Biology
Which plant tissue is responsible for transporting sugars and other organic nutrients from sources, such as leaves, to other parts of the plant?
What is phloem?
Which element has the greatest first ionization energy: Na, Mg, Al, or Si?
What is silicon (Si)?
Which compound is more acidic, phenol or ethanol, and what property explains the difference?
What is phenol, due to resonance stabilization of its conjugate base?
A solution contains 40% alcohol. How many milliliters of water must be added to 100 mL of the solution to reduce its concentration to 25%?
What is 60 mL?
An enzyme's reaction rate increases with substrate concentration but eventually reaches a plateau. What explains this observation?
What is enzyme saturation as the reaction approaches Vmax?
A population has a recessive allele frequency of 0.2. Assuming Hardy–Weinberg equilibrium, what percentage of the population is heterozygous?
What is 32%?
For an exothermic reaction at equilibrium, what happens to the equilibrium constant when temperature increases?
What is a decrease in the equilibrium constant?
A primary alkyl bromide reacts with NaCN in DMSO. Which reaction mechanism is favored?
What is SN2?
A bag contains 6 red balls and 4 blue balls. Two balls are drawn without replacement. What is the probability of selecting exactly one red ball?
What is 8/15?
A solution is diluted from 2.0 M to 0.5 M. If the initial volume is 100 mL, what is the final volume after dilution?
What is 400 mL?
A diploid organism has 2n = 12 chromosomes. During metaphase II of meiosis, how many chromosomes and sister chromatids are present in each cell?
What are 6 chromosomes and 12 sister chromatids?
A buffer contains a weak acid with a pKa of 4.8 and a conjugate base concentration ten times greater than the acid concentration. What is the pH?
What is 5.8?
Which reagent can convert a primary alcohol to an aldehyde without further oxidation to a carboxylic acid?
What is PCC?
A student scores 80, 85, 90, and 95 on four exams. What score must the student earn on a fifth exam to achieve an average of 90?
What is 100?
A dental clinic has a dentist-to-hygienist ratio of 3:5. If the clinic employs 24 dentists and hygienists combined, how many hygienists does it employ?
What is 15 hygienists?
During one turn of the citric acid (TCA) cycle, how many NADH, FADH₂, and GTP molecules are produced per acetyl-CoA?
What are 3 NADH, 1 FADH₂, and 1 GTP?
For the reaction 2NO2 <---> N2O4 what happens to the equilibrium position when the container volume decreases at constant temperature?
What is a shift toward N2O4?
An alkene undergoes hydroboration–oxidation using BH3 THF followed by H2O2/OH-. What are the regiochemistry and stereochemistry of the addition?
What are anti-Markovnikov regiochemistry and syn addition?
A cylindrical container has a radius of 3 cm and a height of 8 cm. If both dimensions are doubled, by what factor does the volume increase?
What is a factor of 8?
A tertiary alkyl halide reacts with a weak nucleophile in a polar protic solvent. Which substitution mechanism is favored, and what intermediate is formed?
What is SN1 via a carbocation intermediate?
Which part of the nephron becomes progressively more concentrated as water leaves the filtrate through osmosis?
What is the descending limb of the loop of Henle?
A galvanic cell has standard reduction potentials of +0.80 V for the cathode and −0.76 V for the anode. What is the standard cell potential?
What is +1.56 V?
A compound with molecular formula C4H8O produces a strong IR absorption near 1715 cm⁻¹ and gives a negative Tollens' test. What is the most likely compound?
What is 2-butanone?
Two machines can complete a task individually in 4 hours and 6 hours, respectively. If they work together at constant rates, how many hours will it take to complete the task?
What is 2.4 hours?
A competitive inhibitor is added to an enzyme-catalyzed reaction. What happens to the apparent Km and Vmax compared with the uninhibited reaction?
What is an increase in apparent Km with no change in Vmax?