15 - biochemistry mcqs - 121 to 131

121) Stop Codons

a. UAG

b. UGA

c. UAA

d. All

Answer (d) All of the above

Reference: Harper 27^th Edition Page 366

122) Weakest bond

a. Vanderwalls bond

b. Covalent

c. Ionic

d. Gravitational

Answer (a) Vanderwalls bond

Reference: Harper 27^th Edition Page 7

123) All of the following are involved in various steps of Electron transport chain except:

a. NADP

b. NAD

c. Co Enzyme Q

d. CoA

Answer (a) NADP

Reference: Harper 27^th Edition Page 103

124) Consumption of Ethanol leads to increased levels of

a. Lactate

b. acetaldehye

c. NADH

d. All of the above

Answer: All of the above

Reference: Harper 27^th Edition Page 225

125) Un acceptable type of Missence Mutation is

a. Hb M

b. Hb Hikari

c. Hb S

d. None

Answer : (A) Hb M

Reference: Vasudevan 2^nd Edition Page 308

New Hb	Effect
Hb Bristol	No functional Change
Hb Sydney	No functional Change
Hb Hikari	Acceptable Mistake
Hb S	Partially Acceptable Mistake
Hb M	Unacceptable Mutations
Hb Tak	Nonsense Mutations
Hb Constant Spring	Production of “Run on Polypeptide”

126) Pentose Sugar in Nueclic acid

a. Ribose

b. Deoxyribose

c. Both

d. None

Answer (C ) Both

Reference: Chaterjee 6^th Edition Page 27 and Harper 27^th Edition Page 298

127) Vibration Property of Molecules is checked by

a. Infra red Spectroscopy

b. Electron Microscopy

c. Light Microscopy

d. None of the above

Answer: a) Infra red Spectroscopy

Reference: See Wikipedia, Infrared spectroscopy, http://en.wikipedia.org/wiki/Infrared_spectroscopy (optional description here) (as of Nov. 6, 2006, 21:27 GMT).

Infrared spectroscopy works because chemical bonds have specific frequencies at which they vibrate corresponding to energy levels. The resonant frequencies or vibrational frequencies are determined by the shape of the molecular potential energy surfaces, the masses of the atoms and, eventually by the associated vibronic coupling. In order for a vibrational mode in a molecule to be IR active, it must be associated with changes in the permanent dipole. In particular, in the Born-Oppenheimer and harmonic approximations, i.e. when the molecular Hamiltonian corresponding to the electronic ground state can be approximated by a harmonic oscillator in the neighborhood of the equilibrium molecular geometry, the resonant frequencies are determined by the normal modes corresponding to the molecular electronic ground state potential energy surface. Nevertheless, the resonant frequencies can be in a first approach related to the strength of the bond, and the mass of the atoms at either end of it. Thus, the frequency of the vibrations can be associated with a particular bond type.

Simple diatomic molecules have only one bond, which may stretch. More complex molecules may have many bonds, and vibrations can be conjugated, leading to infrared absorptions at characteristic frequencies that may be related to chemical groups. The atoms in a CH₂ group, commonly found in organic compounds can vibrate in six different ways, symmetrical and asymmetrical stretching, scissoring, rocking, wagging and twisting.

In order to measure a sample, a beam of infrared light is passed through the sample, and the amount of energy absorbed at each wavelength is recorded. This may be done by scanning through the spectrum with a monochromatic beam, which changes in wavelength over time, or by using a Fourier transform instrument to measure all wavelengths at once. From this, a transmittance or absorbance spectrum may be plotted, which shows at which wavelengths the sample absorbs the IR, and allows an interpretation of which bonds are present. This technique works almost exclusively on covalent bonds, and as such is of most use in organic chemistry. Clear spectra are obtained from samples with few IR active bonds and high levels of purity. More complex molecular structures lead to more absorption bands and more complex spectra. The technique has been used for the characterization of very complex mixtures however.

128) The investigation for Thiamine deficiency is

a. RBC Transketalose

b. Blood Sugar

c. Serum Creatinine

d. All of the above

Answer : A) RBC Transketolase

Reference: Harper 27^th Edition Page 497

129) Casals Necklace Pattern is seen in

a. Thiamine Deficiency

b. Riboflavin Deficiency

c. Niacin Deficiency

d. All of the above

Answer C) Niacin Deficiency

Reference: Achar 3^rd Edition Page 89

130) All are examples of detoxication reactions except

a. Oxidation

b. Reduction

c. Hydrolysis

d. None of the above

Answer (d)None of the above

Reference: Chaterjee 6^th Edition Page 483

131) Vitamins needed for the synthesis of Co Enzyme A

a. Pyridoxine

b. Pantothenic Acid

c. Both

d. None

Answer C) Both

Reference: Chaterjee 6^th Edition Page 167