilation?

Medulla oblongata

During which of the following are cells with a single unreplicated copy of the genome formed in humans?

Meiosis II In humans, the only cells that have a single copy of the genome are gametes, formed during meiosis. Cells have a single unreplicated copy of the genome after the second meiotic division.

Which types of protein are produced by the ribosomes of the rough endoplasmic reticulum?

Membrane-bound Integral Secreted

How are mitochondrial diseases inherited?

Mitochondrial diseases (diseases caused by alleles on the mitochondrial genome) are inherited via "maternal inheritance." This is due to the fact that only the egg (and not sperm) contributes mitochondria to the developing embryo.

Which of the following is an example of passive transport?

Movement of protons into the mitochondrial matrix in oxidative phosphorylation, with the proton influx driving ATP synthesis

Large proteins, most notably albumin, are dissolved in the plasma and serve an important role in regulation of plasma volume. Reducing the amount of albumin to below-normal levels would most likely have which of the following effects?

Movement of water from the bloodstream into the tissues with resulting swelling, due to reduced osmotic pressure The loss of protein from the plasma would cause the osmotic pressure of the blood to go down. It would not affect the hydrostatic pressure (blood pressure). The reduced osmotic pressure of the blood will have the effect of allowing water to leave the bloodstream and enter the tissues, where it will cause the tissues to swell.

The double helix contains several types of covalent bonds and is stabilized by many intermolecular forces. These include:

N-glycosidic linkage between deoxyribose and the nitrogenous base; van der Waals and hydrophobic interactions between bases.

the additive response due to repeated stimulation of a single neuron

Na+ leak channels

A third locus (Locus 3) is analyzed. If Locus 3 encodes a gene related to the number of offspring produced, and the population is homozygous at Locus 3, which of the following is true?

Natural selection can only operate if there is genetic diversity. If the entire population is homozygous at Locus 3, there is no diversity for natural selection to operate on

In which shock state might one observe low blood pressure and low heart rate?

Neurogenic - injury to sympathetic nervous system ---> vasodilation Cardiogenic and hypovolemic --> low blood pressure along with increase in heart rate

Anemia is characterized by a reduced oxygen-carrying capacity of the blood, most commonly due to a decrease in hemoglobin production or a reduction in red blood cell count. Would an individual who was mildly anemic due to iron deficiency experience an increase in resting ventilation rate?

No, anemia does not directly affect blood gas concentrations or blood pH.

Will cochlea implants be successful in a patient with a lesion in the cochlear nuclei?

No, hearing cannot be restored because normal functioning of the neuronal component is necessary

An experiment with a previously unidentified pathogen is done using guinea pigs and various means of inoculation are attempted. Within a few days, the guinea pigs begin to demonstrate a loss of coordination along with other neurological symptoms. Could the organism be a prion?

No; the onset of symptoms was too rapid Prion incubation times are long; in humans, it can take years or even decades. The onset as described in the question is too rapid, even in the small animal model of the guinea pig. Prions can infect all sorts of animals so guinea pigs are not specifically immune and loss of coordination can be a sign of all sorts of disorders and infections. There an many means by which prion infection can be acquired, including mutation.

Which of the following neurotransmitters is released by sympathetic neurons onto the heart?

Norepinephrine The sympathetic division of the ANS primarily releases norepinephrine (NE) at the organ level; the only significant exception is the sweat glands, where it releases acetylcholine ACh is the primary neurotransmitter of the parasympathetic division Epinephrine is a hormone; its release into the blood is triggered by the sympathetic nervous system and it can stimulate similar receptors as norepinephrine (choice C is wrong). Serotonin is a neurotransmitter used in the brain; it is not secreted by autonomic neurons (choice D is wrong).

Alternative splicing permits somatic cells to contain the same genome while maintaining the capability to express widely differing proteins, based on the tissue in which the cell is located. Which experimental techniques are useful in detecting the differing cellular products created by alternative splicing?

Northern Blotting Western Blotting ELISA Alternative splicing creates different mRNA sequences leading to different proteins, thus any technique that detects changes in mRNA transcripts or final protein products could be useful. Northern blotting is used to detect RNA and both Western blotting and ELISAs can be used to detect proteins. However, Southern blotting is used to detect DNA, and a point made by the question is that the genomes are the same (therefore the least useful technique).

Which of these proteins binds calcium in smooth muscle cells?

Of these proteins, calmodulin binds calcium in smooth muscle cells. Instead of using the troponin-tropomyosin complex to bind calcium and facilitate actin-myosin interaction (as seen in striated muscle), calcium ions bind to calmodulin. This in turn activates myosin light-chain kinase (MLCK) to phosphorylate the myosin and enable it to bind actin. Myosin and actin are found in all muscle types, though their arrangement differs in striated and smooth muscle.

Oogenesis is different from spermatogenesis in that:

Only one ootid is generated from one oogonium

A hypertonic solution creates a gradient that will draw fluid through a semi-permeable membrane. Which of the following is a true statement?

Osmotic pressure is the force necessary to counterbalance the pull on fluid exerted by the hypertonic solution

In a culture of mammalian skeletal muscle cells, the consumption of oxygen and glucose is measured. Which of the following would occur in response to inhibition of electron transport?

Oxygen consumption will decrease, and glucose consumption will increase In the absence of electron transport, oxygen is not needed (it is the final electron acceptor in the transport chain) so the consumption of oxygen would decrease. Since the electron transport chain is not available to make energy (ATP) the cells will rely solely on anaerobic respiration - glycolysis. Further, since the energy demands of the cells have not changed, and since glycolysis makes fewer ATP than electron transport, the rate of glycolysis will have to increase to keep the level of ATP normal. Thus, glucose consumption would increase.

A mutation in hemoglobin is identified that decreases the degree of cooperativity of binding of oxygen to nH = 1.4 (for normal hemoglobin, nH = 2.8). What is true of this mutant form of hemoglobin?

Oxygen release from hemoglobin will occur over a larger range of partial pressures of oxygen The greater the degree of cooperativity of hemoglobin, the more concerted the oxygen binding and release from hemoglobin.

What is pcr?

PCR amplification allows you to take a specific sequence of DNA and make multiple copies of it.

Describe the PCR cycles

PCR cycles through 3 temperatures: high temperature for template denaturing, low temperature for primer annealing and medium temperature for polymerization.

Regarding the pacemaker cells in the sinoatrial node:

Pacemaker cells are present in the SA node, the AV node, and the His-Purkinje tracts and exhibit automaticity, which is the result of an unstable resting potential. The instability is due to a steady influx of sodium ions across the membrane through sodium leak channels (not voltage-gated sodium channels). Once the membrane reaches the threshold potential, voltage-gated calcium channels open, allowing calcium to flow into the cells and the membrane to depolarize, and once the membrane become very positive (around +20 mV), voltage-gated potassium channels open and allow potassium ions to flow out of the cells and the membrane to repolarize.

Cochlear hair cells are most similar to which of the following types of receptors?

Pacinian corpuscles (pressure receptors in the skin) Golgi tendon organs (stretch receptors in tendons) the hair cells fire an action potential (nerve impulse) on bending, thus they would be classified as mechanoreceptors; mechanoreceptors fire when their shape changes in some way due to a mechanical disturbance.

Which of the following is found in meiosis but not mitosis?

Paired homologous chromosomes Separation of sister chromatids occurs during anaphase of mitosis and anaphase II of meiosis. However, only in meiosis do the homologous chromosomes pair up. This occurs during prophase I of meiosis.

What prevents pepsin from destroying the cells of the stomach that produce this hydrolytic enzyme?

Pepsin remains in an inactive state until it is cleaved by HCl.

What kind of hormones is prolactin?

Peptide Hormone

Following the binding of a loaded tRNA to its codon during translation, which of the following steps occurs next?

Peptide bond formation Following the binding of a loaded tRNA to a codon, the growing peptide chain is transferred from the tRNA occupying the P site to the tRNA occupying the A site via a peptidyl transfer reaction (i.e., a peptide bond is formed between the last amino acid in the chain and the new amino acid on the tRNA in the A site, choice C is correct).

Auditory transduction occurs inside the cochlea. How is the pitch of a sound determined?

Pitch is determined by the location of maximal vibration along the basilar membrane. High pitched (high frequency) sounds vibrate the stiffer region of the basilar membrane near the oval window, while low pitched (low frequency) sounds vibrate the more flexible apex of the basilar membrane

All of the following are well-recognized multicellular eukaryotic kingdoms:

Plantae, Animalia, Fungi (yeast is the only unicellular fungus)

What is pleiotropism?

Pleiotropism is the idea that alterations of a single gene result in changes in seemingly unrelated aspects of the organism's overall phenotype

Functions of cholesterol?

Precursor for steroid hormones Increase fluidity of plasma membranes Precursor for bile

What allows for a similarity in how cardiac muscle and smooth muscle transmit action potentials from cell to cell?

Presence of gap junctions

The Bcl-XL protein has an important role in programmed cell death. Which of the following could be the role of Bcl-XL?

Prevents the release of cytochrome c, thus negatively regulating apoptosis Since two answer choices say promoting apoptosis (or programmed cell death) and two say inhibiting apoptosis, this is a typical 2X2 question. The insertions in Bcl-XL in Figure 1 all go in the forward direction. This means Bcl-XL is a likely oncogene and is promoting tumor growth (see explanation to question 2). To do this, it must block apoptosis, not promote it (eliminate choices A and B). Cytochrome c is an important component of the electron transport chain. It would only be released from the mitochondria when the mitochondria is made permeable during apoptosis. Therefore apoptosis must involve the release of cytochrome c. To inhibit apoptosis, Bcl-XL protein must inhibit this release (choice C is correct, eliminate choice D)

Which of the following would be required to run a polymerase chain reaction (PCR)?

Primers Taq DNA polymerase Template DNA

What is the primary contribution of B cells in an adaptive immune response?

Production of antibodies specific to an antigen

What happens in a Western blot?

Proteins are probed with antibodies in a western blot

Which of the following statements regarding the separation of proteins via gel electrophoresis is correct?

Proteins with smaller molecular weights travel more quickly than those with higher molecular weights when an electric current is applied. Proteins travel in denatured states through the gel. Proteins migrate to the positive electrode of the gel apparatus because they become negatively charged during their preparation for electrophoresis. Decreasing the percent of polyacrylamide makes the gel less dense and increases the ability to resolve small distances between two proteins with similar molecular weights.

Irregular electrical activity is observed in one cardiac ventricle, but not the other. This defect in transmission is most likely found in which component of the cardiac conduction system?

Purkinje fibers The sinoatrial node supplies electrical signal to the atria and the atrioventricular node (via the intermodal pathway) and functions as the pacemaker of the heart. The internodal pathway carries impulses between the heart's two signaling nodes. A defect in the intermodal pathway or in either node would result in symmetrical changes to both ventricles. The right and left bundle branches bifurcate after the AV node and ramify to form the Purkinje fibers in the two ventricles, with each ventricle having its own separate set of Purkinje fibers.

Which of the following is the equation for recombination frequency (RF)?

RF = number of recombinant phenotypes / total number of progeny

Which of the following could be found in a bacterial cytoplasm, but NOT in an animal cell cytoplasm?

RNA polymerase

How is a standard curve formulated for a radioimmunoassay?

Radiolabeled antigen is mixed with antibody followed by antigen without the radiolabel and the decrease in radioactivity is measured as the amount of unlabeled antigen increases. Radioimmunoassays are a type of competition assay where the radiolabeled version is offset by the unlabeled version and the decrease in radioactivity indicates the level of the unknown being measured. This process is done with known concentrations of each to establish the standard curve to which results from unknowns can then be compared.

Evolution is the set of long-term changes in a population gene pool caused by selection pressures. Speciation is the evolutionary creation of new, genetically distinct populations from a common ancestral stock. Which of the following factors can contribute to the process of speciation?

Random mutation Geographic isolation Climate changes

Barr bodies are inactivated X chromosomes, more densely coiled than typical chromosomes. They are typically formed during embryonic development of females; one of the two X chromosomes becomes a Barr body and the other remains active. This prevents the overexpression of proteins coded for by the X chromosome. What is the fate of the Barr body during meiosis?

Reactivation occurs before prophase I

Which of the following transport mechanisms allow for infection of animal cells by viruses?

Receptor-mediated endocytosis Receptor-mediated endocytosis allows for infection of animal cells by viruses. Animal cells can take up viruses by endocytosis when the virus interacts with a specific cell surface receptor. Viruses, though small, are not small enough for simple diffusion. Facilitated diffusion also moves material smaller than viruses. Secondary active transport uses energy to establish electrochemical gradients, which can then be used to move material against its concentration gradient; concentration gradients are not a component of viral infections.

Which of the following involves the specific uptake of material into the cell?

Receptor-mediated endocytosis Receptor-mediated endocytosis uses clathrin-coated pits on the cell surface as the basis for endosomes in which to package material that binds to the receptor and bring it into the cell (choice B is correct). Phagocytosis and pinocytosis both involve non-specific uptake

How do chromosomal translocations end up potentially creating new gene products or enhancing the activity of existing gene products?

Recombination occurs between non-homologous chromosomes placing previously unconnected sequences in proximity.

If a circular spot is bleached in a cell membrane uniformly containing high levels of a fluorescent transmembrane protein, what best describes the change in fluorescence over time?

Recovery of fluorescence beginning at the periphery of the spot due to lateral diffusion of proteins in the membrane Photobleaching involves the permanent quenching of fluorescence. Given this is an integral membrane protein, it is capable of lateral diffusion within the cell membrane and non-bleached protein will begin to encroach on the bleached spot shortly after bleaching. Flipases are enzymes responsible for transferring lipids from one leaflet of the membrane to the other and would not be involved in protein translocation. Transmembrane proteins are translated at the endoplasmic reticulum and inserted into the membrane via a vesicle, thus newly translated proteins in the cytoplasm would not diffuse into the membrane and are not responsible for recovery in this instance. Bleaching does not result in the relaxation of excited electrons giving visible light and would not account for fluorescence recovery.

Which of the following meiotic characteristics does mitosis share?

Replication of chromosomes occurs prior to prophase

Tetrodotoxin (TTX) is a potent neurotoxin that binds to and inhibits the action of voltage-gated sodium channels in neurons. Poisoning can be rapidly fatal, within 4-6 hours of ingestion. Which of the following is the most likely cause of death from TTX poisoning?

Respiratory failure Blocking the action of voltage-gated sodium channels in neurons would prevent the occurrence of action potentials, leading to skeletal muscle paralysis. Because the diaphragm is made of skeletal muscle, it too would become paralyzed, leading to respiratory failure and death.

What is RFLP?

Restriction Fragment Length Polymorphism (RFLP) analysis is a means of distinguishing different strands of DNA

Northern blotting could be used to explore all of the following:

Retroviral genome Viroid Transcripts NOT bacterial genome Northern blotting could be used to explore all of the following EXCEPT bacterial genome. Northern blotting is used to probe RNA sequences. Retroviruses are a type of (+)sense single-stranded RNA viruses, viroids are sequences of RNA, and transcripts are composed of RNA. However, bacterial genomes are composed of DNA; Southern blotting would be a better choice.

Scientists hypothesize that certain types of lung disease are the result of fragments of plasmid DNA being inserted into an exon of mRNA, leading to defective proteins. If a scientist identified a cell line that contained the mutant mRNA and they wanted to determine the actual base sequence of the mutation, which of the following techniques would be most useful in generating a large amount of genetic material to use for sequencing?

Reverse Transcriptase Polymerase Chain Reaction (RT-PCR)

Which one of the following structures is found in bacterial cells?

Ribosome Ribosomes are assemblies of protein and RNA, not organelles, and although there are differences between prokaryotes and eukaryotes, both forms of life have ribosomes. Mitochondrion, endoplasmic reticulum, and nuclear membrane are wrong because bacteria are prokaryotes and therefore lack all subcellular membrane-bound organelles, including mitochondria, the ER, and the nucleus.

Where in the adult human is both mitosis and meiosis occurring in parallel?

Seminiferous tubules Meiosis is preceded by mitosis. Mitotic production of gametic cells is completed in the human female at the time of birth. However, adult males have a constant cycle of spermatogonia production (via mitosis) leading to meiosis in the seminiferous tubules. Thus both processes occur in that location.

paracrine signaling

Signal released from a cell has an effect on neighboring cells.

Unlike the blistering seen in porphyria cutanea tarda, deep burns can cause a multitude of other symptoms and complications. 3rd degree burns destroy the epidermis, underlying dermis, and possibly the underlying muscle tissue. A patient presents at the emergency room with severe, 3rd degree burns to his right arm, chest, and abdomen. Which of the following is LEAST likely to be a complication in this patient?

Significant pain in the burned area paradoxically, there is less pain with 3rd degree burns because of the destruction of the dermis and its associated nerves and pain receptors

Where is the pacemaker of the heart located?

Sino-atrial (SA) node

Where in the heart does its electrical signal originate?

Sinoatrial node

Which of the following is the best description of genomic organization at the start of mitosis?

Sister chromatids connected by a centromere

Sodium plays the principle role in rapid depolarization during action potentials due to which of the following?

Sodium conductance results in a positive membrane potential

Trace pathway of sound in ear.

Sound waves --> outer ear --> ear canal --> ear drum (vibrates) --> movement of 3 ossicles (malleus, incus, stapes) in middle ear --> oval window of cochlea which has fluid perilymph and tiny hair cells (in inner ear) --> movement of stapes on cochlea produces waves in perilymph --> movement of hair cells --> action potentials that are transmitted via the eighth cranial nerve to the brainstem

Which of the following lab techniques is described by the following steps? Step 1: Separate DNA fragments on a gel Step 2: Transfer fragments to a nitrocellulose filter Step 3: Probe the filter for the target DNA sequence with hybridized probes

Southern blotting The steps describe Southern blotting. Radioimmunoassay uses radioactively labeled antibodies to find target proteins or other target antibodies (radioimmunoassay is wrong). ELISA uses enzymatically labeled antibodies to find target proteins or other target antibodies (ELISA is wrong). Conjugation is a means by which bacteria can increase genetic diversity; it is not a lab technique (conjugation is wrong).

endocrine signaling

Specialized cells release hormone molecules into vessels of the circulatory system, by which they travel to target cells in other parts of the body.

Eukaryotic DNA is initially transcribed as hnRNA, then spliced to form mature mRNA. Which of the following is true of RNA splicing?

Splicing of hnRNA from a single gene can be variable

Polysaccharides can be used for many different functions. Which of the following is/are polysaccharides that are used primarily for glucose storage?

Starch Glycogen -starch is the polysaccharide used by plants to store glucose -glycogen is the polysaccharide that animals use to store glucose

How are steroid hormones stored in cells?

Steroid hormones are not stored; they are synthesized as needed

What does ACTH do?

Stimulates the adrenal cortex to produce cortisol and aldosterone

Which cells of the skin undergo mitosis in order to replace damaged squamous epithelial skin cells?

Stratum basale

What is the primary source of nutrition for the cartilage of the knee joint?

Synovial fluid

A man on a hunting trip sustains an accidental gunshot wound. The bullet penetrates the skull and travels a short way into the cerebral cortex. Shortly after the accident, the man finds that his sense of smell has been impaired. Which of the following brain regions was most likely damaged?

Temporal lobe

What is the Bohr Effect explain?

The Bohr Effect refers to the observation that increases in the carbon dioxide partial pressure of blood or decreases in blood pH result in a lower affinity of hemoglobin for oxygen.

During a polymerase chain reaction, high heat is used to denature and separate the DNA strands while cooling allows primers to anneal. Why does the extension step require additional heating?

The DNA polymerase used is heat sensitive and will not elongate in cooler conditions.

Chloroplasts and mitochondria have their own chromosomes. The genomes of chloroplasts and mitochondria must replicate during:

The G1 phase

Why does the fluid buildup caused by infectious pneumonia affect oxygen transport?

The additional fluid slows oxygen diffusion into the capillaries

What is temporal summation?

The additive response due to repeated stimulation of a single neuron

What does the adrenal cortex make?

The adrenal cortex makes primarily cortisol and aldosterone. Lack of aldosterone will reduce reabsorption of sodium and water from urine as it forms, increasing the volume of urine produced

This statement is true of antibodies.

The antigen-binding region is made of both heavy and light chains, but the tail region is made only of heavy chains

The binding free energy of DAPP intercalating with DNA can be divided into several components. Which of the following energy components is unfavorable?

The desolvation energy, or the free energy change of removing the electrostatic interactions between the ionic solvent and the ligand upon binding. The desolvation energy is unfavorable; the ligand in solution creates favorable electrostatic interactions with its environment by attracting counter-ions to balance its charge. These interactions have to be broken in order for the ligand to complex with DNA. This is why increasing the salt concentration of the solvent makes intercalation less favorable.

What are the effects of calcitrol?

The effects of calcitriol include a release of Ca2+ from the bones, reabsorption of Ca2+ by the kidney cells, and increased absorption of Ca2+ by the intestines.

It is known that the developing frog embryo requires greater protein production than the adult organism. If cells from a developing frog embryo and from a mature frog were examined, would the investigator find the greater rate of translation in cells of the embryo or of the adult?

The embryo, because a developing organism requires a higher rate of translation than does an adult.

Linking ATP hydrolysis to Na+ and K+ transport affects ion transport in which of the following ways?

The equilibrium and delta G for sodium and potassium transport are altered

A decrease in osmolarity in the peritubular capillaries would have what effect on the filtrate in the nephron?

The filtrate would remain less concentrated and retain more water.

The pentose phosphate pathway (PPP) generates NADPH to be used as a reducing agent in biosynthetic reactions such as fatty acid synthesis, and generates ribulose-5-phosphate which can either be converted into ribose-5-phosphate or into glycolytic intermediates. Ribose-5-phosphate can also be generated from glycolytic intermediates without the reduction of NADPH. Which of the following would be favored in a rapidly dividing cell?

The formation of ribose-5-phosphate Cells that are rapidly dividing need to synthesize nucleic acids, thus the formation of ribose-5-phosphate, a precursor to nucleotides, would be favored (choice A is correct). NADPH is not necessary for nucleotide synthesis so the oxidative phase of the PPP would not be favored (choice B is wrong). The conversion of ribulose-5-P into glycolytic intermediates would shuttle the five-carbon sugar back into glycolysis when it would be more needed as a nucleotide precursor (choice C is wrong). NADH is not generated in the pentose phosphate pathway (choice D is wrong).

The following is true of the bacteria living in the large intestine

The gastrointestinal tract has a limited supply of oxygen within it, especially once the large intestine is reached. Bacteria residing there must be facultative or obligate anaerobes. The bacteria compete with pathogens, providing an additional immune mechanism and also produce vitamin K, which is involved in blood clotting. The fact that both humans and bacteria benefit from this arrangement makes this a mutualistic relationship.

What is erythropoietin (EPO)?

The hormone that stimulates the production of red blood cells

During puberty and sexual maturation, what impact do androgens and estrogens have on the epiphyseal plate?

The hormones ossify the epiphyseal plate, thus stopping growth.

Animal viruses that reproduce via the productive cycle are sometimes said to be more evolutionarily advanced than those that perform the lytic cycle. Which of the following gives a reason for this?

The host cell can survive the productive cycle because the virus exits the cell by budding. The virus particles are released when the host cell bursts in the lytic cycle, but escape by budding out of the host cell in the productive cycle

The exchange of fluid between the blood in the capillaries and the surrounding tissues is the result of opposing osmotic and hydrostatic pressure differentials. Which of the following accurately describes the relationship between hydrostatic and osmotic pressure differentials in the capillaries?

The hydrostatic pressure differential causes fluid to move out of the capillaries at the arterial end. Arterial pressure is higher than the pressure on the venous side of the capillaries. Thus, hydrostatic pressure tends to drive fluids out of the blood and into the tissues on the arterial side and back out of the tissues on the venous side. Osmotic pressure is greater in the plasma than in the interstitial fluid, because plasma has a much higher protein concentration; therefore, osmotic pressure tends to draw fluid into the blood, out of the tissues.

A patient being treated with antibiotics for a severe bacterial infection appears to worsen when treatment begins, experiencing decreases in blood pressure. As treatment progresses, the infection resolves and the patient's blood pressure returns to normal. Why did the patient's condition degrade when starting treatment?

The infection was likely caused by a Gram-negative bacterium producing endotoxins. Gram-negative bacteria produce endotoxins as part of their outer lipid bilayer and these are released upon cell death. Treating an infection with such a bacterium can cause a worsening of symptoms, including issues with blood pressure, until the endotoxin begins to break down. Exotoxins are released continuously by bacteria and would not be specifically impacted by treatment with an antibiotic. While certain strains of bacteria do "cap snatch" by removing the 5' caps from host cell transcripts, this would not explain the patient's clinical progress. If C. difficile established itself in the gut due to the elimination of flora by the antibiotic, more severe symptoms would be expected rather than resolution of the condition.

What are the functions of the liver?

The liver has a number of functions in the body, including synthesis of bile, glycogen storage and metabolism, synthesis of blood proteins (such as albumin, fibrinogen, angiotensinogen, lipoproteins, etc., amino acid metabolism, production of urea, vitamin storage, detoxification, etc

If a color blind man without hemophilia marries a woman who is a carrier for both traits, what is the probability they would have a son affected by both color blindness and hemophilia? Assume that the hemophilia and color blindness genes are unlinked.

The man's genotype is XcY and the woman's genotype is XcX/XhX. Note that the question states that they hemophilia and color blindness genes are effectively unlinked, meaning that in the woman they are either on different X chromosomes or they are far enough apart on the same X chromosome that they can be considered unlinked. The Rule of Multiplication states that the probability of two (or more) independent events occurring together is the product of their individual probabilities. In this case, we want three things to happen: the man must donate the Y chromosome (a 1/2 probability), the woman must donate Xh (a 1/2 probability), and she must also donate Xc (a 1/2 probability). The probability of all three things occurring together is 1/2 x 1/2 x 1/2, or 1/8.

Hair cells used to detect motion are found in which of the following structures?

The organ of Corti (inner ear) The semicircular canals Both the organ of Corti and the semicircular canals contain hair cells with small "hairs" that project from the apical surface of the cell into the surrounding fluid. Movement of the fluid around the hair cells detects sound in the organ of Corti and a change in body orientation in the semicircular canals. Item II is incorrect: Hair in the skin is different; it is not made up of "hair cells" but is made up of dead epithelial cells.

Which phase of the pentose phosphate pathway would a rapidly dividing cell be expected to utilize most?

The oxidative phase because it generates pentose rings.

The introduction of a new predator onto the island resulted in the death of all tall birds, but short birds were not affected. The birds were killed by the predator in youth, soon after hatching. After two generations of birds, the predator population died off on the island, and no new predators arrived. Which of the following will occur after the death of the predators, assuming Hardy-Weinberg equilibrium?

The percentage of tall birds and short birds will remain constant one generation after the death of the predator. The Hardy-Weinberg theory states that allele frequencies will be unchanging if certain conditions are met. The question text says to assume Hardy-Weinberg equilibrium, therefore the allele frequencies should not change. Note that it takes one generation to establish a Hardy-Weinberg equilibrium.

Which of the following explains why incompatible fetal blood type does not induce an immune response in a pregnant female, but a HIV-positive woman can pass the disease on to her new baby?

The placenta is a complex capillary network that allows many maternal blood components to pass into fetal circulation, but only waste products to pass into maternal circulation

Polydactyly (extra fingers or toes) is a congenital physical anomaly that can be caused by recessive or dominant alleles. It is found more frequently in blacks than in whites, and more frequently in men than in women. A study on autosomal dominant polydactyly in men showed that the frequency of the allele causing polydactyly in this population was 2%? What is the frequency of affected individuals in this population?

The question states that in this population, polydactyly is caused by a dominant allele. In the Hardy Weinberg equation for allele frequency (p + q = 1), p is the frequency of the dominant allele. If p = 0.02, then q = 0.98. Plugging these numbers into the equation for genotype frequency (p2 + 2pq+ q2 = 1), q2 (the frequency of autosomal recessive individuals, and thus UNaffected individuals) is equal to (0.98)2 = 0.96; or in other words, 96% of the population is NOT affected. Therefore, 4% of the population IS affected.

Temporal summation relies upon which of the following?

The rate of excitation must be more rapid than the recovery rate. Temporal summation results from the repeated stimulation of a single postsynaptic neuron.

What is the function of the temporal lobe?

The region of the brain that processes olfactory sensation (smell) is the temporal lobe as well as hearing. - smell - hearing

What bonds/interactions are responsible for maintaining quaternary structure of a protein?

The same bonds/interactions responsible for the tertiary structure

If an electrophoretic gel is placed in reverse, but the DNA samples are still loaded into the established wells, what will happen to the sample?

The samples will run out of the back of the gel towards the positive electrode rather than down the length of the gel toward the negative electrode. Electrophoresis uses electrical current to separate based on size and weight, not density. Since DNA is negatively charged, it will still be trying to move away from the negative electrode and towards the positive electrode, thus it will end up running towards the back of the gel and off of it. DNA cannot run towards the negative electrode at all since it is also negatively charged.

A scientist takes 10 μL of culture containing E. coli cells and puts them in a tube with 4 fmol of a plasmid. The tube is placed on ice for half an hour, then resuspended while in a 42°C water bath for 10 seconds. The bacteria are plated on selective media and grown overnight at 37°C. Which of the following is true?

The scientist performed transformation and is selecting for plasmid-containing bacteria by using agar plates coated with an antibiotic. Selective media is used for the growth of selected microorganisms. It can contain an antibiotic which will select for any cell that expresses a resistance gene to this antibiotic

Given a frequency of 2.3 kHz and considering the speed of sound in air is 340 m/s, what is the wavelength of the sound wave in air?

The speed of a sound wave is related to the frequency and wavelength of the wave by the equation: v = fλ, where v is the speed of sound, f is the frequency of sound and λ is the wavelength of the wave. The wavelength therefore is given by the equation: λ = v/f = (3.4 x 102)/(2.3 x 103) = 1.5 x 10-1m. Thus the best answer is 0.150 meters or 15 centimeters (choice B is correct). Choice A comes from incorrectly converting 0.150 meters to centimeters (choice A is incorrect). Choices C and D result from dividing frequency by the wave speed (choices C and D are wrong).

How does the speed of a sound wave in the cochlea compare to its speed in the outer ear?

The speed will increase because the fluid in the cochlea is incompressible compared to air

Two populations of a tree species were separated by a river that prevented interbreeding. During a period of stable climate, one population lost the ability to reproduce sexually. Many generations later, the climate became much more arid and the river was no longer present. Which of the following is most likely to occur?

The two populations will each form a species evolving independently The two key parts of this question are (1) the two populations were separated by a river that prevented interbreeding (the populations were physically isolated), and (2) one of the populations lost the ability to breed sexually, meaning that it could no longer mate with the other population (the populations were reproductively isolated). The loss of sexual reproduction is not likely to revert (choice A is wrong), and mutation will occur in any population; it is not driven by the ability to reproduce sexually (choice B is wrong). The sexually-reproducing population will evolve more rapidly than the asexual population because sexual reproduction involves mixing up the genetic information and it creates a greater variation in offspring (choice D is wrong). This is a classic set-up for speciation, and the two populations represent the definition for separate species - an inability to interbreed. Because the two populations are no longer able to mate, they will evolve independently of one another.

Which of the following is/are true about the relationship between heart contractions and the autonomic nervous system?

The vagus nerve releases acetylcholine and slows the heart rate. The heart is capable of contracting in the complete absence of nervous system input.

During ventricular contraction, which of the following valves is open?

The valve between the left ventricle and the aorta

Which of the following would be true of the Lineweaver-Burk plot for a non-competitive inhibitor?

The y-intercept of the graph would be bigger, and the x-intercept would not change.

A zymogen of a caspase protein is present within the cytosol of a cell. Which of the following is true?

The zymogen must be cleaved in a certain way before the caspase protein is produced

Which of the following is true regarding the human genome?

There are 46 total chromosomes with 22 pairs of autosomes, 1 pair of sex chromosomes, one locus per gene, 4 RNA bases, 64 codons and 1 amino acid per codon

If a trihybrid (heterozygous for three genes) round worm is crossed to a worm that is AaBBcc, which of the following is true of the F1 offspring?

There are four possible phenotypes in the offspring. The cross in the question stem is AaBbCc × AaBBcc. For the first locus, three genotypes will be possible (25% AA, 50% Aa and 25% aa) but only two phenotypes: 75% dominant A and 25% recessive a (choice A is false and can be eliminated). The worms will be 50% BB and 50% Bb at the second locus (choice B is false and can be eliminated) but will all express the dominant B phenotype. For the third locus, the worms will be 50% Cc and 50% cc, and the phenotypic ratios will be the same (choice C is false and can be eliminated). Therefore, the answer must be D; there are two possible phenotypes at the first locus, one possible phenotype at the second locus, and two possible phenotypes at the third locus. (2)(1)(2) = 4 possible phenotypes.

Which of the following is LEAST likely to occur in an individual with uncontrolled diabetes?

There is an increase in the amount of glucose-6-phosphate, which is shunted toward the pentose phosphate pathway. Uncontrolled diabetes results in hyperglycemia, due to either a relative or complete deficiency of insulin. This means the glucose in the blood cannot be transported into the cells. Thus, any processes that are dependent on glucose oxidation will be decreased and other processes to generate energy will be increased. Fatty acid oxidation would be increased, as the cells would break down fatty acids to produce acetyl-CoA to feed into the Krebs cycle. This would result in an increase in acetyl-CoA, not a decrease. Since glycolysis is decreased, there would be a decrease in glucose-6-phosphate that is available for the pentose phosphate pathway (not an increase) and thus, a decrease in the amount of NADPH produced by the pentose phosphate pathway.

Which of the following is generally true regarding the provirus state of HIV?

There is no viral genome transcription or translation; only passive replication of the genome occurs.

Eukaryotic flagella

They are cytoplasmic extensions with a 9+2 arrangement of microtubules

Which of the following statements is/are true of linked genes?

They are found close together on the same piece of DNA.

What best characterizes alveolar ducts, which follow the respiratory bronchioles?

They are thin-walled branches of the respiratory zone where gas exchange can occur.

Coronaviruses are enveloped, +RNA viruses that typically cause respiratory infections. A coronavirus was implicated in the SARS epidemic of 2002. Which of the following statements are true about Coronavirus?

They can be cultured in animal cells. Their genome likely has a poly-A tail. The items "they can be cultured only in eukaryotic cells" and "their genome likely has a poly-A tail" are true about Coronavirus. Item I is false: because the viruses are enveloped, they can only grow in animal cells. Item II is true: The envelope of the virus is derived from the plasma membrane of the host cell as the virus buds out; since all other cells have a cell wall, budding through the cell membrane/wall of those cells is not possible. Note also that additional unique enzymes do not have to be introduced with the virus; since it is +RNA it can be immediately translated into whatever unique enzyme might be needed. Item III is true: since the viral host is eukaryotic, and since it has an RNA genome, it is likely that the genome has a poly-A tail to mimic eukaryotic RNA and facilitate translation.

What will happen if adrenal glands are removed?

They make cortisol in the absence of ACTH from the pituitary - Thus, cortisol levels will fall rapidly and ACTH will increase due to the lack of feedback inhibition by cortisol in the plasma

What is the relationship between PTH and calcitriol?

They work together to increase serum calcium

What is spatial summation?

This additive effect (two neurons synapsing on a single neuron and generating a larger response)

LEARN THIS*** In a given population of a single species of fish in a large fishbowl, the color of their scales is determined by an autosomal gene. Yellow is the recessive color and red is the dominant color. If, out of a total of 800 fish, 288 of the fish are yellow, what is the frequency of the recessive "yellow" allele in the population?

This is a Hardy-Weinberg population genetics question. Recall the equation: p2 + 2pq + q2 = 1, where p represents the frequency of the dominant allele, q the recessive allele, p2 the homozygous dominant genotype, 2pq the heterozygous genotype, and q2 the homozygous recessive genotype. Since yellow is a recessive allele, only homozygous recessive fish will be yellow. The question states that there are 288 yellow fish. Thus, the frequency of yellow fish is 288/800 = 0.36 (36%). Since 0.36 represents the frequency of the homozygous recessive genotype, q2 = 0.36. It follows that q = 0.6 (60%), which represents the frequency of the recessive allele in the population.

What is the likely effect of insulin?

To modify activity of cytoplasmic proteins necessary for uptake and utilization of glucose Insulin is a peptide hormone

Which of the following accurately describes the structure of a bacterium?

Transcription and translation can occur simultaneously, as both occur in the cytoplasm and no post-transcriptional modification is required. The bacterial genome is a circular, double-stranded DNA molecule. While many peptide chains can be made from a polycistronic mRNA, this is done by a 70S ribosome in bacteria. The eukaryotic ribosome is 80S. The peptidoglycan cell wall prevents lysis due to osmotic pressure, but doesn't generate osmotic pressure gradients. Many eukaryotic cells have aquaporin water channels in the plasma membrane to facilitate osmosis.

During the absorption of dietary fat, the molecule is broken down before being reassembled following absorption. What is dietary fat broken down into before absorption?

Two fatty acids and one monoglyceride

How might one explain the differences between IDDM (type 1 - insulin dependent diabetes mellitus) and NIDDM (type 2)?

Type I diabetes is caused by antibodies to the β cell while type II is caused by antibodies to the insulin receptor. In IDDM, the β cells are destroyed, so no insulin is present. In NIDDM, insulin is made but does not have the effects it should.

Which of the following is specific to an animal virus and NOT to a bacteriophage?

Un-coating of a genome from the capsid coat within the host cell cytoplasm

How does light stimulate rods and cones?

Upon absorption of a photon, cis bonds in retinal are converted to trans bonds, which alter the potential of photoreceptors in rods and cones

Which of the following describes the route via which urine leaves the kidney and is voided from the body?

Ureter, bladder, involuntary urinary sphincter, voluntary urinary sphincter

What cellular process can viroids exploit in order to replicate their genomes?

Use of transcriptional machinery Viroids can alter the RNA polymerase and transcriptional machinery of certain host cells to replicate their genetic material. Primase makes a short RNA sequence from a DNA template, ribosomes synthesize amino acids into proteins and DNA polymerase copies DNA from DNA so none of these would work to produce RNA in any form.

Which of the following describes a mechanism by which a viroid can cause disease?

Viroids can serve as siRNAs that silence expression of genes that are necessary for cell function. Viroids are small fragments of RNA, and do not have capsids. While viroids are RNA, they do not cause disease by causing proteins to misfold.

Which channel is responsible for the plateau in the cardiac action potential?

Voltage-gated Ca2+

The nephrons of the kidney are responsible for filtering blood and modifying the filtrate to produce urine. Which of the following provides the best description of the initial composition of filtrate in a healthy individual?

Water, glucose, ions (hydrophilic)

What is selectively reabsorbed by the proximal convoluted tubule?

Water, ions, glucose, amino acids

What are western blots?

Western blots use antibodies to detect specific proteins in a given sample of tissue extract.

Which of the following represents a postzygotic barrier to hybridization/speciation?

When a horse mates with a donkey, a mule is born and the mule is sterile

Which of the following is a true statement about bacterial conjugation?

While conjugation increases the number of male and Hfr cells, binary fission can increase the number of female cells.

Would an individual without a parathyroid gland be expected to have difficulty breathing?

Yes, because decreased calcium induces convulsions and tetany

a bipolar neuron could be composed of which of the following?

a neuron with a soma, a single dendrite, and a single axon

What is the site of ACTH action?

adrenal gland

Which one of the following is a function of the ossicles in the middle ear?

amplify the transmission of the sound vibrations

In fermentation processes, the final acceptor of electrons from NADH is:

an organic compound

A researcher cuts a thin slice of a fixed tissue, mounts it on a microscope slide and permeabilizes the cells. She can then:

analyze the tissue by in situ hybridization, to determine where a transcript is found in the cell. analyze the tissue by immunohistochemistry to determine where a protein is found in the cell.

Klinefelter's syndrome, in which a male has an extra X chromosome (XXY), is the result of nondisjunction. The failure in spermatogenesis that could produce this would occur in:

anaphase I for a sperm to cause the defect, it must contain both an X and a Y chromosome. X and Y would count as "homologous chromosomes" and so would normally separate during meiosis I. Failure to do so could create a sperm containing both an X and a Y which could cause Klinefelter's syndrome. The separation occurs during anaphase, when chromosomes are drawn away from each other toward opposite sides of the two cells being formed. Thus, the answer is anaphase I.

A motor unit is the group of skeletal muscle cells innervated by a single motor neuron. The muscle cells of a motor unit:

are multinucleate and do not share cytoplasmic contents with each other.

Before a gene targeted mouse embryonic stem cell line can be used to generate a transgenic animal, chromosome quantification is performed to ensure the cell line has the appropriate number of chromosomes. To do this, cells are grown in the presence of colcemid for four hours, cells are then harvested and nuclear clusters are collected and stained. Colcemid treatment most likely:

arrests the cells in metaphase Chromosomes are condensed by metaphase, so arresting cells in this mitotic phase would be ideal.

The primary mechanism of shivering thermogenesis is:

asynchronous contraction of muscle fibers

What happens to B cells that recognize soluble self-antigens?

become anergic or inactivated

During T cell maturation in the thymus, immature T-cells that bind to normal proteins should:

become apoptotic

The middle layer of the eyeball has:

blood vessels

Map distances can be calculated by:

calculating recombination frequencies. Recombination frequency gives a measure of map distances between genes on the same chromosome

Connective tissue functions to bind and support other tissues. Which of the following is/are example(s) of connective tissue?

cartilage and bone

What is the somatic motor system controlled by?

cerebral cortex

Nerve impulses from hair cells traveling to the brain get processed finally in the:

cerebral gray matter (cerebral cortex) - processes "higher" information than white matter

When running an ELISA to test for the presence of anti-chickenpox antibody in a patient's blood, which of the following would be bound to the microtiter well plate?

chickenpox antigen When testing for the presence of antibody in a patient's blood, the antigen for which that antibody is specific must be bound to the microtiter well plate. Primary antibody is only bound to the well plate when testing for the presence of antigen in a patient's blood. Neither secondary antibody (the one conjugated to an enzyme) nor the enzyme itself can ever be bound to the well plate or false-positive results would occur.

All of the following are components or types of loose connective tissue

collagen, adipose tissue, the extracellular matrix

The renal medulla is made up primarily of:

collecting ducts

What is the first sign of mitosis?

condensing of chromosomes - during prophase

What do nerve plexi do in the tunica muscularis?

control GI motility

What happens when light strikes the cornea? Trace the path.

cornea --> anterior chamber --> lens --> vitreous chamber --> retina

The function of the loop of Henle is to:

create a concentration gradient in the medulla to facilitate the reabsorption of water at the collecting duct.

Hearing loss is restricted to a particular frequency range.

damage to a group of hair cells

During alcoholic fermentation, the molecules pyruvic acid and acetaldehyde are, respectively:

decarboxylated and reduced

Autophagy in lysosomes is responsible for:

degrading nonfunctional cellular components. Autophagy refers to the process by which the cell degrades worn out cellular components

What are epithelial cells in the skin connected by?

desmosomes

UV light can trigger the formation of pyrimidine dimers, which then cause malformed loops of DNA. Visible light can then trigger repair enzymes via photoreactivation. This describes a DNA repair mechanism known as:

direct reversal

A man's back is touched with two needles at the same time, close together, with equal pressure. He feels only one poke. This is due to:

distribution of touch receptors both needles poke the domain of a single receptor

What do Helper T cells do?

do not lyse infected cells directly. Instead, they secrete cytokines to enhance cytotoxic T cell and B cell proliferation

The cell bodies of a somatic sensory nerve are located in the:

dorsal root ganglion - just behind and along the length of the spinal cord

The controlled balance between bone formation and resorption is regulated by at least three hormones, parathyroid hormone, calcitonin, and calcitriol, which respond to changes in serum Ca2+ levels. Paget's disease is caused by a high rate of bone resorption, which exceeds the rate of bone formation regardless of serum Ca2+ levels. A potential treatment for Paget's disease could be:

drugs that mimic the effect of calcitonin

What is ELISA?

enzyme-linked immunosorbent assay ELISA uses fluorescent or enzyme-linked antibodies to find either antigen or other antibodies in a person's serum

Some mammals have unusually long loops of Henle that maintain steep osmotic gradients. This allows for the organism to:

excrete urine that is more hypertonic

In the liver, insulin normally acts to promote:

fatty acid synthesis

What is the function of the parietal lobe?

for general sensations of pain, pressure, and touch

A small subpopulation of beetles with a slightly advantageous modification of pincer structure was found to be wiped out after a locally isolated severe wind storm. A biologist studying this event would most likely attribute the loss of the advantageous gene as due to:

genetic drift

The polyuria in diabetes mellitus is caused most directly by which of the diseases other manifestations?

glycosuria

What does acetylcholine do?

has inhibitory effects on cardiac pacemaker activity

Helper T-cells can be distinguished from cytotoxic T-cells in that:

helper T cells recognize antigen complexed with MHC II. cytotoxic T cells recognize antigen complexed with MHC I.

Glucose exists predominantly as a:

hexose, aldose and pyranose

What is glycosuria?

high urinary glucose concentration - draws excess water into the renal tubules by osmosis

Addison's disease, or chronic adrenal insufficiency, is due to hypofunction of the adrenal cortex. This condition will make a person have:

high urinary output

In the condition myopia the inverted image formed by the lens falls:

in front of the retina

Spermatogenesis occurs:

in the seminiferous tubules, starting near the basement membrane and finishing near the lumen

A deficiency of vitamin D is most likely to:

increase PTH secretion.

One would expect cardiac output to increase the most with:

increased levels of anti-diuretic hormone and inhibition of vagus nerve

High levels of ATP would:

inhibit phosphofructokinase and inhibit pyruvate kinase, thus inhibiting glycolysis.

What is insulin stimulated by?

insulin is stimulated by high glucose to increase glucose uptake

MHC II polypeptides enter the rough ER lumen by:

interacting with a signal recognition particle and a signal recognition particle receptor on the ER surface

The ability to taste phenylthiocarbamide depends on genetics. Humans with the dominant allele taste phenylthiocarbamide as very bitter and make up about 70% of the population. The allele that leads to phenylthiocarbamide being tasteless:

is recessive and occurs at a frequency of 0.55. Since the ability to taste phenylthiocarbamide is dominant we will assign it an allele frequency of p. From the equation for genotype frequency (p2 + 2pq + q2 = 1), individuals who have this trait will make up p2 + 2pq of the population, which the question states is 70%, or 0.70. The recessive allele leads to tasteless phenylthiocarbamide (choices B and D can be eliminated) and occurs at a frequency of q, so individuals who cannot taste phenylthiocarbamide occur at a frequency of q2. Since the question stem tells you p2 + 2pq = 0.70, q2 = 1 - 0.70 = 0.30, and q would be the square root of this number, or approximately 0.55 (choice A is correct and choice C is wrong).

A block in prophase II of spermatogenesis would result in:

limited numbers of spermatids.

What do φ-ψ peptidyl linkages link?

link amino acids in protein -Note that φ and ψ correspond to bond angles present around the alpha carbon in a protein.

Females with Turner's syndrome have a high incidence of hemophilia, a recessive X-linked trait. Based on this statement, it can be inferred that females with this syndrome have:

lost an X A recessive trait will only be expressed if it is present in both copies or is the only copy of the gene present. A recessive X-linked allele would only be expressed in normal women who have two copies of the allele. If only one X is present, however, then all recessive alleles on the X, such as hemophilia, will be expressed.

What is DNA fingerprinting?

method by which scientists can distinguish different DNA samples but does NOT generate a large amount of DNA

Herbivores have longer alimentary canals than carnivores relative to their body size. This evolutionary process occurred because it allows:

microorganisms to feed off the nutrients

Why does chemotherapy for cancer cause diarrhea and malnutrition?

mucosal cells divide very frequency

The substance in control of G1 arrest:

must be present in the cytoplasm

There are many hallmarks of cancer, including sustained proliferative signaling, replicative immortality, resistance to cell death, genome instability and induction of angiogenesis. These are fundamentally due to:

mutations and other genomic changes which could cause increased oncoprotein function, loss of tumor suppressor function, but also other changes such as production of oncometabolites

The evolution of chameleon color change is driven by the ability to produce social signaling to potential mates. This is an example of:

non-random mating Since selection for the ability to change colors is driven by social cues rather than the ability to camouflage, it is not natural selection (choice A is wrong). Migration is irrelevant (choice D is wrong). Although the ability to change color might be caused by genetic mutations, it is selected for because of non-random mating, making choice C better than choice B.

What is another word for an allosteric inhibitor?

noncompetitive

What is the function of the occipital lobe?

occipital lobe processes visual sensation - visual (sight)

What are racemic mixtures?

optically inactive

What is p53?

p53 is a tumor suppressor gene

What can cause incontinence?

peripheral neuropathy

What happens to platelets when there is damaged tissue?

platelets bind to exposed collagen in damaged tissue to trigger clotting

By shutting off their apoptotic machinery, cancer cells are most likely:

protecting themselves from the suicide process that their abnormal behavior would otherwise activate.

What does gyrase do?

reduce supercoiling compacts bacterial genomes

The cell cycle (mitosis and interphase) can involve all of the following genetic events:

replication. transcription. translation.

The ratio of guanine-cytosine (G—C) pairs to adenine-thymine (A—T) pairs is useful in laboratory manipulation of double-stranded DNA. If a segment of DNA has a low G—C : A—T ratio, it would be reasonable to assume that this segment would:

require less energy to separate the two DNA strands than would a comparable segment of DNA having a high G—C : A—T ratio

What is vitamin A?

retinal is a Vitamin A derivative Vitamin A is a fat soluble vitamin

What prevents unspliced mRNA coding for MHC Class I proteins from being translated in the nucleus?

ribosomes are excluded from the interior of the nucleus

The brain contributes to sex hormone secretion in males by:

secreting LH (which affects interstitial cells in the testes) and FSH (which stimulates sustentacular cells)

M6P marker

sends things to lysosome

In what kind of muscle has T-tubules?

skeletal muscle

What occurs in the absence of insulin signaling?

stimulation of ketone body production by liver

Cortisol

stress hormone released by the adrenal cortex

What is edema?

swelling

Just memorize

sympathetic --(releases)--> norepinephrine --> pupil dilation parasympathetic --> acetylcholine --> pupil constriction

Skeletal muscle is attached to bone by:

tendons.

A patient with a large hump on the back, red stripes on the abdomen and elevated laboratory cortisol levels would lead you to first suspect:

that the patient is taking corticosteroids prescribed by another doctor

In males:

the Wolffian duct develops into male internal genitalia, and spermatogonia regenerate via mitosis throughout adult life

What is the autonomic motor system controlled by?

the brain stem

The ER lumen is most closely like what?

the extracellular environment

What is the location of focal point in astigmatism?

the focal points may be located in front of, behind or in the same plane as the retina

A virologist is working to classify a new pathogen, and believes that it is a viroid. If the new pathogen is a viroid, an analysis of the pathogen should show that:

the genome contains no thymine Viroids are RNA, and thus, there would be no thymine in its genome. Viroids do not have capsids and do not usually code for proteins. Viroids are single stranded; the ratio of A to G nucleotides is not 1:1.

A benefit of the lysogenic viral cycle is that:

the host remains alive and the viral genome is replicated with every round of cell division.

assortive mating

the mating of phenotypically similar organisms

What is oncotic pressure?

the osmotic pressure exerted by proteins in blood plasma.

During fertilization:

the sperm must penetrate both the corona radiata and the vitelline layer

What does the vagus nerve do?

the vagus nerve is a parasympathetic nerve; it uses acetylcholine as its neurotransmitter and reduces the heart rate

Carbon dioxide is a small, hydrophobic molecule that diffuses through cell membranes. Its movement can be described as:

thermodynamically favorable because it increases entropy.

What do corticosteroids do?

they cause systemic immunosuppression

role of albumin

to keep blood and fluid in the vessel

In the dermis of mammals, "nets" of nerve fibers surround the bases of hairs. These fibers most likely aid in the detection of:

touch (movement)

In normal cells, Bax is a cytosolic protein. Upon initiation of apoptosis, Bax undergoes a conformational shift, associates with the inner mitochondrial membrane and induces the opening of the mitochondrial voltage-dependent anion channel, VDAC. Animal models lacking Bax would most likely display:

tumor formation (because Bax is a TSG) but with slower kinetics than p53 knockout mice.

What are yeasts?

unicellular

How do macrophages display antigen?

using class II MHC

The primary function of fructose and buffers in semen is to help spermatozoa survive the path from the:

vas deferens to the fallopian tube, by providing nutrients and pH regulation. Spermatids are made in the seminiferous tubules of the testes, mature in the epididymis and are stored as spermatozoa in the vas deferens until ejaculation.

Lymphatic vessels are most like:

veins, because they carry fluid toward the heart and are at low pressure

What is non-random mating?

when individuals select mates based on proximity or phenotype

The hypothalamus modulates pituitary activity by producing releasing and inhibiting factors. Disruption of the hypothalamic-pituitary portal system would most likely result in:

widespread endocrine malfunction

The rate of oxidative metabolism is measured using a basal metabolic rate (BMR) test. If a subject has hyperthyroidism, the rate:

will be above normal Patients with hyperthyroidism produce excess amounts of thyroid hormone, thus increasing their BMR. One of the primary activities of thyroid hormone is to increase the basal metabolic rate.

What is the equation for ΔGº?

ΔGº = - RT (ln Keq)

Which compounds are components of the citric acid cycle?

α-Ketoglutarate Succinate Malate

What best explains the reason for the inability of the human intestinal tract to digest cellulose?

β(1,4) linkages

Which of the following occurs during starvation?

β-oxidation in the mitochondrial matrix provides acetyl-CoA to feed into the Krebs cycle.

What are the primary functions of the liver?

-Bile production and excretion -Excretion of bilirubin, cholesterol, hormones, and drugs -Metabolism of fats, proteins, and carbohydrates -Enzyme activation -Storage of glycogen, vitamins, minerals - Maintains blood glucose -Synthesis of plasma proteins such as albumin and clotting factors -Blood detoxification and purification

Antimycin is used as a piscicide (fish poison) because it inhibits Complex III of the electron transport chain. Blocking the flow of electrons through Complex III will produce which of the following effects?

-Complex I (NADH dehydrogenase) will persist in a reduced state -Oxygen consumption will be decreased Reduced electron carriers like NADH and FADH2 transport electrons from the reactions of glycolysis, the pyruvate dehydrogenase complex, and the Krebs cycle to the electron transport chain. Electrons are then relayed through the various proteins of the chain and finally to oxygen, which is reduced to water. Inhibiting any part of the electron transport chain will halt the transfer of electrons. Item I is true: Blocking electron transport at Complex III will result in a build-up of electrons at proteins earlier in the chain. Because these earlier proteins, including Complex I, cannot pass their electrons off, they will persist in the reduced state ("Gain of Electrons is a Reduction"). Item II, however, is false: Proteins later in the chain can release their electrons, but cannot replenish them. These later proteins, including Complex IV, will persist in the oxidized state ("Loss of Electrons is an Oxidation"). Electrons meeting a roadblock at Complex III will never reach oxygen. Item III is true: Thus, oxygen consumption (reduction) will be decreased. It is important to note that inhibiting the electron transport chain diminishes the proton gradient and compromises ATP synthesis. This is why antimycin is so toxic to cells.

Which statements regarding enzymes are true?

-Enzymes speed up reactions by lowering the energy of activation -Enzymes are not used up during reactions -Enzymes do not affect the thermodynamics of a reaction -Enzymes decrease the kinetic barrier

Which of the following statements is/are true regarding melanin?

-It is located in the epidermis (basal layer) -It protects against DNA damage inflicted by UV rays. -Its production can be triggered by signal transduction initiated by p53.

ADH (antidiuretic hormone, also called vasopressin) causes increased water retention by the kidneys, allowing a more concentrated urine to be produced. Which of the following is/are true about ADH?

-It is released when blood pressure is low. -ADH is actually made in the hypothalamus, then transported to the posterior pituitary, where it is stored until release -the release of ADH is triggered by an action potential, not a releasing hormone (RH). Only the anterior pituitary hormones are controlled by releasing hormones

Which of the following is/are a function of the lymphatic system

-Recover excess tissue fluid and return it to the circulatory system -Absorb and transport fats from the intestines (lacteals) -Filter fluid to remove antigens and other potentially harmful substances

What organs perform endocrine functions?

-Thyroid, Testes, Pancreas -The pancreas (secretes insulin and glucagon), testes (secrete testosterone), and thyroid (secretes thyroxine) are all endocrine glands.

All of the following could help prevent cancer:

-activation of initiator caspases upon cellular oxidative damage -p53 activation in response to accelerated progression through the cell cycle

All of the following statements regarding antibody structure are true:

-antibodies have a quaternary protein structure -genes for antibodies undergo genetic rearrangement to ensure that a very wide variety of antigen-binding regions can be produced -antibodies can neutralize certain toxins

ELISA test

-detects anti-(HIV) antibodies; Western blot given as follow-up -enzyme-linked immunosorbent assay

In the United States, approximately 1 in 30 Ashkenazi Jews is a carrier of the gene for Tay-Sachs disease, a devastating autosomal recessive disorder, which in its severe forms leads to death prior to five years of age. If two unaffected Ashkenazi Jews randomly met and mated, what is the probability of having a child affected with Tay Sachs disease?

1 out of 3600 In order to inherit an autosomal recessive disease, the child would have to inherit a diseased allele from each of their parents; therefore, both parents would have to be carriers for the disease. The question stem states that the parents are unaffected, so they cannot be homozygous for the mutated allele, and besides, homozygotes die before age 5. The question states that the prevalence of the recessive allele is 1/30. Use the rule of multiplication to determine the answer. This rule states that the probability of the mother being a carrier (1/30) AND passing on the affected allele (1/2) AND the father being a carrier (1/30) AND passing on the affected allele (1/2) is equal to the product of the probabilities of each event occurring: 1/30 × 1/30 × 1/2 × 1/2 = 1/3600. Thus, there is a 1 out of 3600 chance that two unaffected Ashkenazi Jews would have child with Tay-Sachs disease

β-Oxidation is a means of creating acetyl-CoA from fatty acids. This acetyl-CoA can then enter the Krebs cycle. Each turn of the β-oxidation cycle produces one acetyl-CoA molecule and a fatty acid two carbons shorter than it was at the beginning of the cycle. Additionally, one NADH and one FADH2 are generated per turn. Lauric acid is an 12-carbon saturated fatty acid. Including those produced in the Krebs cycle, how many total NADH and FADH2 molecules would be generated from the complete β-oxidation of lauric acid and subsequent entry of the acetyl-CoA into the Krebs cycle?

23 NADH and 11 FADH2 Each turn of the β-oxidation cycle produces one acetyl-CoA and a fatty acid two carbons shorter than before. Lauric acid, with 12 carbons, would ultimately produce 6 acetyl-CoA. If lauric acid enters the β-oxidation cycle, then after one turn of the cycle we would have one acetyl-CoA and a 10C fatty acid. After two turns of the cycle we would have two acetyl-CoA and an 8C fatty acid. This would continue in this manner until after the 5th turn of the cycle we would produce our 5th acetyl-CoA molecule, and all that would be left over would be another two-carbon acetyl-CoA molecule (the 6thacetyl-CoA). This last 2-carbon molecule does not need to go through the β-oxidation cycle again, so only 5 turns of cycle are necessary. Thus, 5 NADH and 5 FADH2 would be generated during β-oxidation. When the 6 acetyl-CoA molecules go through the Krebs cycle, and additional 18 NADH would be generate (3 per turn of the Krebs cycle) and and additional 6 FADH2 would be generated (1 per turn), for a total of 23 NADH and 11 FADH2.

Some amino acids can be converted to pyruvate via several biochemical pathways. Pyruvate can then enter the cellular respiration pathways, either by decarboxylation to acetyl-CoA or by carboxylation to oxaloacetate. For a single pyruvate molecule, first converted to acetyl-CoA, then traveling through the Krebs cycle, how many NADH molecules are produced?

4 The decarboxylation of pyruvate to acetyl-CoA nets 1 NADH, and as that acetyl-CoA travels through the Krebs cycle, an additional 3 NADH are generated, resulting in a total of 4 NADH per pyruvate

During the metabolism of a fatty acid side chain containing 11 carbons, how many water molecules are used and how much FADH2 is produced?

4 molecules of water, 4 FADH2 4 molecules of water will be used and 4 FADH2 will be produced during the oxidation of an 11-C fatty acid. Fatty acid metabolism occurs by removal of two carbons per round of β-oxidation until the final two or three carbons are reached, depending on whether the original fatty acid chain had an even or odd number of carbons in total. Since the side chain in the question has a total of 11 carbons, there will be four rounds of β-oxidation, leaving the final three carbons at the end of the process. Each β-oxidation uses one water molecule and produces one FADH2 (as well as one NADH although the question does not ask about NADH).

Color blindness is a recessive trait passed on through a sex-linked gene on the X chromosome. If a woman who carries the allele for color blindness has a child with a man who is color blind, what is the probability that a female offspring will be a carrier?

50% Female children will receive one X from their father and one X from their mother. The X from the father must carry the color blindness allele since the father is color blind. The X from the mother has a 50/50 chance of being either normal or carrying the color blindness allele since she is heterozygous recessive. Thus, 50% of female children will be homozygous color blind, and 50% will be heterozygous carriers of the color blindness trait.

A geneticist discovers two genes in the zebrafish genome that are 42 cM apart. A homozygous dominant fish is crossed with a homozygous recessive fish, and one of the F1offspring is testcrossed. Which of the following is true of the F2 fish?

58% have phenotypes like the parental fish. Let's assign the two parental fish AABB × aabb. The F1fish would be AB/ab (in linkage notation) and is mated with a ab/ab fish in a testcross. If the two genes are linked and 42 cM (centimorgans, a measure of distance on the chromosome) apart, 42% of offspring would result from crossing over in the heterozygous parent (generating aB or Ab gametes, choices C and D are wrong) and the remaining 58% would have parental combinations of alleles (AB or ab). In other words, we would expect 29% AB/ab and 29% ab/ab(the parental combinations totaling 58%; choice B is correct and choice A is wrong), and 21% Ab/ab and 21% aB/ab(recombinant combinations totaling 42%).

The ABO typing of red blood cells is determined by antigens expressed on the surface of the cell, which are coded for by three different alleles: IA, IA, IB and i. If the frequency of the IA gene is 0.1, the IB gene is 0.05 and the i gene is 0.85, what percent of the population would have type B blood?

8.75 The genotype causing blood type B can be either IB IB or IB i. Since there are 3 alleles, and humans are diploid, the formula (from Equation 1) becomes (p1 + p2 + p3)2 = 1, where p1 is the frequency of IA (0.01), p2 is the frequency of IB (0.05) and p3 is the frequency of i (0.85). For simplicity, let's say that p1 = p, p2 = q and p3 = r, then the equation becomes (p + q + r)2 = 1. Expanding this equation, it becomes: p2 + q2 + r2 + 2pq + 2pr + 2qr = 1, where the frequency for IB IB is q2 and the frequency for IB i is 2qr. Solving for the frequency of the type B blood type, we get q2 + 2qr = (0.05)2 + 2(0.05)(0.85) = 0.0875, or 8.75 percent (choice D).

Nearsighted individuals are unable to focus on distant objects due to the image produced by the lens being focused in front of the retina. Given this, which type of lenses are necessary to correct this error?

A concave lens causing the light to diverge slightly before entering the eye

calmodulin

A cyoplasmic Ca2+-binding protein. Calmodulin is particularly important in smooth muscle cells, where binding of Ca2+ allows calmodulin to activate myosin light-chian kinase, the first step in smooth muscle cell contraction.

How would an increase in amplitude and decrease in the energy of a wave affect the fluctuation of the tympanic membrane, respectively?

A decrease in the frequency of oscillation and an increase in the distance moved.

Huntington's disease is due to CAG repeats in the HTT gene. An individual with 26 or fewer CAG repeats will not develop the disease and will not pass the trait onto any offspring. A patient with 27-35 repeats will not be affected but has a small chance of passing the trait onto their offspring due to further repeat expansion. An individual with 36-39 repeats in one copy of HTT may or may not develop Huntington's disease but has a 50% chance of passing this trait onto offspring. A patient with 40 or more CAG repeats in one copy of HTTwill develop the disease and has a 50% chance of passing it onto their children. Which of the following is true?

A patient with 40 or more CAG repeats in one copy of HTT has a 50% chance of passing Huntington's disease onto their children. This individual is heterozygous; since the offspring have a ½ chance of being affected, Huntington's disease must display autosomal dominant inheritance. A patient with 37 repeats may or may not develop the disease, which is a type of partial penetrance (another reason to eliminate choice C).

A biochemist assesses the changes in reaction rate of an enzyme-catalyzed reaction in a solution containing saturating quantities of a known inhibitor. When substrate is added, the reaction rate increases, but fails to reach the published Vmax for this enzyme concentration, even at concentrations of substrate well above that of the inhibitor. Interestingly, the researcher notes that the concentration of substrate required to reach half of the observed maximal rate matches the published value. What is true of this enzyme and its inhibitor?

Addition of inhibitor does not impact enzyme affinity for the substrate. The stem of the question describes a situation where an enzyme is in the presence of a saturating quantity of inhibitor and substrate is added. Given we have a decreased Vmax with an unchanged Km, this is likely a noncompetitive inhibitor. Km, or the concentration of substrate needed to reach half Vmax, is also a measure of enzyme affinity for the substrate and has not changed here. Vmax is impacted by enzyme concentration; more enzyme means an increased rate of product formation (although this is not being tested here) and inhibitor concentration does impact reaction rate (hence why they are inhibitors). For noncompetitive inhibition, the inhibitor binds to an allosteric site, not the active site. Binding to the active site indicates competitive inhibition, and this would be indicated by the reaction rate reaching Vmax at higher substrate concentrations (which does not happen in this case).

Which of the following would facilitate a DNA backbone parallel to that of a standard double helix?

Adenine and thymine This question is asking you (in a confusing sort of way) to find a purine-pyrimidine pair, since this is how nucleotides must pair across the double helix to ensure the backbone is parallel. Item I is true: adenine is a purine and thymine is a pyrimidine, thus will form a typical DNA double helix.

The cell signaling master regulator Akt binds phosphatidylinositol (4,5)-bisphosphate (PIP2) only when it is phosphorylated to form phosphatidylinositol (3,4,5)-trisphosphate (PIP3). This occurs via a pleckstrin homology (PH) domain, which is about 120 amino acids in length. Akt itself is then phosphorylated on amino acids 308 and 473, which allows it to positively regulate cellular survival and metabolism. Which of the following is most supported by the information above?

Akt is capable of binding phospholipids very specifically.

The effects of aldosterone on sudoriferous (sweat) glands of the skin are analogous to this hormone's effects on nephrons within the kidney. Which of the following is correct regarding how aldosterone influences the salt content of sweat?

Aldosterone decreases the secretion of sodium, making sweat more dilute. Aldosterone increases renal sodium reabsorption, returning more sodium to the blood. In the skin, this hormone also acts to conserve sodium by decreasing this ion's secretion.

Methoxy arachidonyl fluorophosphates (MAFPs) covalently link to the active sites of serine proteases. What best characterizes the activity of a serine protease following MAFP binding?

Binding of an MAFP to the serine protease active site results in negligible protease activity. Here, a serine protease is treated with an MAFP that covalently binds to the active site. This would result in an irreversible loss of protease activity and no amount of substrate could displace the covalently linked MAFP (competition is not possible when the inhibitor binds covalently). Irreversible inhibitors are those that act on a specific enzyme and prevent its further activity, often by covalently binding to it. As MAFP is not a peptide, it is very unlikely that a serine protease would cause its cleavage.

Which of the following observations would best explain the convulsions induced by hypocalcemia?

Decreased plasma calcium levels increase neuronal membrane permeability to sodium

Coarctation of the aorta, a congenital defect in which the aorta is narrowed, would cause which of the following if left untreated?

Decreased pressure in the lower limbs Since the aorta is the first vessel to receive fully pressurized blood in the systemic circuit, if it was narrowed, blood flow (and thus pressure) would be reduced to the rest of the body. The narrowed vessel would have an increased resistance, backing up blood and increasing pressures prior to that vessel (such as the pulmonic circuit)

Which of the following best characterizes the difference between the soma and axon hillock?

Decreased voltage-gated sodium channel density in the soma

Severe hemorrhage can greatly reduce the volume of extracellular fluids and reduce the blood pressure to the point of circulatory shock. Which of the following will occur immediately after severe hemorrhage?

Decreased volume of urinary output

Which of the following would lengthen Okazaki fragments?

Decreasing the number of primers generated on the lagging strand during replication This would result in DNA polymerase III traveling uninterrupted for a longer period of time and generating longer Okazaki fragments.

Stimulation of parasympathetic division

Increased digestive and stomach motility constricted bronchial tubes reduced heart rate

A graduate student attaches a fluorescent tag to β-galactosidase and performs site-directed mutagenesis to generate a mutation in the operator of the lac operon. The mutation completely prevents repressor binding. Which of the following is the most likely observation following mutagenesis of these cells?

Increased fluorescence compared to control due to failed repressor binding, in the presence or absence of lactose If the mutation prevents the repressor from binding to the operator, this would result in constitutive expression of the genes in the lac operon, including the fluorescent β-galactosidase. This would occur whether or not lactose was present.

An elderly patient presents with chronic renal failure and metabolic acidosis. What impact would this have on oxygen delivery to tissues?

Increased oxygen delivery due to hemoglobin's decreased oxygen affinity

Which of the following metabolic conditions would be expected to slow down the rate of glycolysis?

Increased ratio of ATP/AMP

A patient suffering from hypoglycemia is treated with new glucocorticoid that selectively promotes gluconeogenesis for a prolonged period of time. Which of the following best characterizes the patient after treatment?

Increased serum glucose and decreased glycolytic activity

Which of the following occurs in response to low blood pressure?

Increased water retention due to ADH release from the pituitary gland Systemic vasoconstriction

Which of the following will change the ∆G° of an enzyme catalyzed reaction?

Increasing temperature

Diabetics and alcoholics are especially susceptible to infection by Vibrio vulnificus, which can also lead to necrotizing fasciitis. When plated, it was found that this bacterium was able to survive on a plate with glucose, but not on a plate without glucose. What is most likely true about this bacterium?

It is a chemoheterotroph and a tolerant anaerobe. The question states that the bacteria did not survive in a glucose-free environment, thus they are unable to synthesize their own food and cannot be autotrophic (choices A and C can be eliminated). Since necrotic (dead/dying) tissue is usually almost void of oxygen, the bacteria should be able to survive without oxygen, making choice B a better answer than choice D.

A graduate student in a yeast lab that studies double-strand break (DSB) repair has a mutant strain that is unable to complete repair via nonhomologous end joining. Which of the following is true about this strain?

It is able to form a joint molecule when repairing DSBs. This mutant strain is unable to complete nonhomologous end joining and is thus relying on homologous recombination for DSB. This is a specific repair process (choice A is wrong) that involves formation of a joint molecule (choice B is correct) and uses DNA polymerase (choice D is wrong). A strain that repairs DNA via homologous end joining will be able to repair DSBs reasonably well, and will not accumulate many chromosomal aberrations over time (choice C is wrong).

In the Adams family, a father has blood type B+ and his wife has blood type A+. In the Wong family, a mother has blood type B- and her husband has blood type A+. All of the following are true EXCEPT:

It is impossible for any Adams or Wong family grandparents to have blood type O. If the Adams family parents are pure-breeding (or homozygous), then choice A is true and can be eliminated. All offspring would be IAIBRR and these individuals are called universal acceptors because they can accept all blood types without complications. If the Wong family parents are heterozygous for the ABO blood group (IAi × IBi), and if the Wong husband is heterozygous for the Rh antigen (Rr), then both choices B and D are possible and both can be eliminated (note that the Wong mother must be homozygous recessive for the Rh antigen as she is Rh negative). Some of the children could be blood type O- (iirr) which are universal donors and a blood type different from either parent. In each family, some grandparents could be blood type O (choice C is not true and is the correct answer choice). For example, IBRr (type B+) and iirr (type O-) grandparents could give rise to the Wong family mother.

What is true about cortisol?

It is released from the adrenal cortex in a stress situation and modifies transcription to exert its effect

Aplastic anemia is a condition where bone marrow is significantly damaged and does not produce sufficient new cells to replenish blood cells (e.g., in radiation poisoning). Which of the following is true with regard to aplastic anemia?

It primarily affects the red marrow in the spongy bone of flat bones

Which of the following is involved in both innate (non-specific) and specific immunity?

Macrophages Macrophages can act as non-specific phagocytes as well as specific phagocytes for antibody-coated antigen. Memory cells and MHC I are involved only in specific immunity, and lysozyme is involved in non-specific defense only (non-specific antibacterial enzyme)

Methicillin-resistant Staphylococcus aureus (MRSA) has become a serious cause of skin infections both in the community and in the hospital. S. aureus are Gram-positive cocci that typically grow in clusters in culture. Which of the following is true?

Methicillin functions to inhibit the transpeptidase enzyme used by bacteria to cross-link the peptides in the cell wall.

If tumor suppressor activity was induced exogenously to exceed normal levels by several-fold, which cellular process would most likely be blocked?

Mitosis Tumor suppressor genes work to prevent deregulated cell growth and division. Turning up their activity level would therefore most likely impact mitosis. Meiosis only occurs in gonads and both transcription and translation are not the focus of the monitoring by these gene products.

What components are required to traffic secretory proteins to the lumen of the endoplasmic reticulum?

N-terminal signal sequence, signal recognition particle

An exercise physiologist performs an in vitro assay to analyze the Bohr effect in a system where the bicarbonate in the blood has been replaced by a synthetic buffer. Following the addition of acetazolamide (a carbonic anhydrase inhibitor), he increased the partial pressure of carbon dioxide in this model system two-fold. Which of the following changes would be expected immediately?

No significant shift in the oxygen saturation curve The normal buffer of blood, bicarbonate, has been removed and carbonic anhydrase, which facilitates the reaction of carbon dioxide and water to form carbonic acid, has been inhibited. This results in blood pH being independent of carbon dioxide concentration and no significant shift in the hemoglobin saturation curve would take place. If the pH of the synthetic blood was changed, we would still observe the expected shifts in thehemoglobin/oxygen saturation curve as no changes in hemoglobin made.

There are many structural similarities and differences between eukaryotic and prokaryotic cells. Which of the following cellular structures are the same whether isolated from a prokaryote or eukaryote?

Plasma membrane Eukaryotic flagella are constructed out of microtubules in a "9 + 2" arrangement, whereas prokaryotic flagella are built out of a bacterial protein called flagellin (you don't need to know this name for the MCAT) and are organized in to a base, hook, and filament. Prokaryotic cell walls are constructed out of peptidoglycan, whereas eukaryotes with a cell wall utilize other carbohydrates, such as cellulose in plants or chitin in fungi. Prokaryotes have smaller 70S ribosomes (the "S" refers to the sedimentation rate during centrifugation), whereas eukaryotes have 80S ribosomes. However, the plasma membranes of eukaryotic and prokaryotic cells are organized similarly. They are phospholipid bilayers with other assorted structures (e.g., proteins, carbohydrates, etc.) embedded or attached.

Since proto-oncogenes have the ability to become cancerous, why are they maintained as part of the genome?

Proto-oncogenes often encode gene products, like growth factors, that are necessary for the cell when expressed at normal levels.

Which of the following is the best description of fibrous cartilage?

Provides rigid, strong support

Which of the following blood vessels carries blood with the highest PCO2?

Pulmonary artery The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs, so it carries the blood with the highest amount of carbon dioxide. The pulmonary vein carries oxygen-rich, CO2-poor blood from the lungs to the left atrium (pulmonary vein is wrong), the aorta carries this same oxygen-rich, CO2-poor blood to the body (aorta is wrong), and the renal artery carries oxygen-rich, CO2-poor blood to the kidneys (renal artery is wrong).

Even when no pathogens are present, alveoli are protected from infection by which of the following?

Specialized immune cells that reside within alveoli Alveolar macrophages are the specialized immune cells that patrol the alveoli for foreign microbes

These patients often experience progressive aortic dilation, particularly through the ascending aorta and the aortic arch. Such dilation would be expected to have which of the following effects?

The aortic semilunar valve would be expected to leak as the expansion of the aorta pulled on it resulting in changes to the second heart sound. Note that first heart sound is linked to the closure of the atrioventricular valves (tricuspid and mitral).

A physiologist observes a dark, dense subcellular structure via electron microscopy that spans the space between two adjacent cell membranes and extends to the underlying cytoskeleton. Upon further investigation, she discovers that two cells with this structure are electrically isolated but that a tracer dye can travel between the cells through the pericellular space. What is the identity of this structure?

The dark structure spanning the cell membranes is a desmosome. Desmosomes are a type of anchoring junction which connect adjacent cells and extend through the cell membrane to associate with components of the cytoskeleton. Unlike gap junctions (also known as communicating junctions), desmosomes do not link the cytoplasms of the two cells (the cells are not electrically coupled). Tight junctions form connections with adjacent cells but prevent pericellular diffusion of molecules, including that of a tracer dye.

A pure-breeding cactus with long spines and fuzz (SSFF) is crossed with a pure-breeding cactus with short spines and a smooth surface (no fuzz, ssff). Two of the F1s are crossed with each other to create an F2 generation. In the F2 cactus population, 27 cacti have long spines and fuzz, 10 cacti have long spines and a smooth surface, 8 cacti have short spines and fuzz, and 3 cacti have short spines and a smooth surface.Are the genes for spine length and cactus surface linked, and if so, how far apart are they on the chromosome?

The genes for spine length and cactus surface are not linked because the ratio of F2 cacti phenotypes matches the expected ratio for unlinked genes for this cross. All F1s from the original cross of the pure-breeding cacti will be dihybrids: heterozygous for both genes (SsFf). The expected unlinked ratio for a dihybrid cross (F1 x F1) is 9:3:3:1, and the ratio of 27:10:8:3 is pretty close to that. The fact that there are cacti with a mix of the original parental phenotypes is not significant; in order to determine linkage it is the ratio of these mixed phenotypes that is important.

Which of the following is a difference between eukaryotic and prokaryotic translation?

The mechanism by which ribosomes recognize the 5' end of mRNA Prokaryotic mRNA is recognized by the ribosome using the Shine-Dalgarno sequence (-10) while eukaryotic mRNA is recognized via the 5' cap that is added during post-transcriptional modification.

A woman who is considering having children is a carrier for Androgen Insensitivity Syndrome (AIS), an X-linked recessive disorder that results in the inability of cells to respond to androgens, such as testosterone. If this woman has a child with a man who does not have AIS, what is the probability that she will have a child with AIS?

The probability that she will have a child with AIS is 1/4. Since the woman is a carrier for Androgen Insensitivity Syndrome (AIS), her genotype is XAX, where XA is the allele that carries AIS. The man does not have AIS, so his genotype must be XY. Since the father's X chromosome is normal, any female born to the couple would have a normal phenotype (although half would be carriers). However, half of the males would inherit XA from their mother and Y from their father, giving them AIS. Since the question does not specify a sex, all four possibilities for children (XAX, XX, XAY, XY) must be considered. This means that the probability that they will have a child with AIS is 1/4.

A woman heterozygous for the gene that causes Ehlers Danlos syndrome, an autosomal dominant connective tissue disease, marries a man who is heterozygous for the gene causing familial hypercholesterolemia. Familial hypercholesterolemia is also an autosomal dominant disease. What is the probability that the couple will have a child who has both Ehlers Danlos syndrome and familial hypercholesterolemia?

The probability that the couple will have a child who has both Ehlers Danlos syndrome and familial hypercholesterolemia is 1/4. The woman's genotype is Eeff, since she has Ehlers Danlos syndrome, but does not have familial hypercholesteremia. The man's genotype is eeFf, since he does not have Ehlers Danlos syndrome, but does have familial hypercholesteremia. The probability, then, that a child will inherit Ehlers Danlos syndrome is 1/2. The probability that a child will inherit familial hypercholesterolemia is also 1/2. Using the rule of multiplication, the probability that a child will inherit both diseases is 1/2 x 1/2, or 1/4.

An atrial septal defect (ASD) allows oxygenated blood to flow from the left atrium into the right atrium through a hole in the heart wall. Surgical repair of pronounced ASD would help to prevent:

additional stress on the pulmonary circuit from increased pressure The presence of an ASD always means that oxygenated blood is mixing with deoxygenated blood and being returned unnecessarily to the lung; effectively the right and left sides of the heart are connected, so the higher pressure of the left side of the heart is translated to the pulmonary circuit.

Shapes, patterns, and movement are perceived by the retina and a complex network of pattern-recognition circuits in the brain. Colors, however, are identified:

by the relative stimulation of cones in the retina, of which there are only three types with regard to color perception Cones transduce color for the brain, while rods respond to black and white images. There are only three types of cones, and they are specific for different wavelengths of light. There is no selective filtering of light in the retina.

What is the function of the frontal lobe?

frontal lobe controls voluntary movement and problem solving prefrontal cortex, motor cortex, Broca's area

The sodium-potassium ATPase moves three sodium ions out of the cell and two potassium ions into the cell at the cost of one ATP molecule. In the absence of ion leak channels, the ATPase would make the cytoplasm:

hypotonic to the extracellular environment. Since the ATPase moves more ions out of the cell than in, and since in the absence of leak channels these ions have no way to cross the cell membrane, the cytoplasm would ultimately become hypotonic, meaning it has less particles when compared to the extracellular environment (choice C is correct). Hypertonic (or hyperosmotic) would mean that the cytoplasm had more particles than the extracellular environment (choices A and D are wrong), and isotonic would mean they had the same number of particles (choice B is wrong).

A researcher is making a transgenic mouse using gene targeted embryonic stem cells from a male black mouse, and a donor wild type morula from a brown mouse. This means that germline transmission of the targeted gene will most likely come from a:

male chimeric mouse with mostly black fur. The gene targeted mouse embryonic stem cells are from a male mouse with black fur. If these cells contribute significantly to the chimeric mice, the pups should also have black fur and be male. The most promising chimera is therefore a male with black fur. Brown mice developed mostly from the donor morula and will not contain the targeted gene. Similarly, female mice must have also developed from the donor morula and are not promising for germline transmission.

n Kartagener's syndrome, defective dynein is produced causing a paralysis of microtubule-based movement of flagellae and cilia. One could expect to find all of the following outcomes:

male infertility chronic lung infections ectopic pregnancy in women A male with Kartagener's syndrome would be infertile due to immobile sperm, eliminating male infertility. In females, ova would not enter the Fallopian tubes normally, due to the lack of cilia, causing increased risk of ectopic pregnancy, eliminating ectopic pregnancy in women. The lungs also require cilia to remove bacteria and other particulates, eliminating chronic lung infections. Ovulation, however, is determined by levels of circulating hormones and will not be affected by the lack of dynein.

Both microarrays and flow cytometry involve labeling biological agents with fluorescent markers. These two techniques are different in that:

microarrays give information on transcript levels, while flow cytometry gives information on which fluorescent molecules are bound to individual cells. Microarrays are a way to determine transcript levels that are being expressed by a population of cells. RNA is harvested from the cells, fluorescently labeled and applied to a chip. Microarrays are not used to determine directly which proteins are expressed by a cell. Flow cytometry looks at individual cells, as they are passed in a liquid stream through a laser. It does not look at cells in the context of a tissue.

A researcher is tracking two traits in a family. One trait is consistently passed from affected mothers to all offspring. The other trait passes from affected fathers to 0% of sons but 100% of daughters. The respective two traits are mostly likely:

mitochondrial and X-linked dominant X-linked recessive traits can be masked by a mother's dominant X chromosome in female offspring. If the trait is showing up in all of their daughters, it is most likely an X-linked dominant trait

What do we know about a low power light microscope?

not powerful enough to see bacteria or viruses

Antibody light chains are

not specific for each class of antibody Antibody light chains are not specific for each class of antibody. First, do not get confused between the variable region and the light chain. Remember that the light chain and the heavy chain have both variable and constant domains. Further, it is the heavy chain constant domain that is specific for each class of antibody; the light chain has no class specificity. The variable domains of the chains are specific for (and bind to) antigen, not the light chain as a whole. Antibodies are protein molecules, not carbohydrates.

What do 5'-3' phosphodiester bonds link?

nucleotides in DNA and RNA

An increase in which of the following increases the O2 affinity of hemoglobin?

pH The O2 dissociation curve is shifted to the right (reduced O2 affinity) by an increase in any of the following: H+ concentration (decreased pH), partial pressure of CO2, temperature, and the concentration of 2,3-BPG. An easier way to remember this is to think of the conditions in an exercising muscle (which would benefit from a reduced O2 affinity that allows for easier oxygen unloading): hot, acidic, and hypercarbic (increased CO2). Therefore, the opposite conditions would lead to an increased oxygen affinity, i.e. a decrease in H+ concentration (increased pH), partial pressure of CO2, temperature and the concentration of 2,3-BPG.

What is acetylcholine released by?

parasympathetic nervous system

What is Bradford quantification?

performed using a Bradford reagent and a UV-Vis spectrophotometer; it allows researchers to quantify the concentration of protein in a lysate mixture. In other words, it is performed on a solution of proteins

An infant born with a congenital defect in the ventricular septum that causes a mixing of blood between the right and left ventricles is most likely to suffer from:

poor tissue oxygenation. increased blood pressure in the pulmonary circuit. Item I is true: If blood between the left and right ventricles is mixed, then some deoxygenated blood from the right ventricle will mix with oxygenated blood from the left ventricle and be returned to the body. This blood, with its lower-than-normal level of oxygenation, will result in poorer tissue oxygenation. Item II is true: The left ventricle generates higher pressures than the right ventricle. If the two ventricles are essentially connected via a defect in the septum, the higher pressures from the left ventricle will translate to the right ventricle and into the pulmonary circuit.

Which of the following does NOT carry oxygenated blood?

pulmonary artery The pulmonary artery does NOT carry oxygenated blood. The pulmonary artery carries deoxygenated blood from the right ventricle to the lung to pick up oxygen. The femoral artery carries oxygenated blood in the leg, the coronary arteries branch from the aorta to provide oxygenated blood to the heart muscle cells, and the carotid arteries carry oxygenated blood from the aorta to the brain.

In cellular respiration, what acts as the final electron acceptor if oxygen is not available?

pyruvate

A patient presents at a hospital emergency room with a blockage in his left primary bronchus that completely obstructs air flow at that point. Compared to the curve for his right lung, the hemoglobin saturation curve for his left lung would be:

right-shifted, due to a decrease in pH

A hormone is discovered that rapidly accumulates inside renal cells in the absence of endocytosis when administered to mice intravenously. The hormone is most likely a:

steroid If the hormone accumulates inside the cell in the absence of endocytosis, the hormone must diffuse through the plasma membrane. Steroid hormones are small and hydrophobic and can freely diffuse through the plasma membrane

What is a diuretic?

substance that causes kidneys to remove water from blood, makes you urinate

If a single Na+/K+ ATPase were inserted into an artificial membrane, impermeable to all ions, with high conc. of ATP, Na and K on both sides of the membrane, what would result?

substantial ATP hydrolysis on only one side of the membrane, with accumulation of sodium on the opposite side

Due to electron transport in a eukaryotic cell:

the pH in the matrix of the mitochondria is higher because protons are pumped across the inner membrane of the mitochondria

What are the primary hormones of the adrenal cortex?

the primary hormones of the adrenal cortex include cortisol, aldosterone, and sex steroids

Cortisol exerts its negative feedback via:

the superior hypophyseal artery

autocrine signaling

the target cell is also the secreting cell

vagus nerve

the tenth cranial nerve that innervates digestive organs, heart and other areas

What happens with sickle cell anemia?

tissue damage can occur due to not getting enough oxygen (oxygen depravation) The abnormal valine residue is hydrophobic and replaces a hydrophilic residue (glutamate) on the surface of the folded polypeptide. Hydrophobic interactions between the abnormal residues on the protein's surface lead to the formation of gigantic macro polymers (many hemoglobin molecules stuck together) which become so large that they distort red blood cells.

A cell has three copies of a gene. All of the following are possible causes of this:

translocation non-disjunction during meiosis anaphase I non-disjunction during meiosis anaphase II