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Of the following amino acids, which one is considered non-essential: | Arginine. | Histidine. | Alanine. | Chemistry | Isoleucine. | 134 | 4 | e0319c5a-3905-4c89-aa8d-2d917e5eea08 | 2022 |
The determination of creatine kinase isoenzymes in plasma is of clinical utility because: | It is a trimeric enzyme with non-specific tissue or organ distribution. | It's a dimeric enzyme with non-specific tissue or organ distribution. | It is a trimeric enzyme with specific tissue or organ distribution. | Chemistry | It is a dimeric enzyme with specific tissue and organ distribution. | 135 | 3 | 3e97348e-fe0b-40d5-bec3-54dc64ef4ab5 | 2022 |
Which of these enzymatic activities limits the speed of lipogenesis?: | The acetyl-CoA carboxylase. | The malonyl transacylase. | The beta-ketoacyl synthase. | Chemistry | The enoyl reductase. | 136 | 2 | c8de56a7-fa03-42ad-bb51-92bdb6699450 | 2022 |
What is a holoenzyme? | Union of two isoenzymes with identical amino acid structure. | Catalytic entity formed by a cofactor and an apoenzyme. | An ionic prosthetic group. | Chemistry | Union of two organic cofactors. | 137 | 1 | 1732e462-d99f-4124-a4ab-1fc3f8c7266e | 2022 |
Bilirubin is a breakdown product, mainly of hemoglobin. Some of its characteristics are: | It is transported directly to the liver. | To be highly soluble in water. | It is transported to the liver associated with albumin. | Chemistry | It is transported to the liver associated with biliverdin. | 138 | 4 | afe9a29b-44cd-4c44-a20e-3eca26d0d897 | 2022 |
The integrins are: | Membrane proteins that act as mediators in cellular adhesion. | Membrane proteins involved in ion transport. | Glucose transport proteins and other monosaccharides. | Chemistry | Extracellular matrix proteins that bind to cell surface proteins. | 139 | 2 | 2159a658-6daa-40d5-9f8e-c07e91918812 | 2022 |
Hormonal stimulation of the formation of the second messenger inositol 1,4,5-triphosphate (IP3) quickly leads to release, of what other intracellular messenger? | Prostaglandin. | Cyclic AMP. | Cyclic GMP. | Chemistry | Calcium. | 140 | 3 | 9bb7f88f-fafb-49f5-aad8-a32363238ac2 | 2022 |
The translation of the nucleotide code of the mRNA into proteins is mediated by the ribosomes in the cytoplasm. Which of the following statements about this process is correct?: | The codons UAG, UGA, and UGC signal the end of a gene. | The ribosome binds to the 3' end of the mRNA to form a chemically stable environment for the rest of the molecules involved in protein synthesis. | The synthesis of proteins begins from the N-terminal end to the C-terminal end. | Chemistry | The amino acid coding sequence is read in groups of three nucleotides in the 3' to 5' direction. | 141 | 4 | 0dd86e14-e153-4af8-a1b0-f6d16c1b6d42 | 2022 |
How does the increase in temperature affect the reaction between antigen and antibody? | Decrease in reaction speed and increase in binding affinity. | Increase in reaction speed and decrease in binding affinity. | Decrease in reaction rate and decrease in binding affinity. | Chemistry | Increase in reaction speed and increase in binding affinity. | 142 | 1 | 17cccab9-7381-4de6-86b0-79b810afc7b6 | 2022 |
Ubiquinone (also called Coenzyme Q) is: | A cytochrome electron transporter in the respiratory chain. | A redox coenzyme with a heme group. | A hydrophobic quinone that transports electrons in the respiratory chain. | Chemistry | A component of the enzyme group that marks proteins for their proteolytic degradation. | 143 | 4 | fd65d3f2-d94f-440a-b999-d1853517ee84 | 2022 |
Each immunoglobulin molecule contains two light chains and two heavy chains, which can be separated by the loss of one of the following types of interactions: | Disulfide bonds. | Ionic bonds. | Van der Waals Bonds. | Chemistry | Hydrogen bonds. | 144 | 2 | 4e3bedb8-e26e-43f1-a336-0e7d92b60bff | 2022 |
Which of the following statements about the effects of an insulin increase is false?: | Activates lipogenesis. | Activates gluconeogenesis. | Promotes the uptake of glucose in peripheral tissues. | Chemistry | Activates the synthesis of glycogen. | 145 | 1 | e214d611-cf54-4b61-9701-663801ad5845 | 2022 |
An International Unit (IU) of enzyme activity is the amount of enzyme that: | Produce 1 mg of product per deciliter. | Converts 1 µmol of substrate into product per liter. | Produces 1 µmol of product per liter. | Chemistry | Converts 1 µmol of substrate into product per minute. | 146 | 3 | 504616ea-c39d-4c43-bff0-74b91e22857b | 2022 |
Which of the following statements is true only for anabolic pathways?: | They are called cycles if they regenerate an intermediate. | Their irreversible reactions (out of equilibrium) are regulated. | They are divergent and generate a variety of complex compounds. | Chemistry | They converge and generate a few simple products. | 147 | 4 | 99cdabff-ee05-4596-916c-b669c8e96a8a | 2022 |
Through what mechanism do erythrocytes generate their energy? | Oxidative phosphorylation. | Tricarboxylic acid cycle. | Transfer of electrons to oxygen. | Chemistry | Substrate-level phosphorylation. | 148 | 3 | 853a2ea4-cf0b-486c-8fbf-43cc144d097d | 2022 |
The factors or regulatory proteins of mRNA transcription in eukaryotes: | They bind to elements or trans sequences. | They bind to elements or cis sequences. | Without them, there is no transcription. | Chemistry | They activate RNA polymerase II. | 149 | 1 | edee9177-0e3d-4695-ae85-27c816a7cee7 | 2022 |
All of the following sentences correctly describe properties of proteins, except: | The solubility is maximum at the isoelectric point. | Ammonium sulfate typically precipitates proteins while preserving biological activity. | Gel chromatography separates proteins according to their size. | Chemistry | Trichloroacetic acid precipitates and denatures proteins. | 150 | 2 | 380ff9cb-36c3-420a-a462-c118ab692b99 | 2022 |
The high consumption of glucose by cancer cells is due to their greater reliance on anaerobic glycolysis than normal cells. This observation is known as: | Positive cooperative effect. | Warburg Effect. | Latent glycolysis. | Chemistry | Bohr Effect. | 151 | 1 | 42d9786c-851e-413b-8dcb-6e77cf1f14e6 | 2022 |
What is the effect of enzymes on the reactions they catalize? | Increase the speed of the reaction, only in the sense of product formation. | Increase the equilibrium constant of the reaction. | Increase the activation energy of the reaction. | Chemistry | Induce a decrease in the activation energy of the reaction. | 152 | 3 | 9b4f3d13-7b94-464b-9e7e-dfdcc982edb7 | 2022 |
Scurvy is a disease caused by a deficiency in vitamin C. The biochemical effect of this deficiency is: | A lower performance of mitochondrial electron transport, where vitamin C plays an important role. | The absence of retinal synthesis and the consequent loss of vision. | The impossibility of hydroxylation of collagen's proline to hydroxyproline, which leads to serious defects in the structure of this protein. | Chemistry | A defect in an enzyme responsible for the synthesis of fatty acids that leads to severe weight loss. | 153 | 4 | 983a72c2-c245-4546-b75f-9451c827aa79 | 2022 |
In which of the following tissues is the transport of glucose into the cell insulin-dependent?: | Cerebral. | Adipose. | Erythrocytic. | Chemistry | Hepatic. | 154 | 1 | e8334a28-5382-430a-9e92-6ce9d6906cee | 2022 |
The proofreading activity of prokaryotic DNA Polymerase I is an activity: | Transesterifier 5- 3'. | 5´-3´ Polymerase. | Exonuclease 3' -5'. | Chemistry | 5´ -3´ Exonuclease. | 155 | 4 | 7177016b-44fb-426d-bc62-16977695f335 | 2022 |
What will happen if the blood pH goes from being 7.4 to 7.2? | The hemoglobin's affinity for oxygen will decrease. | The binding of oxygen to myoglobin will be affected. | Hemoglobin will not be able to bind 2,3-bisphosphoglycerate in the central space between subunits. | Chemistry | The affinity of hemoglobin for oxygen will increase. | 156 | 2 | 21c9d918-9a54-4393-ba76-10f2050a94a1 | 2022 |
Gluconeogenesis occurs in: | Liver and adrenal cortex and, under fasting conditions, small intestine. | Only liver and adrenal cortex. | Liver and small intestine. | Chemistry | Liver and adrenal cortex and, under fasting conditions, muscle. | 157 | 2 | 57e0851a-f366-4c92-bfcf-fc830e31f824 | 2022 |
All the following amino acids contain only methyl or methylene groups as constituents of their side chains, except: | Alanine. | Leucine. | Lysine. | Chemistry | Isoleucine. | 158 | 4 | 39b86566-a776-425a-913f-8ba2ad75c6d3 | 2022 |
Which of the following statements about the pentose phosphate pathway is not true?: | All the reactions of the pathway occur in the cytoplasm. | It is a closed path, always occurring with the same sequence of reactions. | Some of the enzymes involved are not exclusive to this pathway. | Chemistry | All enzymes involved in this pathway are soluble. | 159 | 1 | ab335314-7b61-4163-b60d-029d6cae17b6 | 2022 |
Regarding the polymerase chain reaction, indicate the correct answer: | Use an equimolar mixture of ribonucleotide triphosphates (NTPs). | It is a chemical reaction, in vivo, that inhibits the synthesis of eukaryotic nucleic acids. | Does not require primers. | Chemistry | It is done through the action of a thermostable DNA polymerase. | 160 | 3 | 9ff03340-2c3a-430a-be23-2ede785c30d0 | 2022 |
Pyridine reacts with sulfur trioxide to yield: | 4-Pyridinium sulfonate. | 3-Pyridinium sulfonate. | 2-Sulfonate Pyridinium. | Chemistry | 1-Pyridinium sulfonate. | 161 | 3 | 8fb0cbd9-4145-46fb-a890-49997425ed9d | 2022 |
What is the major product obtained after heating 1-ethenyloxy-2-propene? | 4-Pentenal. | Propanol. | Pentanol. | Chemistry | Ethyl propyl ether. | 162 | 2 | ba9d9077-6fb1-42d3-b235-d465c77144b1 | 2022 |
What is it called when an optically active product is formed from an initially optically inactive substance through the use of a chiral catalyst? | Enantiospecific synthesis. | Enantioselective synthesis. | Regioselective synthesis. | Chemistry | Stereospecific synthesis. | 163 | 1 | 64d77269-8c59-42c1-8f26-686946fa0437 | 2022 |
What is the primary organic product obtained in the reaction of hexanoic acid with molecular bromine and traces of phosphorus, followed by treatment with ammonia? | 2-Bromohexamide. | Hexanoyl bromide. | 2-aminohexanoic acid. | Chemistry | 2-Bromohexanoic Acid. | 165 | 4 | 9620bce8-e016-4dcf-b2de-1bbf681b7b0a | 2022 |
Of the following methods of organic structural determination, which one is not based on the absorption of electromagnetic radiation? | Infrared. | Nuclear Magnetic Resonance. | Ultraviolet-visible. | Chemistry | Mass spectrometry. | 166 | 3 | 31324fb5-a6ea-4c3d-a368-8347d834a273 | 2022 |
Sulfides can be prepared by nucleophilic substitution (SN2) through the reaction of an alkyl halide with a: | Alkanethiolate ion. | Alcoholate ion. | Nitronium ion. | Chemistry | Sulfonium ion. | 167 | 2 | fa6c0d3d-a899-4842-b710-6f6b91085962 | 2022 |
The acidity order of phenol, cyclohexanol, benzoic acid, and 4-nitrophenol, from least to greatest, is: | Cyclohexanol < 4-Nitrophenol < Phenol < Benzoic acid. | Phenol < Cyclohexanol < 4-Nitrophenol < Benzoic acid. | Cyclohexanol < Phenol < 4-Nitrophenol < Benzoic acid. | Chemistry | Phenol < 4-Nitrophenol < Cyclohexanol < Benzoic acid. | 168 | 4 | f8f7079a-3c2f-44cd-ae70-c21db01a99bb | 2022 |
The first stage of the reaction of aldehydes and ketones with primary amines produces: | Imines. | Hemiaminals. | Pyrroles. | Chemistry | Enamines. | 169 | 1 | aba3f073-eb49-4c88-985a-4ca0880402a3 | 2022 |
What product is obtained when an alkene is treated, first, with Hg(OAc)2 in EtOH, and then, with NaBH4? | An ether. | An epoxide. | An alkane. | Chemistry | A diol. | 170 | 2 | c53a9561-ad35-443d-9633-477969747426 | 2022 |
Enols are converted into ketones through a process called: | Anomeric effect. | Hybridization. | Protonation. | Chemistry | Tautomerism. | 171 | 3 | f0925759-854a-4383-8d2b-02f9d1ecf47f | 2022 |
The only intermolecular attraction forces available between nonpolar molecules like alkanes are: | The dipole-dipole forces. | The electrostatic forces. | Induced dipole-induced dipole forces. | Chemistry | The induced dipole-dipole forces. | 172 | 4 | e739c76c-2313-4258-874e-f19026d90c54 | 2022 |
Periodic acid causes the breakage of neighboring diols to yield: | A ketone and an alcohol. | Two carbonyls. | Two alcohols. | Chemistry | An aldehyde and an alcohol. | 173 | 1 | ad1202aa-813f-4b86-968d-a428ab3ac706 | 2022 |
The stereoisomers that are not mirror images are classified as: | Diastereoisomers. | Enantiomers. | Meso forms. | Chemistry | Configurational. | 174 | 2 | b5cf1e74-259c-4052-b1f8-b68d5c6da463 | 2022 |
In the Merrifield synthesis, the polymeric support to which the peptide chain is attached is: | Polystyrene. | Polyvinyl. | Acrylonitrile. | Chemistry | Polyamide. | 176 | 2 | b98f1cc1-5268-4638-aa08-986e2533693c | 2022 |
What is the major organic product obtained in the reaction of ethyl propionate with an excess of propylmagnesium bromide followed by acid workup? | 3-Hexanone. | 4-Ethyl-4-heptanol. | Propyl propanoate. | Chemistry | Ethyl 2-bromopropanoate. | 177 | 1 | 718e4c16-1fdf-4606-8db0-6a19763db67c | 2022 |
Which of the following statements, regarding resonance structures, is true?: | The structures with the greatest charge separation are the main contributors to the resonance hybrid. | All resonance structures of a molecule must have the same energy. | All resonance structures have the same contribution to the resonance hybrid. | Chemistry | Only electrons can be delocalized. | 178 | 3 | e14e48a5-b21f-4b08-864a-a73bef664a44 | 2022 |
What major SN1 product would be obtained by treating 2-bromo-3,3-dimethylbutane with EtOH/H+? | 2-ethoxy-2,3-dimethylbutane. | 2-ethoxy-3,3-dimethylbutane. | 1-ethoxy-2,3-dimethylbutane. | Chemistry | 2-ethoxy-2,2-dimethylbutane. | 179 | 2 | 6699861f-4b3f-4ada-b30c-65632f4fd746 | 2022 |
The coupling of an organoboron with an aromatic bromide in the presence of Pd(0), is called: | Stille. | Heck. | Suzuki. | Chemistry | Negishi. | 180 | 4 | baefb3c6-dab9-4950-a083-8eeba1145d30 | 2022 |
Alkenes react with N-bromosuccinimide to form: | Vinyl Bromides. | Allylic bromides. | Alkynes. | Chemistry | Dibromides. | 181 | 1 | 54a89054-ff10-47f9-a9e7-bf04f40aa1f9 | 2022 |
What product/s would result from treating p-bromotoluene with NaNH2/NH3(liquid): | Equimolecular mixtures of p-aminotoluene and m-aminotoluene. | p-aminotoluene. | Does not react under these conditions. | Chemistry | 2-amino-4-bromotoluene. | 182 | 2 | 3ac5e780-90d8-4b9b-81dc-1ffde8abad47 | 2022 |
Which of the following alkyl halides is not suitable for preparing an amine using the Gabriel synthesis?: | 1-bromo-3-methylbutane. | 2-bromo-3-methylpentane | 1-bromo-2,3-dimethylbutane. | Chemistry | 2-bromo-2,3-dimethylbutane. | 183 | 3 | 9329ae52-2000-45fa-a570-38b5afcda361 | 2022 |
Which of the following statements is not true?: | The boiling point of chloromethane is higher than that of iodomethane. | In the electrostatic potential maps, the regions rich in electron density appear in red and the ones poor in electron density appear in blue. | The N-bromosuccinimide can be used as a source of bromine in free radical brominations. | Chemistry | The chemistry of vinyl halides is different from that of alkyl halides because their bonding and hybridization are different. | 184 | 2 | d983d006-75fc-4867-b5b1-8320d18a42b6 | 2022 |
The reaction that transforms pyridine into 2-aminopyridine by treatment with sodium amide in liquid ammonia is known as: | Merrifield Reaction. | Suzuki Reaction. | Chichibabin Reaction. | Chemistry | Oppenauer Reaction. | 185 | 4 | 1a8cae16-3a7c-4ba2-80ef-bf827d7f115a | 2022 |
The Friedel-Crafts acylation, followed by Clemmensen or Wolff-Kishner reduction, is a standard sequence used for: | Introduce a primary alkyl group into an aromatic ring. | Obtain aromatic ketones. | Obtain benzofurans. | Chemistry | Obtain aromatic aldehydes. | 186 | 2 | 4dbcbda4-735f-4d41-a7e1-257796b98d3e | 2022 |
Which of the following reagents should be used to prepare, with greater yield, the tBu-O-CH3 via Williamson synthesis? | tBuBr and CH3I. | CH3Br and NatBuO. | tBuOH and NaCH3O. | Chemistry | tBuBr and NaCH3O. | 187 | 1 | bd5e2250-a21c-4c27-afa3-cc786c9013c1 | 2022 |
When treating 2-pentyne with H2/Lindlar catalyst, what product/s is/are obtained? | Mixtures of cis-2-pentene and trans-2-pentene. | Pentane. | cis-2-pentene. | Chemistry | trans-2-pentene. | 188 | 4 | 32a9789d-1577-41b6-9ca9-9999551ae3a9 | 2022 |
Which of the following statements, referring to the physical properties of alkanes, is false?: | The boiling points of alkanes increase as the molecular mass increases. | For the same number of carbon atoms, a branched alkane has a lower boiling point than its linear isomer. | As they are hydrophobic, alkanes make good lubricants. | Chemistry | For the same number of carbon atoms, a branched alkane melts at a lower temperature than its linear isomer. | 189 | 3 | 73b7466a-1f0d-488d-ad9e-5149c5fd4234 | 2022 |
Ethyl acetate reacts with equimolar amounts of sodium ethoxide to yield: | Ethyl ether. | Ethyl acetoacetate. | Methyl acrylate. | Chemistry | Acetone. | 190 | 1 | 63f8daea-165a-470b-aea4-ca4baf592068 | 2022 |
Indolizidine alkaloids have a nitrogen atom in the fusion of two rings of: | 5 and 6 members. | 5 and 7 members. | 4 and 5 members. | Chemistry | 6 and 7 members. | 191 | 2 | 6d07e529-e209-4dad-8680-e4c09cc9e9c3 | 2022 |
The fusion of a benzene ring at positions 2,3 of a pyrrole generates: | An indole. | A quinoline. | An isoquinoline. | Chemistry | A benzofuran. | 192 | 2 | 42d12267-5f0d-4263-b47c-8acb39ab4df4 | 2022 |
In the reaction of a racemic mixture of a product A with an optically pure enantiomer of a product B, the following is formed: | A pair of compounds that are enantiomers. | A pair of compounds that are identical. | A pair of compounds that are constitutional isomers. | Chemistry | A pair of compounds that are diastereomers. | 193 | 3 | 09ecb676-b83a-4b92-9616-3894a123be7d | 2022 |
What reaction conditions could convert an aniline into a phenol?: | Treatment with sodium hydroxide, followed by heating in water. | Treatment with sodium nitrite in an acidic medium, followed by heating in water. | Treatment with hydrogen chloride, followed by heating in water. | Chemistry | Treatment with thionyl chloride in an acidic medium, followed by heating in water. | 194 | 1 | 45819663-a582-498c-a5da-8ce2b980e67c | 2022 |
The treatment of 2-methylindole with concentrated nitric/sulfuric acids leads to nitration in the position: | Three. | One. | Five. | Chemistry | Four. | 195 | 4 | 6f6361d9-1fd4-4936-bf0b-a54382c5c2d6 | 2022 |
What is the reason that justifies the fact that the pKa of phenol (9.9) is lower than the pKa of ethanol (15.9)? | The conjugate base of phenol has a localized charge. | The conjugate base of phenol is stabilized by resonance. | The conjugate base of ethanol has a delocalized charge. | Chemistry | The conjugate base of ethanol has a localized charge. | 196 | 1 | 0c0eacbe-fc3a-4314-93a4-238ead8fcbe5 | 2022 |
The structural units responsible for the characteristic reactions of molecules are: | The nuclei. | The atoms. | The rings. | Chemistry | Functional groups. | 197 | 3 | b41a75ac-b451-4ef6-81a9-92fcd562faa0 | 2022 |
What product/s are obtained by adding Br2/CCl4 to (E)-2-butene? | Meso-2,3-dibromobutane. | 2,3-dibromobutane (racemic mixture). | Mixtures of 2,3-dibromobutanes (meso and pair of enantiomers). | Chemistry | (E)-1-bromo-2-butene. | 198 | 2 | 1e6bc463-1e83-4105-b79e-2d99ff2f3c09 | 2022 |
The Clemmensen reduction [Zn(Hg), HCl] allows the transformation of propiophenone (Ph-CO-CH2-CH3) into:: | Ph-CHOH-CH2-CH3. | Ph-CH2-CH2-CH3. | Ph-CH=CH- CH3. | Chemistry | Ketones do not react under these conditions. | 199 | 1 | 8e5575e1-3d92-4e44-916b-4f065b4f192b | 2022 |
Which of the following statements, regarding the reactivity of alkenes, is false?: | The hydroboration-oxidation of 1-methylcyclopentene leads to trans-2-methylcyclopentanol. | The addition of bromine to cyclopentene, in tetrachloromethane, leads to trans-1,2-dibromocyclopentane. | The addition of bromine to cyclopentene, in the presence of water, leads to cis-2-bromocyclopentanol. | Chemistry | The oxymercuration-demercuration (reduction) of 1-methylcyclopentene, using methanol as a solvent, leads to 1-methylmethoxycyclopentane. | 200 | 4 | 1a876d68-e4b9-45dc-974e-3456be3b747e | 2022 |
Which of the following is a metalloenzyme that contains tungsten?: | Formylmethanofuran dehydrogenase. | Carboxypeptidase A. | Carboxypeptidase B. | Chemistry | Carbon monoxide dehydrogenase. | 201 | 2 | 5748b0f6-b2b7-4a0b-90e7-acc3dbedd78d | 2022 |
The lightest lipoproteins (density <1.00 g/cm3) are: | High-density ones (HDL). | The low-density ones (LDL). | The very low-density ones (VLDL). | Chemistry | The chylomicrons. | 202 | 3 | 2ccee6da-a693-4e28-b78c-af34c37d9855 | 2022 |
How many nitrogen atoms does an adenine molecule contain? | Four. | Five. | Six. | Chemistry | Three. | 203 | 1 | 74efd35f-d765-40d9-96c4-a9c9c3952a5a | 2022 |
In a measurement procedure, the smallest concentration of analyte that we are capable of measuring with a previously established accuracy or reliability, is referred to as: | Quantification limit. | Detection limit. | Dilution limit. | Chemistry | Measurement procedure capacity. | 205 | 2 | bf52b10f-5959-4f19-80ef-5ab4f8cf4150 | 2022 |
What is the composition of the nucleus of deuterium, an isotope of hydrogen? | Two neutrons. | Two protons. | A proton and two neutrons. | Chemistry | A proton and a neutron. | 206 | 3 | 07d58c8f-7cf4-4fc2-85a6-f0970d3b0707 | 2022 |
Rifampicin inhibits transcription in bacteria because: | It binds to the promoter sequences of transcription in the DNA. | It binds to the beta subunit of bacterial RNA polymerases, preventing the eviction of the promoter. | It intercalates into the DNA mold and prevents the elongation of transcription. | Chemistry | Destabilizes the DNA-RNA heteroduplex formed during the elongation process. | 207 | 1 | 183a9eaa-6dc1-44e9-b4fe-5cadc9e1adf1 | 2022 |
A urea solution in water, with a concentration of 0.010 molal, has a freezing point of -0.019ºC. A 0.010 molal NaCl solution will have a freezing point of: | Between 0 and -0.019ºC. | 0ºC. | Between -0.019ºC and -0.038ºC. | Chemistry | -0.019ºC. | 209 | 4 | d9c7a054-3814-4bb7-8e76-da7997866114 | 2022 |
The main source of extracellular cholesterol for human tissues is: | Low-density lipoproteins (LDL). | The very low-density lipoproteins (VLDL). | The chylomicrons. | Chemistry | High-density lipoproteins (HDL). | 210 | 2 | 5b683aee-1c3b-4ec6-8bf6-b104bba60673 | 2022 |
Form A has 24 base pairs per helical turn. | In the B form, the displacement per residue is about 3.4 A. | The structure of form B is shorter and thicker than forms A and Z. | 3. | Chemistry | The Z form consists of a right-handed double helix. | 1 | 0 | d50092cd-b772-4ca7-a17c-74062af1f76a | 2021 |
Hemolysis significantly affects the serum concentrations of different constituents. Of the following, which is the correct statement?: | The LDH and potassium increase and the sodium decreases. | Potassium increases and sodium and LDH decrease. | The LDH increases and the sodium and potassium levels decrease. | Chemistry | Sodium, LDH, and potassium levels increase. | 2 | 2 | 134bcbfa-8397-447f-a48e-87a8573929b5 | 2021 |
The majority of the reducing equivalents used for the synthesis of fatty acids are generated in: | Glycolysis. | The pentose phosphate pathway. | Gluconeogenesis. | Chemistry | The citric acid cycle. | 3 | 1 | 4fe58252-cdf4-4aff-b3a1-26520f9fe3b4 | 2021 |
If the sequence of a fragment of a DNA chain is 5'- AATGCCTACGGCTTA-3', what will be the sequence of the complementary chain?: | 5'- AATGCCTACGGCTTA- 3' | 5'- TTACGGATGCCGAAT-3' | 5'- UAAGCCGUAGGCAUU-3'. | Chemistry | 5'- TAAGCCGTAGGCATT-3'. | 4 | 3 | a94ab98d-9b20-4d26-ade9-6d30dd122dfd | 2021 |
Which enzyme does not participate in the pentose phosphate pathway? | Glucose 6-phosphate dehydrogenase. | 6-phosphogluconolactonase. | Phosphoglucose isomerase. | Chemistry | 6-phosphogluconate dehydrogenase. | 5 | 4 | abc95c48-aeb9-476d-a98e-9a4c091fe02d | 2021 |
Regarding Somatostatin, indicate the false answer: | It is a hypothalamic hormone. | It is a tetradecapeptide that inhibits the growth hormone. | It is a hormone that inhibits pancreatic insulin. | Chemistry | It is a hormone that stimulates the secretion of glucagon. | 6 | 3 | ee7d75d2-8085-473e-93a2-df442b0d404c | 2021 |
An enzyme that follows a classic Michaelis-Menten kinetics has a Vmax= 100 μM/min and a Km = 15 μM. What will be the reaction rate, V0, when [S] = 10 μM? | 50 μM/min. | 40 μM/min. | 100 μM/min. | Chemistry | 70 µM/min. | 7 | 1 | 286f23a0-b992-4713-8cf8-2e09b139ac63 | 2021 |
Which of the following statements is correct for the citric acid cycle?: | Several molecules of oxygen are used directly in the oxidation of acetyl-CoA. | It produces several ATP molecules in each turn. | The main control point of the cycle is the initial reaction of the same, inhibited by ADP. | Chemistry | Its intermediates can be replenished by anaplerotic reactions. | 8 | 3 | ce325749-7b6c-4df4-8534-1ad6b7c780eb | 2021 |
The term proteome refers to: | The post-translational modifications that proteins undergo. | The set of all protein-coding genes of an organism. | The set of proteins produced by the genome of a cell. | Chemistry | The set of proteins present in the lysosomes. | 9 | 4 | 3e724cba-92a8-4acc-a835-1145fd6fd84f | 2021 |
Trans fatty acids: | They promote an increase in the concentration of high-density lipoproteins (HDL) | They constitute the natural form of unsaturated fatty acids in animal tissues. | They are predominantly generated in partial hydrogenation industrial processes. | Chemistry | They have a melting temperature lower than their cis configuration equivalents with the same number of C atoms and unsaturations. | 10 | 4 | 90a0cae3-93a6-4464-905b-4ceb0dc4d86c | 2021 |
Which of the following options related to the bond of oxygen with hemoglobin is false?: | The Bohr effect causes a higher affinity of hemoglobin for oxygen at acidic pH values. | Carbon dioxide reduces the affinity of hemoglobin for oxygen and shifts the dissociation curve to the right. | The affinity of hemoglobin for oxygen increases as the saturation percentage does. | Chemistry | The 2,3-bisphosphoglycerate decreases the affinity of hemoglobin for oxygen. | 11 | 2 | f518684d-5261-476b-a2bc-d4a1a095c076 | 2021 |
Which of the following functional domains is not present in the structure of nuclear receptors?: | DNA binding domain. | Transmembrane domain. | Regulation domain of transcription. | Chemistry | Ligand binding domain. | 12 | 1 | 712c09be-ab9e-4b2e-b108-b3ee3a5a8fb2 | 2021 |
One of the following sentences describes the effect produced by the acidification of the blood plasma on haemoglobin: | The response of hemoglobin to the variation of partial pressure of O2 ceases to be sigmoidal. | Hemoglobin increases its affinity for O2. | The partial pressure of O2 at which hemoglobin is half-saturated (P50) increases. | Chemistry | Hemoglobin loses part of its iron (Fe2+) content. | 13 | 4 | 9bb2aee6-9732-4ab8-a0c3-31dc51d45fe1 | 2021 |
Which of the following steps in cholesterol biosynthesis is the rate limiting and the site of metabolic regulation?: | Geranyl pyrophosphate → Farnesyl pyrophosphate. | 3-Hydroxy-3-methylglutaryl CoA → Mevalonic acid. | Squalene → Lanosterol. | Chemistry | Lanosterol → Cholesterol. | 14 | 1 | 34d9f24e-b570-40c8-b844-93a809310965 | 2021 |
The aquaporins: | They form hydrophilic transmembrane channels for the passage of solutes dissolved in water. | They form hydrophilic transmembrane channels for the passage of water. | They form hydrophilic transmembrane channels for the passage of sugars. | Chemistry | They form hydrophilic transmembrane channels for the passage of monovalent ions. | 16 | 1 | c272207b-46e1-4919-b52f-6968eadfb70e | 2021 |
What is it that is actually measured to determine the absorbance of a chromogen? | The decrease in the intensity of the light that reaches the detector. | The energy of the light that reaches the detector. | The relationship between the intensity of light, reaching the detector, of the chromogen and the blank. | Chemistry | The increase in the intensity of the light that reaches the detector. | 17 | 4 | c39a16c5-3455-4549-9d14-645d79561abf | 2021 |
Which of the following statements regarding a double-helix DNA molecule is true?: | The bases are perpendicular to the axis. | All hydroxyl groups of pentoses participate in the bonds. | Each chain replicates itself. | Chemistry | Each chain is parallel. | 18 | 2 | d7be44e2-6ae9-4a59-ab42-dcda4994dbfd | 2021 |
Which of the following statements is correct for the electron transport chain?: | All complexes in the transport chain pump protons into the intermembrane space. | Electrons flow from positive reduction potentials to negative reduction potentials. | Complex IV transfers electrons from cytochrome c to oxygen. | Chemistry | Ubiquitin and cytochrome c are mobile elements that each transport a pair of electrons. | 19 | 4 | 2ec8d154-be57-4a6c-ac11-54a214e25eeb | 2021 |
How can a prozone effect be detected in an immunoturbidimetric method? | Measuring the absorbance after the concentration of the sample. | Measuring absorbance after ultrafiltration. | Measuring the absorbance after treating the sample with sodium dodecyl sulfate (SDS). | Chemistry | Measuring the absorbance after dilifying the sample. | 20 | 3 | 16872ded-a316-4fbb-9bda-d0f3fb2fd1b5 | 2021 |
The greatest buffering capacity at physiological pH would be provided by a protein with an abundance of which of the following amino acids: | Histidine. | Lysine. | Leucine. | Chemistry | Aspartic Acid. | 21 | 2 | 1c62693d-8cf2-40f8-93c3-0559de3ec5bf | 2021 |
Which of the following statements is not true about the secondary structure of DNA?: | There is always the same number of purines as there are pyrimidines. | It is always with a right turn. | The denaturation of the double strand causes an increase in absorbance at 260nm. | Chemistry | The most common conformation is in the form of BDNA. | 22 | 1 | 1ecbe2dd-9692-48af-ba50-f422bd3f3124 | 2021 |
Which of the following statements about the reverse transcriptase enzyme is correct?: | It is encoded in the genome of all viruses. | It has RNA polymerase activity. | It uses RNA as a template and retrotranscribes it to DNA. | Chemistry | It does not possess DNA polymerase activity. | 23 | 4 | 9a9875c5-55db-4403-9fc5-e49305d44a48 | 2021 |
Which of the following terms is used to describe the movement of solutes in conventional electrophoresis: | Size or mass. | Electrophoretic mobility. | Composition of amino acids. | Chemistry | Isoelectric point. | 24 | 1 | adbd4743-0b5c-4778-a3b4-05550619e946 | 2021 |
Genomic libraries or gene banks: | They provide catalogs of all protein-coding genes cloned by insertion into a cloning vector. | They provide catalogs of all the genes in an organism's genome cloned by insertion into a cloning vector. | They are collections of cataloged prokaryotic genes. | Chemistry | They are collections of genes that code for RNAs cloned by insertion into a cloning vector. | 25 | 1 | b7d6f9a3-b8fd-4130-9fc0-d4a524f08def | 2021 |
Which trace element plays an important role as a cofactor of carbonic anhydrase? | Manganese. | Selenium. | Copper. | Chemistry | Zinc. | 26 | 3 | a99611cf-4b14-4b25-a0fb-43dbe6208aea | 2021 |
Which of the following statements is correct for ATP synthase?: | The F0 subunit has half-channels that allow protons to return from the intermembrane space to the matrix. | The F1 subunit, oriented towards the intermembrane space, is capable of hydrolyzing ATP. | The F0 subunit synthesizes ATP thanks to conformational changes. | Chemistry | The F1 subunit channels the passage of protons from the intermembrane space to the matrix and synthesizes ATP. | 27 | 2 | d15f7db1-9dad-4163-adbd-cfd1bb7027ff | 2021 |
The recombinant DNA: | It is hybrid DNA obtained through homologous recombination. | It is obtained through the formation of heteroduplexes by hybridization of DNA fragments from different origins. | It is obtained using restriction endonucleases and DNA ligase. | Chemistry | It is supercoiled cellular hybrid DNA. | 28 | 4 | 8fe8a07f-68de-48b3-9509-a8519343d55f | 2021 |
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