MCAT Practice Exam Questions 2022

Thin layer chromatography can use silica plates which are very polar. Will polar or non polar substances have lower Rf values on this plate? - ANSWER Polar substances - they will have a higher affinity for the silica and thus will not travel as far as the non polar substances A titration of a strong acid with a strong base or vice versa has an equivalence point around what pH? - ANSWER 7 What type of bond is usually disrupted during denaturation of proteins? - ANSWER H bond Is uracil a purine or pyrimidine? - ANSWER Pyrimidine (A is a purine, so must be paired with a pyrimidine, also U replaces T, and T is a pyrimidine) Are peptide bonds highly reactive? - ANSWER NO, they are very stable (T/F): Bomb calorimetery is a good way to determine bond enthalpies within a compound. - ANSWER FALSE - would need a ton of info What is the approximate pKa of COOH, NH3+? - ANSWER 2; 9 What would happen if dideoxynucleotides were omitted from a replication mixture? - ANSWER DNA polymerase would replicate the entire copy of DNA and produce copies of all the same length - gel electrophoresis would reveal one large band Total pressure = __ + __ - ANSWER Atmospheric pressure + gauge pressure Conditions of extreme starvation result in a high level of __. - ANSWER Cortisol As non-polar protein groups cluster in water, water has a (increase/decrease) in entropy. - ANSWER Increase - more water molecules are free now that they don't have to solvate each individual molecule of protein On the lac operon, the repressor binds to the __. - ANSWER Operator - to prevent RNA polymerase from binding What charge do basic amino acids have at pH 7.4? - ANSWER + What makes group I and II introns different from non-grouped introns? - ANSWER They are SELF-SPLICING i.e. they do not have splicing proteins to help them When an action potential induces a muscle contraction, Ca2+ is released into the __. - ANSWER Cytosol (not the sarcoplasmic reticulum) Are the particles released by gamma decay charged? What does this mean for their movement in electric fields and magnetic fields? - ANSWER No - gamma decay releases photons which are uncharged; uncharged molecules do not move in electric fields or magnetic fields How do beta particles behave in electric and magnetic fields? - ANSWER Beta decay releases electrons - negatively charged particles are deflected by electric and magnetic fields Does blood flow faster through capillaries or arteries? Why? - ANSWER Blood flows faster through arteries - capillaries have a greater NET cross-sectional area Which has higher BP: systemic or pulmonary circulation? Explain why. - ANSWER Systemic has a higher BP - pulmonary circulation is shorter than systemic, which means it has less resistance (formula), and the right ventricle generates less force (to pulmonary circulation) than the left ventricle does (to systemic circulation). Since P = F/A and pulmonary has lower force and area, pressure in pulmonary must be lower than systemic. Which has a higher blood flow rate (BFR): pulmonary or systemic circulation? - ANSWER They are equal because they are connected in series How does inhalation facilitate venous flow into the right atrium? - ANSWER Because during inhalation, thoracic pressure decreases (diaphragm pushes down and expands thoracic cavity), which causes blood to flow from high to low pressure (from veins into right atrium) - this is negative pressure breathing Which way do positive charges migrate towards in an electric field: towards the anode or cathode? - ANSWER Cathode What are anomers? - ANSWER Diastereomers of cyclic sugars (the SAME sugar, i.e. dif forms of (ex) glucose) - differ configurations at the anomeric carbon (alpha (down) or beta (up) position of the OH group) Switching from one anomer to another is called (rotamutation/mutarotation). - ANSWER Mutarotation (rotamutation does not exist) Counterclockwise is (R/S) absolute configuration. - ANSWER S configuration What is the difference between d-/l- and D-/L- notation? What about +/- notation? - ANSWER Lowercase letters are for optical activity (as are + and -; + is the same as d, - is the same as l); uppercase letters are just for configuration One enantiomer is d- or D-, the other enantiomer must be l- or L- (same with R and S) Dextroamphetamine is also known as __-amphetamine. - ANSWER + or d- (because name is DEXTROamphetamine, meaning it rotates light to the right, and + and d- represent the same thing) How do you factor in the charges of ions when calculating the force between two ions? - ANSWER (Example) if calculating force between Na+ and Ca2+, multiply by 1 for Na and 2 for Ca How does velocity of a fluid change when cross-sectional area changes? - ANSWER Continuity equation - as cross-sectional area decreases, velocity increases (but VOLUME REMAINS THE SAME) A sharp peak at 1700 cm-1 on an IR spectrum indicates the presence of what functional group? - ANSWER Carbonyl As sound travels through the ear, the intensity (increases/decreases). Why? - ANSWER Increases - intensity is P/A and area decreases as go from tympanic membrane to ossicles, so intensity must increase Sound travels fastest in what phase of matter? - ANSWER Solid (because it relies on molecular collisions for propagation) The third largest wavelength of a pipe closed at one end corresponds to the (#) harmonic. - ANSWER 5; because a pipe closed at one end can only have odd-numbered wavelengths (1,3,5 - 5 is the 3rd largest) Light as a reactant indicates a (exothermic/endothermic) reaction. - ANSWER Endothermic Salt bridges prevent charge build up in (electrolytic/galvanic) cells. - ANSWER Galvanic What is a reducing sugar? - ANSWER One that contains hemiketal or hemiacetal groups - only sugars with a free carbonyl group can undergo oxidation What is Benedict's test? What does a positive test indicate? - ANSWER Tests for presence of reducing sugars; a positive test says that there is a reducing sugar (i.e. benedict's agent has been REDUCED by the reducing sugar) Explain furanose vs pyranose. - ANSWER Furanose is a 5-carbon sugar; pyranose is a 6-carbon sugar (T/F): The common ion effect affects solubility product. - ANSWER FALSE - only affects molar solubility (increases it) What is the only factor that can affect solubility product? - ANSWER Temperature (T/F): A change in phase is accompanied by a change in temperature. - ANSWER FALSE - temperature is constant during a change in phase, but temperature can change if after the change in matter, heat is still being added/removed from the system Increasing the cross-sectional area (increases/decreases) the velocity of the fluid. - ANSWER Decreases - they are inversely proportional What enzyme preferentially cleaves peptide bonds next to aromatic amino acids? - ANSWER Chymotrypsin (others do not have specific sites) An amine is an electron (donating/withdrawing) group. - ANSWER Donating - makes the molecule a weaker acid