Test 2 Practice Questions PDF

1. The main reason fluorescence is widely applied in DNA sequencing is: a. Many dyes easily bind to DNA b. Some dyes highly increase their absorption upon binding to DNA c. Some dyes highly increase their fluorescence quantum yield upon binding to DNA d. som...

1. The main reason fluorescence is widely applied in DNA sequencing is: a. Many dyes easily bind to DNA b. Some dyes highly increase their absorption upon binding to DNA c. Some dyes highly increase their fluorescence quantum yield upon binding to DNA d. some dyes strongly decrease their fluorescence signal upon binding to DNA e. None of the above 2. If the frequency for 13C in the magnetic field 4.7T is 25.2, the frequency at magnetic field 7.05T will be: a) 25.2 b) 50.4 c) 12.6 d) 37.8 e) 100.8 3. We use 13C for NMR imaging because: a) Does not naturally occur in samples b) Is not stable and we can observe its decay c) Has lower molecular mass d) Has more neutrons e) None of the above 4. In the figure on the right the higher energy state is: a) A b) B c) Both are equal d) Depends on frequency e) None of them 5. In NMR we use atoms like 19F, 13C, etc. because: a) These atoms never appear in nature b) They have different number of electrons  c) They are not stable and emit radiation d) They have one more proton as compared to natural e) They have one more neutron as compared to natural f) They have one less neutron as compared to natural g) None of the above 6. Chemical shift in NMR for different protons is due to: a. Di erent chemistry in preparation of various compounds b. Interaction with solvent c. Shielding of the magnetic field by various solvent molecules d. Shielding of the magnetic field by electrons of various surrounding groups e. Shielding of the magnetic field by protons of various surrounding groups f. None of them 7. If magnet of 3 Tesla results in EM radiation of about 300 MHz the magnet of 9 Tesla will result in radiation of: a. 300 MHz b. 150 MHz c. 600 MHz d. 900 MHz e. 750 MHz f. None of them 8. The observed chemical shift for the 5T field was 6 PPM. If we change the direction of the field to opposite (the same value) the observed shift will be: a) 3 PPM b) 1.2 PPM c) -6 PPM d) 9 PPM  e) -12 PPM f) None of the above 9. Frequencies used by medical ultrasound are: a. Below 20 kHz but above 20 Hz b. Above 20 MHz c. Below 100 kHz d. Above 100 kHz but below 20,000 kHz e. Below 20 MHz but above 15 MHz 10. Typical wavelength generated by ultrasound device is: a. ~1 m b. ~1 km c. ~1 mm d. ~1 um e. ~1 nm 11. If magnet of 4 Tesla with field directed along direction +x results in EM radiation of about 300 MHz the magnet of 8 Tesla with field directed along direction -x (opposite) will result in radiation of: a. 300 MHz b. 150 MHz c. 600 MHz d. -600 MHz d. 900 MHz e. -300 MHz f. None of them 12. The observed chemical shift for the 5T field was 6 PPM. When we double the field strength to 10T the observed shift will be: a) 3 PPM b) 1.5 PPM c) 6 PPM d) 9 PPM e) 12 PPM 13. The acoustic wave is: a. Transverse wave b. Long wavelength c. Polarized wave d. Magnetic wave e. Amplitude wavelength f. None of them 14. Speed of ultrasound wave in a tissue as compared to speed of ultrasound wave in air is: a. higher b. lower c. depends on frequency d. cannot be estimated because ultrasound do not propagate in air e. the same 15. Which is correct definition of isotopes: a) Isotopes – forms of the element whose nuclei have the di erent number of protons but same number of neutrons  b) Isotopes – forms of the element whose nuclei have the di erent number of protons and di erent number of neutrons c) Isotopes – forms of the element whose nuclei have the same number of protons and same number of neutrons d) Isotopes – forms of the element whose nuclei have the same number of protons and different number of neutrons d) non above 16. Isomers are: a. Molecules with same chemical formula but di erent spatial arrangement of atoms b. Molecules with di erent chemical formula but similar spatial arrangement of atoms c. Molecules with identical spatial arrangement of di erent atoms d. Molecules with same chemical formula but di erent isotopes of atoms e. None of them 17. If the response of NMR system results in 500 MHz frequency the corresponding wavelength in air is: a. 600 nm b. 600 um c. 600 mm d. 600 m e. 150 um f. 150 mm 18. H1-H2 coupling results in: a. In a single line in NMR b. Multiple lines in NMR c. Shift the frequency to higher values d. Shift the frequency to lower value e. None of them.  19. Emission depolarization is a result of: f. a) Molecules randomly distributed in the solvent g. b) Fast rotational mobility of molecules in the solution h. c) Photoselection by excitation light i. d) Freezing the fluorophore solution j. e) None of the above 20. Fluorescence lifetime is: a) The shortest time molecule can stay in the excited state b) The longest time molecule can stay in the excited state c) The time after initial intensity of fluorescence decreases 2 times d) The time after population of molecules in the excited state increases e times (e ~2.72). e) The time after which molecule will photo-degrade f) The time after initial intensity of fluorescence decreases 10 times g) The longest time molecule can stay in the excited state h) None of the above 21. Solvent sensitive fluorophore exhibits: a) Excitation spectrum that do not depend on observation wavelength b) Emission spectrum that depends on the fluorophore environment c) Spectrum that depends on fluorescence lifetime d) Emission spectrum that depends on the excitation. e) Emission spectrum that does not depend on observation wavelength 22. If complex of two proteins dissociate in the physiological process emission anisotropy of probe attached (fixed) to one of them will: a) Will go up b) Will go down c) Will go up or down depending on the proteins mass d) Will not change