Practice Questions
Unit 1
Questions 1-9
Resveratrol is a phytoalexin and a member of the stilbene family, which is commonly found in some spermatophytes. It is produced in plants in response to stress, injury, infection or UV radiation. The food sources of the flavonoid are grapes, peanuts, wine, blueberries, bilberries, dark chocolate, and tea. The health benefits were first detailed as the “French paradox”, where in spite of a high-fat diet the French had a low incidence of coronary artery diseases.
Resveratrol exists in two isoforms, cis and trans, both of which also exist as glucosides (bound to glucose). It has been observed that the trans form of resveratrol is more potent than the cis form. The reason for higher biological activity in the trans isoform is the lower steric hindrance of substitutes. The isomerization of trans to cis occurs either at a pH greater than 11 or by solar/UV radiations. Illumination of UV light (260 nm) for 150 min leads to the conversion of 50.9% of trans-resveratrol to its cis form.
Energy (J) = Planck’s constant (6.6 x 10-34 Js-1) x Frequency (Hz)
Speed of light (3 x 108 ms-1) = Frequency (Hz) x Wavelength (m)
log (1.5) = 0.17, log (2) = 0.30, log (3) = 0.48
A. 0.8 Hz
B. 1.1 x 10-2 Hz
C. 1.9 x 10-2 Hz
D. 1.2 x 10-3 Hz
A. 4 x 10-37 J
B. 2 x 10-36 J
C. 2 x 10-35 J
D. 4 x 10-35 J
For question 3, consider the following equations relating to pH and the equilibrium constant.
A. 0.8 Hz
B. 1.1 x 10-2 Hz
C. 1.9 x 10-2 Hz
D. 1.2 x 10-3 Hz
For questions 4-5, assume that the wavelength of the illuminating light is DIRECTLY proportional to the time required for the conversion. That is, if the wavelength of illuminating light if halved, the time required to convert approximately 50% of trans-resveratrol to cis isomers is also halved.
A. 0.67 s
B. 6.67 s
C. 35 s
D. 50 s
A. 5.5 hours
B. 6.5 hours
C. 7.5 hours
D. 8.5 hours
For questions 6-7, assume that pH is INDIRECTLY proportional to the time required for the conversion. That is, if the pH is halved, the time required to convert approximately 50% of trans-resveratrol to cis isomers is doubled.
A. 1.0 x 10-5 M
B. 3.0 x 10-5 M
C. 1.0 x 10-6 M
D. 3.0 x 10-6 M
A. 185 min
B. 230 min
C. 285 min
D. 310 min
Resveratrol has gained a lot of attention for its reported anti-aging and disease-fighting powers. It is widely considered to have various beneficial pharmacological properties such as anti-inflammatory, anti-oxidative, anti-aging, anti-diabetic and neuroprotective effects; some of which are outlined in Figure 3.
A. Prolonged blood glucose levels after meals
B. Decreased insulin sensitivity
C. Increased cytokine levels
D. Decreased gluconeogenesis
A. Impairs normal pancreatic function
B. Increasesinsulin sensitivity
C. Directly impairs lipid content
D.Prevents mitochondrial b-oxidation
