CHEMISTRY QUESTIONS
coordinate covalent bond
a covalent bond in which one atom contributes both bonding electrons
Heme consist of what kind of ring structure?
a porphyrin. The basic unit of a porphyrin is the pyrrole ring, a five-sided heterocycle containing one nitrogen atom.
Cooperativity would be presented by what kind of slope on a graph?
a sigmoidal curve (think hemoglobin)
The ion responsible for the color of the solutions is: A. sulfate, because sulfur has s and p orbitals. B. nickel(II), because it has a charge of +2. C. nickel(II), because it has unfilled d orbitals. D. sulfate, because it is a resonance-stabilized anion.
(basically, Low energy d orbitals absorb visible light and when unfilled they can change the color of a solution. We need to memorize that transition metals produce colors because of d orbital transitions.)
Intermolecular vs intramolecular forces
*Intermolecular* forces exist *between* molecules *Intramolecular* forces exist *within* molecules .
Nucleophile
- donates electrons ( the more (-) the better) - the more electronegative the WORSE of a nucleophile because they want to hang on to charge more tightly - steric hindrance = BAD nucleophile - polar protic solvent (H bond donors) = nucleophelicity increases going down a column - polar aprotic solvent (lacking H bonds) = nucleophelicity increases going up a column
Thin Layer Chromatography Important concepts - elution strength -mobile phase - retention factor
- the mobile phase is NONpolar - elution strength depends on how strongly a compound adsorbs onto the adsorbent. Since typical adsorbents are highly polar, eluting strength INCREASES with increasing solvent POLARITY. - retention factor - Polar compound have SMALLER Rf, Nonpolar have LARGE Rf value
If an archaebacterial species lives in a pool that is 0.01 M HCl(aq), what is the pH of the water? A. 12 B. 6 C. 2 D. 0.01
-10^pH = [H+] -10^pH = 10^-2 --> (0.01) pH = 2
What is the pH of a 0.10 M aqueous solution of acetylsalicylic acid? A. 1.0 B. 2.3 C. 3.5 D. 4.1
10^-3.5(0.1) = x^2 10^-4.5 = x^2 [10^-2.25][10^-2.25] = x^2 10^-2.25 = x x = 2.25
How many moles of ethanol are contained in a sample of 30 ml at 8 celsius? (density = 0.800 g/ml and mw = 46.08 g/mol) ** Avogadros # = 6x10^23
30 ml x 0.800 g/ml = 24 g 24 g /46.08 g/mol = 0.500 mol 0.500 mol x 6x10^23 = 3x10^23
pyrrole ring
4 membered ring containing NITROGEN as a part of heme group
What is Avogadro's number?
6.02 x 10^23
If the reaction shown in Equation 1 is spontaneous, the value of K must be: A.greater than 1. B.equal to ΔG. C.less than 1. D.equal to zero.
A
Which of the bromomethanes is LEAST polar? A. CBr4 B. CHBr3 C. CH2Br2 D. CH3Br
A is correct The polarity of the molecule depends on the INDIVIDUAL bond polarities within it. Since the Br atom polarities all cancel each other out in choice A it is least polar.
what does a Keq of 1 tell you about a reaction?
A key of 1 means that a reaction is thermoneutral meaning no ATP is consumed or created and G = 0
What does a large equilibrium constant (K) tell you about the thermodynamics of a reaction?
A large equilibrium constant K>1 means that the reaction is EXOTHERMIC and has a NEGATIVE gibbs free energy
What is the formula for calculating the amount of stereoisomers possible?
A molecule with n stereo centers will have 2^n stereoisomers
Positive control vs. negative control
A positive control is a control group that is not exposed to the experimental treatment but that is exposed to some other treatment that is known to produce the expected effect. A negative control group is a control group that is not exposed to the experimental treatment or to any other treatment that is expected to have an effect.
What is the geometry of the hexafluoroaluminate ion (AlF63-)? A. Octahedral B. Tetrahedral C. Trigonal bipyramidal D. Hexagonal
A. octahedral
What types of functional groups act to form the imine intermediate in the streaker synthesis of amino acids?
Aldehyde + Ammonia!
Is glucose and aldose or a ketone?
Aldose
What is the function of an indicator in titration and what is the ideal pKa of such a solution?
An indicator changes color near the titration end point, therefore the indicator should have a pKa within 1 unit of the pH of the solution.
How many sodium ions are in the initial 50.00-mL solution of Na2CO3 x 10H20 that contains 7.15 g Na2CO3? A. 1.50 × 10^22 B. 3.00 × 10^22 C. 6.02 × 10^23 D. 12.0 × 10^23
Answer is B The solution contains 7.15 g Na2CO3×10H2O. Dividing by the molar mass will give the number of moles: (7.15 g)/(286.14 g/mol) = 0.0250 mol. Because each mole of Na2CO3 × 10 H2O contains 2 mol Na+, there is 0.0500 mol Na+. Using Avogadro's number, the number of sodium ions is (0.0500 mol)(6.02 × 10^23 ions/mol) = 3.01 × 10^22 ions. Thus, B is the best answer.
What does a phosphatide consist of?
Any of a class of compounds which are fatty acid esters of glycerol phosphate with a nitrogen base linked to the phosphate group.
What is the electronic configuration of the Co(II) center found in vitamin B12? A. [Ar] 3d7 B. [Ar] 4s2 3d5 C. [Ar] 4s2 3d7 D. [Ar] 4s2 4d5
Aufbau principle, which states that 4s fills before 3d. But a 3d orbital is not higher-energy than a 4s one, and it is the 4s orbital that is located farther from the nucleus, with a higher principal quantum number. When finding the electron configuration of a cation, you want to remove electrons from the outermost orbitals first. Here, you take two electrons from the 4s orbital before taking any from 3d. You'd do the same if the distinction was, say, between 5s and 4d - you take the electrons from 5s first.
Which of the following is NOT required to develop a DNA fingerprint from a small sample of DNA? A. PCR B. Restriction enzymes C. Transformation D. Electrophoresis
C Transfomation would alter the DNA you are trying to analyze
The association constant Ka, of epithelial growth factor receptors binding to epithelial growth factors is 5.61x10^6. What is the Key of this reaction? A. 5.61x10^6 B. 6.1x10^7 C. 2.8x10^-6 D. 4.5x10^4
The answer is A Ka = Keq!! Because they are at EQUILIBRIUM!
Calcium and magnesium belong to what group on the periodic table? A.The alkali metals B.The metalloids C.The alkaline earth metals D.The halogens
C
Gel electrophoresis works by separating the pieces of a protein by: A. isoelectric point. B. polarity. C. size. D. side chain acidity.
C
Which of the following statements most accurately describes the solubility properties of fatty acid salts? A. They are soluble in polar media only. B. They are soluble in nonpolar media only. C. They can partially dissolve in both polar and nonpolar media. D. They are completely insoluble in both polar and nonpolar media.
C is correct
What is the minimum number of moles of CaSO4(s) that must be added to one liter of water in order to create a saturated solution if the Ksp of CaSO4(s) is 9.1 x 10-6? A. 9.10 x 10-3 B. 1.74 x 10-6 C. 3.02 x 10-3 D. 3.02 x 10-6
CaSO4 --> Ca^2+ + SO4^2- so Ksp = [Ca^2+][SO4^2-] = x^2 sort of 9.1x10^-6 = 3.02x10^-3
stereospecific reaction
Different isomers lead to isomerically opposite products. --> Any reaction that is stereospecific is also stereoselective, but the converse is not true! SAME product but different isomers (can NOT be a different product)
inductive effect
Electron donation or withdrawal through adjacent sigma bonds of a molecule.
Apoenzyme ("Apot is missing")
Enzymes lacking their cofactors, which are REQUIRED for their function, are known as apoenzymes
tollens test
Gives a "silver mirror" product for reducing sugars. REDUCING sugars are hemiacetals (glucose) in their ring form and either aldehydes or ketones in their straight-chain form.
Oligosaccharides are bound together by what type of bond?
Glycosidic linkage (glycoside bond)
hydrogen peroxide
H2O2
Sulfuric Acid
H2SO4
Phosphoric Acid
H3PO4
How do impurities affect: 1. Boiling point 2. melting point
Impurities in solids typically LOWER the melting point because they disrupt the pristine crystal lattice. Adding impurities to a liquid typically INCREASES the boiling point
How would I determine catalytic efficiency of a reaction?
Kat/Km
What is the normality of a 0.015 M solution of phosphoric acid? (H3PO4) A. 0.015 N B. 0.030 N C. 0.045 N D. 0.060 N
Normality = #of H x Molarity = 3 x 0.015 M = 0.045 M
Boyle's Law
P1V1=P2V2
phosphate
PO4 3-
Describe R and S and D and L configurations in terms of relative and absolute configurations.
R and S are absolute configurations D and L are relative configuration - can't assume D and L, has to be measured
On a chromatography plate, the solvent front (water) traveled 10 units. Aspartic acid, traveled 2 units. What is the Rf value of aspartic acid? A. 0.20 B. 0.50 C. 5 D. 10
Rf value = NONpolarity so a POLAR compound would have a very LOW Rf value Rf value = distance traveled by Asp/distance traveled by solvent = 2/10 = 0.2
Le Chatelier's Principle
States that if a stress is applied or removed to a system at equilibrium, the system shifts in the direction that relieves the stress or makes up for a shift.
How does suicide inhibition differ from other types of inhibition?
Suicide inhibition occurs when an enzyme binds the inhibitor and forms an irreversible complex with it, usually through a covalent bond.
Tautomerism
Tautomers are isomers of a compound which differ only in the position of the protons and electrons.
During strenuous exercise, lactic acid buildup in cells causes the creation of a hydronium complex known as the Eigen cation (H9O4+). If water molecules then experience hydrogen bond attractions to the Eigen cation, this attractive force: A. results in a semi-stable shell of water molecules around the hydronium. B. results in an inability of hydronium to be neutralized by bases the way normal H+ ions would be. C. results in the ability of muscle cells to reverse both the hydronium creation process and the lactic acid creation process once sufficient oxygen is once again made available. D. results in mobility of hydronium within the environment surpassing the mobility of regular water molecules.
The answer is A
Four organic compounds: 2-butanone, n-pentane, propanoic acid, and n-butanol, present as a mixture, are separated by column chromatography using silica gel with benzene as the eluent. What is the expected order of elution of these four organic compounds from first to last? A.n-Pentane → 2-butanone → n-butanol → propanoic acid B.n-Pentane → n-butanol → 2-butanone → propanoic acid C.Propanoic acid → n-butanol → 2-butanone → n-pentane D.Propanoic acid → 2-butanone → n-butanol → n-pentane
The answer is A
Gamma decay occurs when a nucleus emits: A. photon. B. a proton. C. a neutron. D. an electron.
The answer is A
Increasing the rate of gluconeogenesis would also increase activity in which of the following processes or enzymes? Glycolysis FBPase Oxidative phosphorylation A. II only B. III only C. II and III only D. I, II, and III
The answer is A
One method of isolating polypeptides and proteins from aqueous extracts is freeze drying. The aqueous solution of the polypeptide or protein is frozen. What procedure can be used to remove the water from the frozen sample? A. Sublimation under reduced pressure B. Distillation using steam C. Extraction with organic solvent D. Addition of magnesium sulfate
The answer is A
Suppose that at the end of a Reaction the level of the aqueous solution were 26 cm higher inside the buret than outside. Compared to ambient pressure, the pressure of the gas inside the buret would be: A.lower. B.the same. C.2 times greater. D.26 times greater.
The answer is A
Which of the following correctly describes the orbital hybridizations of XeF4 and NH3? A. sp3d2, sp3 B. sp3, sp3 C. sp3, sp2 D. sp3d2, sp2
The answer is A - XeF4 is sp3d2 because it Xe has 8 valence electrons, 4 bonds (4e) and 2 lone pairs (4e) 4 Bond + 2 lone pairs = 6 regions of electron density meaning sp3 (4 regions) has to have 2 d added to make 6 - NH3 = sp3 because there are 4 regions of electron density (3 bond and 1 lone pair)
A compound was analyzed and found to contain 12.0 g carbon, 2.0 g hydrogen, and 16.0 g oxygen. What is the empirical formula for this compound? A. CH2O B. C6HO8 C. C6H12O6 D. C12H2O16
The answer is A Carbon mw: 12 g/mol = 1 C Oxygen mw: 16 g/ mol = 1 O Hydrogen mw: 1 g/mol = 2 H Ratio = 1:2:1 --> CH2O
The principal quantum number is a measure of which of the following? A. Approximate radial size of an electron cloud B. Approximate shape of an electron cloud C. Number of valence electrons that orbit a nucleus D. Number of protons and neutrons found in the nucleus of an atom
The answer is A Choice B is false as it is the azimuthal quantum number (l), which determines the shape of an orbital (s, p, d, etc.). Choice C can be eliminated, as each electron has its own quantum number, not just the valence electrons as the choice suggests. Choice D can be eliminated as the sum of the protons and neutrons in the nucleus comprise the atomic mass of the atom, and have nothing to do with electronic quantum numbers.
Substituting residues in a peptide with which amino acid will most likely result in a peptide with an increased pI? A. Lys B. Glu C. Gln D. Val
The answer is A Lys = basic aa , which INCREASE pI Glu = acidic aa, which DECREASES pI Gln and Val = neutral, do NOT affect pI
Hemolytic anemia may result from increased free radical levels in red blood cells. Primaquine, an oxidant drug, reduces cellular production of NADPH, and some individuals suffer from hemolytic anemia after primaquine treatment. Which enzyme is most likely affected in these individuals? A. Glucose-6-phosphate dehydrogenase B. Ribulose-5-phosphate isomerase C. Hexokinase D. Carboxypeptidase
The answer is A NADPH is critical to the function of antioxidants (such as glutathione) that are important in maintaining the integrity of red blood cells. The pentose phosphate pathway is the primary source of this NADPH and glucose-6-phosphate dehydrogenase (G6PDH) is the first and regulated step of this pathway. Its inhibition would lead to a decrease in NADPH levels and impair red blood cells' capacity to cope with oxidative stresses
What is the best explanation for the fact that a solution of NaNO2(aq) is basic? A. NO2- is hydrolyzed with the formation of OH -(aq) ions. B. Na+ is hydrolyzed with the formation of OH -(aq) ions. C. NaNO2(aq) decreases the Ka of HNO2(aq). D. NaNO2(aq) increases the Ka of HNO2(aq).
The answer is A NO2 wants to accept an H (BASIC) making OH int he process
H2O is liquid at room temperature, whereas H2S, H2Se, and H2Te are all gases. Which of the following best explains why H2O is liquid at room temperature? A. Hydrogen bonds form between H2O molecules. B. Oxygen lacks d orbitals. C. H2O has a lower molecular weight. D. H2O is more volatile.
The answer is A ONLY H20 can for intermolecular H bonds, the others can't
What is the approximate pH of a saturated aqueous solution of hydrochloric acid whose molarity is 10.6 M? A. -1 B. 1 C. 7 D. 13
The answer is A When strong acid has a concentration greater than 1 M the pH value becomes negative If hydroxide is greater than 1 M the pH is greater than 14
Which type of bond is formed by glycogen synthase upon release of UDP? A. α-1,4-Glycosidic bond B. α-1,6-Glycosidic bond C. β-1,4-Glycosidic bond D. β-1,6-Glycosidic bond
The answer is A You should know that glycogen synthase adds on the glucose to glycogen through alpha-1,4 bonds whereas branching enzyme will create different branches of glucose via alpha-1,6 bonds
In unimolecular nucleophilic substitution (SN1), a nucleophile attacks an electrophile. The rate law of the reaction is first order overall, and first order with respect to the electrophile. Which of the following, if true, would NOT support this statement? A. Diluting the reaction has no effect on the rate. Correct Answer B. Doubling the concentration of nucleophile has no effect on the rate. C. Increasing the concentration of electrophile increases the rate. D. The rate constant has units of reciprocal seconds.
The answer is A diluting the reaction WILL affect the reaction rate because you are diluting the electrophile! The nucleophile will not affect the reaction because it is not included in the rate law
The pH range of blood under normal physiological conditions is between 7.37-7.42. After 18 hours of treatment on aspirin, the patient's blood hydrogen ion concentration is: A. above the concentration under normal physiological conditions. B. in the same range as normal physiological conditions. C. below the concentration under normal physiological conditions. D. cannot be determined.
The answer is A its higher because more H ion = MORE acidic
Protein secondary structure is characterized by the pattern of hydrogen bonds between: A.backbone amide protons and carbonyl oxygens. B.backbone amide protons and side chain carbonyl oxygens. C.side chain hydroxyl groups and backbone carbonyl oxygens. D.side chain amide protons and backbone carbonyl oxygens.
The answer is A secondary structure is in the backbone NOT among side chains (that is tertiary structure)
After adding the fertilizer that pushes the direction of a reaction to produce more OH ions, which of the following would be true? A. The degree of ionization will be greater, releasing more OH-. B. The degree of ionization will be greater, consuming more OH-. C. The degree of ionization will be reduced, releasing more OH-. D. The degree of ionization will be reduced, consuming more OH-
The answer is A the degree of ionization would be greater in this reaction because the reaction is being pushed in the direction of producing a STRONG acid. If it were going from a strong acid to a weak acid, the degree of ionization would decrease.
Where are nonmetals found in the periodic table? A. Right side B. Left side C. Top half D. Bottom half
The answer is A the halides are nonmetals
The C=S double bond consist of a combination of 1 sigma bond an 1 Pi bonds. Compared to the bind dissociation energy of a Pi bind, the dissociation energy required to break a sigma bond is? A. greater B. less C. the same D. proportional
The answer is A Pi bonds are strong than sigma bonds when they are considered in the SAME bond Pi bonds are less stable than sigma bod when they are considered SEPARATELY so.. the sigma bond would be harder to break because it is at a lower energy state that is more stable.
When experiments are performed on enzymes that display traditional Michaelis-Menten kinetics, what shape does the graph of V0 versus substrate concentration [S] have? A. A hyperbolic dependence on [S] B. A linear dependence on [S] C. A sigmoidal dependence on [S] D. A parabolic dependence on [S]
The answer is A Think Competitive inhibition....First up then levels off at top
If sodium sulfate was added to the mixture containing silver ions and the yellow precipitate, what might be observed after a significant amount of time elapsed? A. Little to no silver sulfate formation, because the Ksp of silver sulfate is very large compared to the Ksp of the yellow precipitate. B. Little to no silver sulfate formation, because sodium sulfate cannot be dissolved at all in water. C. Significant silver sulfate formation, because the solubility of sodium sulfate releases sodium ions which catalyze the necessary reactions. D. Significant silver sulfate formation, because the solubility of sodium sulfate releases sulfate ions which catalyze the necessary reactions.
The answer is A a LARGE Ksp = MORE soluble than a lower kip
Which single bond present in nitroglycerin is most likely the shortest? A.C-H B.C-O C.C-C D.O-N
The answer is A because H has tiny radius compared to group 2 elements like C,O and N
In which of the following molecules does the carboxylic acid functional group have the highest Ka? A. CH3CF2COOH B. CHF2CH2COOH C. CH3CHFCOOH D. CH3CH2COOH
The answer is A because the 2 F's withdraw electrons from the O and are located closely enough to the O groups to have an inductive effect
What are the structural features possessed by storage lipids? A.Two fatty acids ester-linked to a single glycerol plus a charged head group B.Three fatty acids ester-linked to a single glycerol C.Two fatty acids ester-linked to a single sphingosine plus a charged head group D.Three fatty acids ester-linked to a single sphingosine
The answer is B
Which biochemical pathway is most involved with the neutralization of oxygen radicals? A. Glycolysis B. Pentose Phosphate Pathway C. Gluconeogenesis D. Fatty Acid Oxidation
The answer is B
Which of the following lipids is a key component of myelin sheaths? A. Terpenes B. Sphingolipids C. Prostaglandins D. Tocopherols
The answer is B
Which of the following statements about glycolysis or gluconeogenesis is FALSE? A. Glycolysis is overall an exergonic reaction. B. Glycolysis requires the input of two ATP molecules for the breakdown of each glucose molecule and is therefore overall an endergonic reaction. C. High citrate levels would stimulate gluconeogenesis but not glycolysis. D. Both glycolysis and gluconeogenesis are exergonic reactions.
The answer is B
Assuming a 95% yield for each coupling step, what would be the final yield for synthesizing a 10 amino-acid length peptide? A. 30% B. 60% C. 80% D. 95%
The answer is B 5% lost every step, 10 AA, except the first which is 100% so 9x5 = 45% lost = 55% However, not exactly 5% of a hundred is lost in each step but rather 5% of 95 etc.... so the values is a little bit bigger = 60%
Which of the following is NOT considered an organic acid? A. Folic acid B. Carbonic acid C. Ascorbic acid D. Citric acid
The answer is B An organic compound must contain carbon and hydrogen in its formula. Furthermore, there must be a covalent bond between a carbon and hydrogen atom in the molecular structure. Organic acids are weak acids, generally having formulas of R-CO2H, with the acidic hydrogen bonded to an oxygen atom.
In the electron transport chain, which of the following is the component that is reduced but never oxidized? A. Ubiquinone B. Oxygen C. Nicotinamide adenine di-nucleotide D. ADP
The answer is B At the end of the chain, oxygen is reduced to form H2O, which is the end fate of the electrons in the chain.
Which of the following peptides is most likely to form a covalently bonded dimer? A. AVTSYWP B. GHICEPN C. NFMNELI D. ELIPWQN
The answer is B Cysteine is present meaning a disulfide linked dimer can form
When choosing a buffer to use for an experiment conducted at pH 5.3, it would be best to choose one with a pKa of: A .2.14. B. 4.75. C. 6.5. D. 7.0.
The answer is B Good experimental design protocols state that a good buffer has a pKa WITHIN 1 pH unit of the desired experimental conditions.
Each of the following equations shows the dissociation of an acid in water. Which of the reactions occurs to the LEAST extent? A. HCl + H2O → H3O+ + Cl− B. HPO42− + H2O → H3O+ + PO43− C. H2SO4 + H2O → H3O+ + HSO4− D. H3PO4 + H2O → H3O+ + H2PO4−
The answer is B HPO4^2− has a high negative charge and so dissociation of it will occur to the least extent. The higher the charge on the ions, the higher their electrostatic attraction making it harder for water to pull them apart.
The ATP-dependent phosphorylation of a protein target is catalyzed by which class of enzyme? A. Oxidoreductase B. Transferase C. Hydrolase D. Ligase
The answer is B Oxidoreductase -catalyzes the transfer of electrons from one molecule, the reductant, also called the electron donor, to another, the oxidant, Transferase -A transferase is any one of a class of enzymes that enact the transfer of specific functional groups Hydrolase - breaks bond Ligase - fuses DNA
The conversion between glucose and pyruvate strongly favors the formation of pyruvate, and yet the gluconeogenic pathway is able to utilize several shared enzymes with glycolysis to create glucose from pyruvate. It is able to do this primarily because: A. the formation of glucose from the gluconeogenic precursors is strongly favored by the increasing entropy of the reaction. B. the formation of glucose, fructose-6-phosphate, and PEP through gluconeogenesis-specific enzymes push the equilibrium of reactions catalyzed using shared enzymes to favor gluconeogenesis. C. the activity of the enzymes with two or more functions is reversed when those enzymes are altered by kinases. D. enzymes in gluconeogenesis bypass reversible, equilibrium-state steps common to both pathways.
The answer is B Production of PEP, glucose, and fructose 6-phosphate by gluconeogenesis-specific enzymes that bypass irreversible steps of glycolysis push the equilibrium of reversible enzymes that function both in glycolysis and gluconeogenesis in the direction of glucose production.
What is the best explanation for the fact that a solution of NaNO2(aq) is basic? A. NO2- is hydrolyzed with the formation of OH -(aq) ions. B. Na+ is hydrolyzed with the formation of OH -(aq) ions. C. NaNO2(aq) decreases the Ka of HNO2(aq). D. NaNO2(aq) increases the Ka of HNO2(aq).
The correct answer is A NO2 + H20 --> NH + OH
Alcohols generally require acid catalysis in order to undergo substitution by nucleophiles. The acid catalyst enhances the reaction by: A. increasing the solvent polarity. B. creating a better leaving group. C. neutralizing basic impurities. D. protecting the alcohol group.
The answer is B The substitution reaction in question serves to replace the hydroxyl group and that hydroxide ion is one of the WORST leaving groups in substitution reactions. Under acidic conditions, the hydroxyl group is protonated such that the leaving group is now water, a superior leaving group,
Which of the following is most likely the net charge on a valine molecule in the human body? A. -1 B. 0 C. +5 D. +1
The answer is B Valine is an uncharged hydrophobic AA meaning that at pH 7 the amino group will be protonated while the carboxyl group will be deprotonated
A protein contains four disulfide bonds. In order to break these bonds researchers added a minimum of: A. 2 moles of NADH for each mole of protein. B. 4 moles of NADH for each mole of protein. C. 2 moles of NAD+ for each mole of protein. D. 4 moles of NAD+ for each mole of protein.
The answer is B each mole of NADH can reduce a mole of disulfide bonds. Since the protein has four disulfide bonds, four moles of NADH are needed.
Which of the four DNA bases contains the largest number of hydrogen bond acceptors when involved in a Watson-Crick base pair? A. A B. C C. G D. T
The answer is B guanine contains 2 donors and 1 acceptor, and cytosine contains 1 donor and 2 acceptors.
What is the pH of a buffer solution that is 0.2 M in HCO3- and 2 M in H2CO3? (Note: The first pKa of carbonic acid is 6.37.) A.4.37 B.5.37 C.6.37 D.7.37
The answer is B pH = pka + log [A]/[HA] pH = 6.37 + log [0.2]/[2] 0.2/2 = 1/10 or 0.1 or 10^-1 pH = 6.37 + 10^-1 = 6.37 - 1 pH = 5.37
In [Cu(NH3)4]2+, the subscript 4 indicates which of the following? A.The oxidation number of Cu only B.The coordination number of Cu2+ only C.Both the oxidation number of Cu and the coordination number of Cu2+ D.Neither the oxidation number of Cu nor the coordination number of Cu2+
The answer is B the subscript 4 tells us the amount of ammonia, nothing else. So 4 ammonium ions will surround the Cu = coordination #
Which of the following would not be observed in an individual with an increased rate of protein degradation? A. Increased alanine in the bloodstream B. Increased urea synthesis in muscle tissue C. Increased ammonia excretion D. Increased use of carbon skeletons in the Krebs cycle
The answer is B Urea is not synthesized in muscle tissue
The conjugate base of phosphoric acid is: A. H3PO4 B. H2PO4- C. HPO42- D. PO43-
The answer is B phosphoric acid = H3PO4 conjugate base would have 1 less H = H2PO4-
Channel X transmits only the smallest substances dissolved in the extracellular fluid through the axon membrane. Which substance does Channel X transmit? A. Proteins B. Sodium ions C. Potassium ions D. Chloride ions
The answer is B A cation (like Na) will ALWAYS have a smaller radius than an anion (like Cl)
What is the molar concentration of Na+(aq) in a solution that is prepared by mixing 10 mL of a 0.010 M NaHCO3(aq) solution with 10 mL of a 0.010 M Na2CO3(aq) solution? A. 0.010 mole/L B. 0.015 mole/L C. 0.020 mole/L D. 0.030 mole/L
The answer is B since 1 equivalent of NaHCO3 provides 1 equivalent of Na+, the molar concentration of Na+(aq) in 0.010 M NaHCO3(aq) solution is also 0.010 M = 0.010 mole/L. The molar concentration of Na+(aq) in 0.010 M Na2CO3(aq) solution is 0.020 mol/L since 1 equivalent of Na2CO3 provides 2 equivalents of Na+. When equal volumes of these two solutions are mixed, the resulting molar concentration is equal to their average, (0.010 mol/L + 0.020 mol/L)/2.
When two amino acids are joined via a peptide bond, what is the mass of the byproduct of this reaction? (Note: Assume that the amino acids were not modified by protecting groups.) A.17 amu B.18 amu C.32 amu D.44 amu
The answer is B because the byproduct is water
To a first approximation, the ionization constant of H2S is: A. near zero. B. much less than 1. C. about 1. D. much more than 1.
The answer is B since H2S is a weak acid
Inhibition of phosphofructokinase-1 by ATP is an example of: I. allosteric regulation. II. feedback inhibition. III. competitive inhibition. A.I only B.III only C.I and II only D.II and III only
The answer is C
Squalene is produced in the human body as a precursor to which important class of compounds? A. Triacyl glycerols B. Phospholipids C. Steroid hormones D. Prostaglandins
The answer is C
The most likely function of an ebulliator blowing bubbles int a distillation flask? A. keep the condensed vapors cool in the receiving flask. B. promote the establishment of a high vacuum in the system. C. prevent superheating of the liquid to be distilled. D. provide an outlet when the pressure inside the system becomes too high.
The answer is C
The term "ideal gas" refers to a gas for which certain assumptions have been made. Which one of the following assumptions applies to an ideal gas? A. The law PV = nRT2 is strictly obeyed. B. Intermolecular forces are infinitely large. C. Individual molecular volume and intermolecular forces are negligible. D. One mole occupies a volume of 22.4 L at 25°C and 1 atm pressure.
The answer is C
What type of functional group is formed when aspartic acid reacts with another amino acid to form a peptide bond? A. An amine group B. An aldehyde group C. An amide group D. A carboxyl group
The answer is C
Why is the velocity of blood flow slower in capillaries than in arteries? A. Capillary walls are more elastic than arterial walls. B. Capillaries have less resistance to blood flow than arteries. C. The total cross-sectional area of capillaries exceeds that of arteries. D. Blood pressure is higher in the capillaries than in arteries.
The answer is C
Ignoring stereochemistry, how many different tripeptides may exist that contain the same three amino acids? A. 1 B. 3 C. 6 D. 9
The answer is C # of AA combinations = n! so if there are n=3 AA then (3+2+1 = 6)
A certain metabolic process in the liver produces NADH as a part of the process. If this process is up-regulated, which of the following effects associated with gluconeogenesis is most likely to follow? A. Intracellular levels of oxaloacetate will increase. B. Plasma glucose concentrations will increase significantly. C. The rate of gluconeogenesis in the liver will decrease. D. Plasma glucose concentrations will decrease significantly.
The answer is C A. OAA would decrease because the CAC makes NADH, if this is amplified there will be a low level of NAD, ultimately decreasing OAA B. Glucose will decrease because a lot of NADH is being produced increasing glycolysis C. Gluconeogenesis will decrease because NADH is drawing it's energy through glycolysis D. We don't know this for sure
Phosphorous acid, a common ingredient used for potable water treatment, has a molecular formula of: A. H3PO5 B. H3PO4 C. H3PO3 D. H3PO2
The answer is C A: This is perphosphoric acid. B: This is phosphoric acid. D: This is hypophosphorous acid.
Which of the following would participate in a base catalyze cleavage of a FA? A. HCl (aq) B. NaCl (aq) C. NaOH (aq) D. Na2SO4 (aq)
The answer is C B and D are salt and A is an acid
What is the concentration of Ca2+(aq) in a saturated solution of CaCO3? (Note: The solubility product constant Ksp for CaCO3 is 4.9 × 10-9.) A.2.4 × 10-4 M B.4.9 × 10-5 M C.7.0 × 10-5 M D.4.9 × 10-9 M
The answer is C CaCO3 ---> Ca^2+ + CO3^2- ksp = [Ca^2+][CO3^2-] 4.9x10^-9 = x^2 sort of 4.9x10^-9 or 49x10^-10 = 7x10^-5
Which of the following shows the electron configuration of chlorine in NaCl? A. 1s2-2s2-2p6-3s2-3p4 B. 1s2-2s2-2p6-3s2-3p5 C. 1s2-2s2-2p6-3s2-3p6 D. 1s2-2s2-2p6-3s2-3p4-4s2
The answer is C Chlorine (Cl) turn into chloride ion (Cl-) in NaCl solution meaning it gained ONE MORE e- charge. Therefore it would fill one more p orbital
What is the electron configuration of Co^3+? A. [Ar] 4s^2 3d^4 B. [Ar] 4s^1 3d^5 C. [Ar] 3d^6 D. [Ar] 4d^6
The answer is C Co3+ has six valence electrons, since Co is in group 9. Since all s-shell electrons will be the first removed, all six electrons will be in d-orbitals
What causes duplex DNA with a certain (A + T):(G + C) ratio to melt at a higher temperature than comparable length duplex DNA with a greater (A + T):(G + C) ratio? A.Stronger van der Waals forces of pyrimidines B.Stronger van der Waals forces of purines C.Increased number of hydrogen bonds D.Reduced electrostatic repulsion of phosphates
The answer is C G-C has three H bonds and A-T has only 2 which is why the melting temperature is increased in a DNA rich in GC content
Which of the following molecules or ions are able to undergo hydrogen bonding with itself in solution? I. Bicarbonate anion II. Phosphoric acid III. Carbon dioxide A. I only B. II only C. I and II only D. I, II, and III
The answer is C O, N and F can undergo H bonding
What is the sum of the protons, neutrons, and electrons in strontium-90? A. 90 B. 126 C. 128 D. 218
The answer is C PROTONS = atomic number. #ELECTRONS = #PRTOTONS NEUTRONS can be found by subtracting the atomic number (protons) from the mass number. The atomic number of strontium (Sr) is 38; so the number of neutrons is 90 - 38 = 52. The sum of protons, neutrons, and electrons in strontium is 38 + 38 + 52 = 128.
A man is accidentally exposed to a toxin which binds irreversibly and noncompetitively to pyruvate dehydrogenase. A likely consequence of this ingestion is: A. a decrease in lactic acid concentration in exposed cells. B. an increase in the concentration of acetyl-CoA in exposed cells. C. a decrease in the level of Krebs cycle activity within the exposed cells. D. an increased rate of formation of NADH in exposed cells.
The answer is C Pyruvate is a critical link between glycolysis and CAC (pyruvate DH converts pyruvate --> acetyl CoA) A. lactic acid would increase due to lack of aerobic respiration B. acetyl CoA would decrease D. NADH would be decreased
Which of the following statements explains why the boiling point of HF is abnormally high when compared to the boiling points of other Group 7A hydrides? A. The H-F bond is much less polar than the bonds between H and the other halogens. B. HF has the lowest molecular mass of the Group 7A hydrides. C. HF is affected by hydrogen-bonding interactions to a much greater degree than the other Group 7A hydrides. D. HF has the highest vapor pressure among the Group 7A hydrides.
The answer is C Since hydrogen bonding is a higher than anticipated dipole-dipole interaction, it causes substances that exhibit it to have higher than expected boiling points and lower vapor pressures.
To determine a protein's thermodynamic stability, chemical denaturation studies can be performed. Assuming that only the native and unfolded states can be observed under experimentally available conditions, what is the most likely shape of the curve for the dependence of the fraction of folded protein upon denaturant concentration? A. Hyperbolic B. Linear C. Sigmoidal D. Exponential
The answer is C The unfolding of proteins is a cooperative process which is marled by a sigmoidal curve
Which one of the following general characteristics is shared by all catalysts? A. They induce more collisions among reactant molecules. B. They transfer kinetic energy to the reactant molecules. C. They increase the reaction rate but do not change the Keq of a reversible reaction. D. They increase both the reaction rate and the Keq of a reversible reaction.
The answer is C They decrease the activation energy without affecting Km (affinity)
Which of the following will decrease the percentage ionization of 1.0 M acetic acid, CH3CO2H(aq)? A. Chlorinating the CH3 group B. Diluting the solution C. Adding concentrated HCl(aq) D. Adding a drop of basic indicator
The answer is C When a strong acid is added to the weak acid solutions, since HCl has much more H ions, it will be ionized INSTEAD of acetic acid, decreasing it's ionization energy.
Which of the following is an intermediate of triacylglycerol degradation into glycerol and free fatty acids? A. Acyl-CoA B. Acetyl-CoA C. Water D. Diacylglyceride
The answer is D Fatty acids are removed from the glycerol backbone one by one; therefore, the triacylglycerol will first become a diacylglyceride and a free fatty acid (choice D is correct). Acyl CoA and acetyl CoA are intermediates and products in later steps of the overall degradation process
The iron in Fe-S clusters are known to have reduction potentials ranging in value from -0.65V to +0.45V. Given the fact that aspartate residues in the active site are positioned near the Fe atoms in aconitase, the most likely reduction potential of the iron in Fe-S clusters in aconitase is nearer to: A. +0.45 V since the negative charge on aspartate attracts the Fe atom. B. +0.45 V since the positive charge on aspartate attracts the Fe atom. C. -0.65 V since the negative charge on aspartate attracts the Fe atom. r D. -0.65 V since the positive charge on aspartate attracts the Fe atom.
The answer is C aspartate is negatively charged meaning it would attract Fe eliminate B and D Reducing Fe would decrease it's ability to bond to aspartate (more negative) so it is likely to remain oxidized meaning it will be a negative reduction potential, eliminate A.
Which of the following shows the electron configuration of chlorine in NaCl? A. 1s2, 2s2, 2p6, 3s2, 3p4 B. 1s2, 2s2, 2p6, 3s2, 3p5 C. 1s2, 2s2, 2p6, 3s2, 3p6 D.1s2, 2s2, 2p6, 3s2, 3p4, 4s2
The answer is C in NaCl chlorine exists as an anion at Cl- meaning it has an extra electron, meaning it will move to the RIGHT of the periodic table toward a full shell
According to trends in electronegativity, which of the following pairs of atoms is most likely to form an ionic bond? A. N and O B. C and F C. Ca and I D. Si and Cl
The answer is C ionic bonds are more likely to form between elements that are the furthest apart on the periodic table
The side chain of which amino acid can form a bond that is similar to a peptide bond? A. Gly B. Phe C. Lys D. Ala
The answer is C the lysine side chain can form isopeptide bonds by reacting with a carboxylic acid group, which is the same way that peptide bonds are formed.
If red litmus paper is dipped into the Na2CO3 solution, it will: A. remain red, because carbonate is an acidic salt. B. remain red, because sodium carbonate is neutral. C. turn blue, because carbonate reacts with water to produce OH-. D. turn blue, because sodium ions form sodium hydroxide in water.
The answer is C Red litmus paper will turn blue in a BASE
Which of the following compounds is amphiprotic? A. Acetic acid, HC2H3O2 B. Sodium acetate, NaC2H3O2 C. Sodium bicarbonate, NaHCO3 D. Sodium carbonate, Na2CO3
The answer is C (HCO3 in Blood!!!) Amphiprotic means that the compound is able to act as an acid and as a base. Bicarbonate ion, HCO3-, can act as a Bronsted-Lowry acid by loss of a hydrogen ion and can act as a B-L base by accepting a hydrogen ion to form carbonic acid, H2CO3.
What type of alcohol is most likely to undergo an SN1 reaction in an acidic environment? A. primary B. secondary C. tertiary
The answer is C. Tertiary alcohol will make the most STABLE carbocation (carbocations like to be highly substituted)
The pKa for the dissociation of H2PO4 to HPO4 is 6.7. What is the initial ratio of HPO4:H2PO4 in the buffer solution of Experiment 1 with a pH of 8.7? A. 1:1 B. 2:1 C. 100:1 D. 200:1
The answer is C. 100:1 pH = pKa + log [A/HA] 8.7 = 6.7 + log [HPO4/H2PO4] 2 = log [HPO4/H2PO4] 10^2 = [HPO4/H2PO4] 100 = [HPO4] 1 = [H2PO4]
The energy of activation for a reaction is given by the energy of: A.the reactants minus the energy of the products. B.the products minus the energy of the reactants. C.the activated complex minus the energy of the products. D.the activated complex minus the energy of the reactants.
The answer is D
What is the net charge on a phenylalanine molecule at pH 1? A. -1 B. 0 C. +0.5 D. +1
The answer is D
Which of the following is most likely to inhibit and activate, respectively, isocitrate dehydrogenase, a key enzyme in the Krebs cycle? A. NADH; ATP B. AMP; NADH C. NAD+; ATP D. ATP; NAD+
The answer is D
Which of the following types of orbitals of the central atom are involved in bonding in octahedral compounds? A .sp B. sp3 C. p D. d2 sp3
The answer is D
Which of the following would increase the rate of gluconeogenesis? A. Increasing the concentration of citrate in myocytes B. Decreasing the concentration of ATP in hepatocytes C. Increasing the blood concentration of insulin D. Increasing the blood concentration of glucagon
The answer is D
Which statement correctly describes how enzymes affect chemical reactions? Stabilization of: A. the substrate changes the free energy of the reaction. B. the transition state changes the free energy of the reaction. C. the substrate changes the activation energy of the reaction. D. the transition state changes the activation energy of the reaction.
The answer is D
Assume hydrolysis of ATP proceeds with G = -30 J/mol. ATP + H2O -> ADP + Pi Which expression gives the ratio of ADP to ATP at equilibrium, if Pi = 1.0M? A. e^2 B. e^3 C. e^6 D. e^12
The answer is D - Keq = ([ADP]+[P])/[ATP] - G = -RTln(Keq) - G = -RTln([ADP]+[P])/[ATP]) - ADP/ATP = e^(30/2.5) = e^12
How much sodium hydroxide is needed to completely saponify a triacylglycerol? A. A catalytic amount, because OH- is continuously being regenerated during saponification B. One-third of an equivalent, because each OH- ion reacts to form three fatty acid salts C. One equivalent, because each OH- ion reacts to produce one molecule of glycerol D. Three equivalents, because one OH- ion is required to saponify each of the three fatty acid groups
The answer is D Because there are three ester linkages in a triacylglycerol, three equivalents of sodium hydroxide will be needed to completely saponify the triacylglycerol.
Which of the following alkyl chlorides is most likely to undergo an SN1-type reaction? A. Chloromethane B. Chloroethane C. 2-chloropropane D. 2-chloro-2-methylpropane
The answer is D CARBOCATIONS prefer highly substituted carbons! SN1 forms carbocations
Conversion of pyruvate into glucose requires enzymes present in: A. the interstitial fluid only. B. the mitochondria only. C. the cytosol only. D. both the mitochondria and the cytosol.
The answer is D Conversion of pyruvate to glucose requires its initial conversion into oxaloacetate, in a reaction catalyzed by pyruvate carboxylase in the mitochondria. The rest occurs in the cytosol.
In oxidative phosphorylation, what is the final step? A. O2 is oxidized to produce H2O. B. NADH is oxidized to form NAD+. C. H+ is hydrolyzed to form H2O. D. ADP is phosphorylated to produce ATP.
The answer is D The final major process of aerobic respiration is oxidative phosphorylation, through which the majority of aerobically-derived ATP is synthesized.
During glycolysis, pyruvate CH3C(=O)CO2- is reduced to lactate CH3CH(OH)CO2- by nicotinamide adenine dinucleotide (NADH). What is the balanced reaction for this conversion? A. CH3C(=O)CO2- + 2NADH → CH3CH(OH)CO2- + 2NAD+ B. CH3C(=O)CO2- + 2NADH + 2H+ → CH3CH(OH)CO2- + 2NAD+ C. CH3C(=O)CO2- + NADH + 2H+ → CH3CH(OH)CO2- + NAD+ D. CH3C(=O)CO2- + NADH + H+ → CH3CH(OH)CO2- + NAD+
The answer is D To choose between A and D, use oxidation/reduction half-reactions and add them together. The half-reaction for the reduction of pyruvate is CH3COCO2- + 2H+ + 2e- → CH3CH(OH)CO2-. The half reaction for the oxidation of NADH is NADH → NAD+ + H+ + 2e-. Adding these together, the electrons cancel out, and one of the H+ on the reactant side cancels the H+ on the product side
When used in place of spHM, which peptide would be most likely to achieve the same experimental results? A.FLGFAY B.FLGFQY C.FLGFGY D.FLGFEY
The answer is D When threonine is phosphorylate is becomes NEGATIVELY charged. Therefore it ca be replaced with E = glutamate which is also negatively charged SYT Please Serine, Threonine and Tyrosine can be phosphorylated B is incorrect, even though Q is also polar it does not apply when threonine is phosphorylated
Which of the following best describes the bonds between Cu2+ and the nitrogen atoms of the ammonia molecules in [Cu(NH3)4]2+? A.Ionic B.Covalent C.Coordinate ionic D.Coordinate covalent
The answer is D because the Cu has a 2+ charge is is missing 2 e- so the Nitrogen atom must contribute BOTH bonding e- C. does not exist A. Not ionic because they are too close on the Periodic table
A certain alkyl halide forms a carbocation that is more stable than the carbocation formed from isopropyl bromide. What is the most likely chemical name of the unknown? A. Methyl bromide B. Ethyl bromide C. n-Propyl bromide D. tert-Butyl bromide
The answer is D carbocations like to be substituted and answer choice D is the most branched out carbocation
What is the most stable conformation of trans-1-ethyl-3-isopropylcyclohexane? A. Both substituents are in the equatorial position. Your Answer B. Both substituents are in the axial position. C. The isopropyl group is axial, and the ethyl group is equatorial. D. The ethyl group is axial, and the isopropyl group is equatorial. Correct Answer
The answer is D in TRANS one substituent will always be axial and one equitorial the LARGER will be equatorial
The relative thermodynamic stability of isomeric organic compounds can be inferred from which of the following types of experimental data? A.Boiling points B.UV-visible absorption spectra C.Mass spectroscopic fragmentation patterns D.Heats of combustion
The answer is D less heat from combustion, greater stability.
Which of the following atoms will be expected to have the smallest second ionization energy? A.Na B.C C.O D.Ca
The answer is D metals have LOWER ionization energies than nonmetals. So B and C are already out. Na is in the 1st row meaning it only has 1 valence e- that is does NOT want to give up, whereas Ca has 2 that would be easier to the away
Which experimental condition is NOT necessary to achieve reliable data for Michaelis-Menten enzyme kinetics? A.Initial velocity is measured under steady state conditions. B.Solution pH remains constant at all substrate concentrations. C.The concentration of enzyme is lower than that of substrate. D.The reaction is allowed to reach equilibrium before measurements are taken.
The answer is D once the reaction reaches equilibrium, measurement of Vo will be impossible and the kinetic data will look the same regardless of substrate concentration.
What is the pH of a .001 M NaOH solution? A 0.001 B. 3 C. 7 D. 11
The answer is D pOH = 0.001 10^0.001 = 3 14 - 3 = 11
What is the concentration of Cl- ions in a 0.1 M solution of calcium chloride? A. 0.02 M B. 0.05 M C. 0.10 M D. 0.20 M
The answer is D the formula for calcium chloride is CaCl2 and it produces twice as many Cl- ions as Ca2+ ions in solution when it dissolves.
2 Ag(s) + H2S(aq) → Ag2S(s) + H2(g) What species is the reducing agent in Equation? A. S2- B. H2S C. H+ D. Ag
The answer is D a reducing agents one that becomes oxidized by donating electrons
If a drug inhibited the activity of the Na+/K+ ATPase in neurons, this would result in: A. increased cellular glucose uptake via secondary active transport. B. increased cellular glucose uptake via primary active transport. C. decreased cellular glucose uptake via primary active transport. D. decreased cellular glucose uptake via secondary active transport. Correct Answer
The answer is D glucose is co-transported with sodium. If Na/K ATPase were to be inhibited, Na would not be pumped OUT, destroying the Na gradient for glucose to come in
Lysine and amino acids with similar chemical characteristics in histones most likely promote the interaction of histones with which DNA components? A. Purines B. Pyrimidines C. Deoxyribose D. Phosphate groups
The answer is D because Lysine is BASIC AA meaning it is + charged so it will interact with negatively charged phosphate groups
A sparingly soluble metal hydroxide, M(OH)2 has a molar solubility of S mol/L at 25°C. Its Ksp value is: A. S2. B. 2S^2. C. 2S^3. D. 4S^3.
The answer is D. The Ksp for a substance, AaBb, equals [A]a[B]b. The Ksp for M(OH)2 = [M][OH-]^2. If the solubility of M(OH)2 is S mol/L, then... [M] = S mol/L and [OH-] = 2S mol/L. The Ksp = S(2S)^2 = S(4S^2) = 4S^3. Thus, D is the best answer.
Suppose that CH4(g) reacts completely with O2(g) to form CO2(g) and H2O(g) with a total pressure of 1.2 torr. What is the partial pressure of H2O(g)? A. 0.4 torr B. 0.6 torr C. 0.8 torr D. 1.2 torr
The balanced equation for the complete combustion of CH4(g) is shown below. CH4(g) + 2(O2) (g) → CO2(g) + 2(H2O) (g) The pressure of the gaseous products is 1.2 torr. For every three product molecules, TWO are water. Therefore, the partial pressure of water is 2/3 the total pressure, because the total pressure is a function of the total number but not kind of molecules. Two-thirds of 1.2 torr is 0.8 torr. Thus, answer choice C is the best answer.
What is a common structure in phenol, thiophenol and alkyl benzene? A. aromatic ring B. Carbonyl C. Carboxylic acid D. Alkyl
The correct answer is A
Which of the following properties is associated with the existence of glycine as a dipolar ion in aqueous solution? A. High dipole moment B. High molecular weight C. Low dielectric constant D. Low solubility in water
The correct answer is A
Which of the following mixtures, with each component present at a concentration of 0.1 M, has a pH closest to 7? A. HClO (aq) and NaClO (aq) B. HNO2 (aq) and NaNO2 (aq) C. CH3COOH (aq) and NaCH3COO (aq) D. HNO3 (aq) and NaNO3 (aq)
The correct answer is A When the acid and conjugate base concentrations are equal, the pH of a buffer equals the pKa of the acid. (lowest Ka)
When 2.0 mL of 0.1 M NaOH(aq) is added to 100 mL of a solution containing 0.1 M HClO(aq) and 0.1 M NaClO(aq), what type of change in the pH of the solution takes place? A. A slight (<0.1 pH unit) increase B. A slight (<0.1 pH unit) decrease C. A significant (>1.0 pH unit) increase D. A significant (>1.0 pH unit) decrease
The correct answer is A the pH will only slightly increase because the strong base is being added to a buffer solution (weak acid + weak base)
Vinblastine is a microtubule disrupting drug that inhibits tubulin polymerization. Which of the following processes would be directly affected by thi I. Phagosome transport into the lysosome II. Mitosis III. Meiosis IV. Electron transport A. II only B. I and IV C. II and III D. I, II and III
The correct answer is D - Microtubules assist in transport of vesicles for membrane bound organelles - microtubules form the spindle apparatus necessary for BOTH mitosis and meiosis
When performing experiments to measure the kcat of an enzyme, the substrate concentration should be: A. limiting. B. equal to 1/2 KM. C. equal to KM. D. saturating.
The correct answer is D You need to have the enzyme saturated with substrate in order to determine is't maximum reaction rate
Define activation energy
The energy needed to overcome that of the reactants for the reaction to move forward = activated complex - reactant energy
If molecular disorder increases during a reaction (spontaneous) will the energy of the reactants or products be greater?
The energy of the products will be less than that of the reaction because an increase in entropy = and increase in energy
What would be the ionization constant of a strong acid as compared to a weak acid?
The ionization constant of a weak acid would be much less than one whereas the ionization constant of a strong acid would be much larger
What does Kb mean?
The value of Kb is given as Kw/Ka If the Kb is > than the Ka the solution is BASIC
What type of isomers are alpha and beta sugars?
They are anomers are a form of epimer. Epimers are sugars that differ only at one stereocenter, with all other stereocenters being exactly the same. Thus, epimers are a type of diastereomer. alpha OH group points DOWN, beta OH group points UP
If an enzyme, PDK1 catalyzes the addition of phosphate to Serine and Threonine AA, what functional group would be involved in this reaction? A.Hydroxyl B.Amine C.Carboxyl D.Phenyl
Threonine and Serine STCY's Not Qute --> POLAR serine and threonine specifically have an OH hydroxyl group
Charles' Law
V1/T1=V2/T2
Under what conditions do deviations from the ideal gas law occur?
When temp is low and pressure is high
pka = -log ka
When the acid and conjugate base concentrations are equal, the pH of a buffer equals the pKa of the acid.
What is the product of B- decay of I-131?
Xe-131 B- decay means an electron is emitted so it moves tot he right on the periodic table MOLECULAR WEIGHT IS NOT AFFECTED
For the balanced reaction below, how many grams of NO are produced for every 16g of O2 that react? 4(NH3) + 5(O2) --> 4(NO) + 6(H2O)
You would calculate this by: 16 g O2 / 32 g/mol O2 x 4 mol NO/5 mol O2 x 30 g NO = 12 g NO
2 R2NBCl2 + 5 LiPH2 → 4 LiCl + 3 PH3 + Intermediate What is the maximum volume of PH3(g) that a chemist can obtain from the reaction shown by Equation 1a, if 0.005 mol LiPH2 reacts with 0.002 mol R2NBCl2 at 0oC and 1 atm? A. 0.672 mL B. 6.72 mL C. 67.2 mL D. 67.2 L
according to the equation we get 3 mol of PH3 so this would end up giving you 0.003 and then multiplying that by 22.4 (STP) to give you C
holoenzyme ("Whole-o enzyme")
enzyme that is functioning on its own
What are the hydrophobic amino acids?
glycine (G), alanine (A), valine (V), leucine (L), isoleucine (I), proline (P), phenylalanine (F), methionine (M) She's a "VIP GAL"
resonance structure
one of the two or more equally valid electron dot structures of a molecule or polyatomic ion (NO MOVEMENT OF ATOMS)
2HCl(aq) + Mg(s) → MgCl2(aq) + H2(g) What type of reaction is this? A. Oxidation/reduction B. Lewis acid/Lewis base C. Double replacement D. Ionization
the answer is A
Which of the following is a second period element that is a covalent network solid in its standard state? A.Carbon B.Phosphorous C.Oxygen D.Iodine
the answer is A
Which of the following properties is associated with the existence of glycine as a dipolar ion in aqueous solution? A. High dipole moment B. High molecular weight C. Low dielectric constant D. Low solubility in water
the answer is A
What is the minimum amount of heat energy required to increase T from 373 K to 573 K? (Note: The specific heat capacity of iron is 460 J/kg·K.) A. 368 J B. 550 J C. 1840 J D. 3680 J
the answer is A The heat q required is given by the relation q = mCΔT, where m is the mass of the iron, C is the specific heat of the iron, and ΔT is 200 K. The answer is q = (4 × 10-3 kg)(460 J/kg·K)(200 K) = 0.8 × 460 J = 368 J
What is the maximum number of moles of nickel carbonate (NiCO3) that can form during the precipitation reaction? A. 0.025 mol B. 0.25 mol C. 1.00 mol D. 2.25 mol
the answer is A There is 0.025 mol Ni from NiSO4×6H2O: (6.57 g)/(262.84 g/mol) = 0.025 mol. There is also 0.025 mol CO32- from Na2CO3×10 H2O: (7.15 g)/(286.14 g/mol) = 0.0250 mol. The maximum number of moles of NiCO3 that can form is 0.025 mol. Thus, A is the best answer.
The overall reaction scheme for enzymes of the CYP450 enzyme family is shown with R representing the substrate. NADPH + H+ + O2 + R-H → NADP+ + H2O + R-OH In this reaction, NADPH functions as: A. an oxidizing agent. B. a reducing agent. C. a catalyst. D. an electrophile.
the answer is B donates e-
To a first approximation, the ionization constant of H2S is: A. near zero. B. much less than 1. C. about 1. D. much more than 1.
the answer is B because H2S is a WEAK acid it has a low ionization constant whereas a STRON acid would have a large ionization constant
2 Ag(s) + H2S(aq) → Ag2S(s) + H2(g) The formation of Ag2S is an example of what kind of reaction? A. A combination reaction B. A decomposition reaction C. A single replacement reaction D. A double replacement reaction
the answer is C
Which of the following statements most accurately describes the solubility properties of fatty acid salts? A) They are soluble in polar media only. B) They are soluble in nonpolar media only. C) They can partially dissolve in both polar and nonpolar media. D) They are completely insoluble in both polar and nonpolar media.
the answer is C A fatty acid salt contains a long hydrocarbon chain, which is soluble in nonpolar solvents. The salt also contains the charged group -CO2-Na+, which is soluble in polar solvents.
Which statement correctly describes the structure of the DNA double helix? A. Nitrogenous bases pair with other bases in the same purine or pyrimidine groups. B.The two DNA strands of the double helix are oriented in the same direction. C.The amount of guanine will equal the amount of cytosine in a DNA sequence. D.Sugar-phosphate backbones form the interior of the double helix.
the answer is C A. wrong because purines always pair with pyrimidines B. wrong because they are antiparallel D. sugar-phosphate backbones form the exterior of the double helix.
What is the net charge of the peptide Arg-Ala-Phe-Leu at pH 8? A. -1 B. 0 C. +1 D. +2
the answer is C The N-terminus contributes a +1 charge along with the Arg side chain. The C-terminus contributes a -1 charge, so the net charge is +1.
At pH 7, which of the following peptides will bind to an anion-exchange column and require the lowest concentration of NaCl for elution? A. AVDEKMSTRGHKNPG B. YPGRSMHEWDIKAQP C. HIPAGEATEKALRGD D. EAPDTSEGDLIPEVS
the answer is C (HKR-ED) Only peptide C and D have a net ionic charge, BUT peptide C is less negative than D, meaning it would be easier to elude than D because it has less anions bound to the positively charged column
Which of the following atoms has the largest first ionization energy? A. Potassium B. Zinc C. Gallium D. Krypton
the answer is D ionization energy follows the same trend as electronegativity
Air is bubbled through distilled water. The solution will have a pH: A. greater than 7, because elemental nitrogen undergoes hydrolysis. B. less than 7, because elemental nitrogen undergoes hydrolysis. C. greater than 7, because carbon dioxide undergoes hydrolysis. D. less than 7, because carbon dioxide undergoes hydrolysis.
the answer is D nitrogen is INERT and does NOT react with water Carbon dioxide can undergo a hydrolysis reaction in liquid water to produce carbonic acid, a weak acid that produces a solution whose pH is less than the pH of water
Why is water in it's solid state less dense that in the liquid state?
the bent structure of the water molecule and the ratio of covalently bonded hydrogens to lone pairs on the oxygen atom maximizes the H bonding in the solid phase producing a hexagonal structure with large spaces.
Describe the anomeric carbon
the carbon atom that bears two oxygen substituents) is called the anomeric carbon.
The preferred Ion configuration of many elements on the periodic table is determined by what?
the electron configuration of the nearest noble has at 8 VALENCE electrons is the MOST stable They will lose/gain electrons until the octet rule is fulfilled and the have the same valence configuration as the noble gas.
What does a high Rf value indicate?
the highest the Rf the more NONPOLAR the compound
coordination number
the number of ions of opposite charge that surround each ion in a crystal
Hess's Law
the overall enthalpy change in a reaction is equal to the sum of enthalpy changes for the individual steps in the process
oxidation agents vs. reducing agent
the oxidation agent is whatever got REDUCED (gained H/e-) the reducing agent is whatever got OXIDIZED (gain O/loss e-/loss H)
