prompt stringlengths 55 2.11k | chosen stringlengths 4 295 | rejected stringlengths 4 284 |
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Why is chlorophyll green ?:
1. Absorbs all wavelengths of the visible spectrum.
2. Absorbs wavelengths only from the red and ultra-red parts of the spectrum (680nm, 700nm).
3. Absorbs wavelengths in the red and blue parts of the visible spectrum.
4. Absorbs wavelengths only from the blue part of the visible spectrum.
... | 3. Absorbs wavelengths in the red and blue parts of the visible spectrum. | 4. Absorbs wavelengths only from the blue part of the visible spectrum. |
Transketolase catalyzes the transformation of ribose-5-phosphate and xylulose-5-phosphate into:
1. Two molecules of ribulose-5-phosphate.
2. Sedoheptulose-7-phosphate and glyceraldehyde-3-phosphate.
3. Fructose-6-phosphate and erythrose-4-phosphate.
4. Glyceraldehyde-3-phosphate and glucose-6-phosphate.
5. 6-Phosphogl... | 2. Sedoheptulose-7-phosphate and glyceraldehyde-3-phosphate. | 1. Two molecules of ribulose-5-phosphate. |
In oxidative stress it is characteristic:
1. Decrease in the concentration of oxidized glutathione.
2. Increase in the concentration of reduced glutathione.
3. Decreased production of reactive oxygen species.
4. Increase in the production of reactive oxygen species.
5. None of the previous are true. | 4. Increase in the production of reactive oxygen species. | 2. Increase in the concentration of reduced glutathione. |
Which amino acid is a precursor of neurotransmissions such as dopamine, adrenaline and noradrenaline ?:
1. Tryptophan
2. Serina
3. Tyrosine
4. Aspartic.
5. Glutamic | 3. Tyrosine | 5. Glutamic |
Which of the following compounds acts as a reducing agent in fatty acid biosynthesis ?:
1. NADH
2. NADPH.
3. FAD +.
4. FADH.
5. NADP +. | 2. NADPH. | 5. NADP +. |
If an animal organism has deficiencies in the path of pentose phosphate:
1. There would be an excess of activity of the enzyme glutathione reductase.
2. The pentose phosphate would be integrated into the glycolytic pathway.
3. NADH would be used to replace NADPH.
4. It would stimulate the synthesis of fatty acids in a... | 5. The concentration of NADPH would decrease. | 1. There would be an excess of activity of the enzyme glutathione reductase. |
The folded sheet β:
1. It is formed by a single polypetide chain.
2. It presents a distance between adjacent amino acids of approximately 4 ångströms.
3. It is formed by the union of two or more strands by hydrogen bonds.
4. Presents the side chains of contiguous amino acids pointing to the same side.
5. They are of t... | 3. It is formed by the union of two or more strands by hydrogen bonds. | 2. It presents a distance between adjacent amino acids of approximately 4 ångströms. |
In which part of the cell is ribosomal RNA synthesized ?:
1. Nucleolus
2. Ribosomes.
3. Vacuolas
4. Golgi apparatus.
5. Endoplasmic reticulum. | 1. Nucleolus | 5. Endoplasmic reticulum. |
The arginosuccinasa:
1. In an enzyme of the citric acid cycle.
2. Converts arginine to lysine.
3. It is activated by the allosteric effector N-acetylglutamate.
4. It produces fumarate.
5. It is a glycogenic amino acid. | 4. It produces fumarate. | 1. In an enzyme of the citric acid cycle. |
In animals, where is most of the extracellular material components synthesized ?:
1. In the smooth endoplasmic reticulum.
2. In the rough endoplasmic reticulum.
3. In the extracellular layer itself.
4. In the plasma membrane.
5. In the cytoplasm of the cell. | 2. In the rough endoplasmic reticulum. | 1. In the smooth endoplasmic reticulum. |
What is the role of the helicase in replication ?:
1. Join the single-stranded DNA to prevent the double helix from forming again.
2. Catalyze the union of nucleotides.
3. Correct the errors that occur in the replication.
4. Synthesize a primer to start replication.
5. Mechanically separate the strands of double-stran... | 5. Mechanically separate the strands of double-stranded DNA. | 3. Correct the errors that occur in the replication. |
Nitric oxide:
1. It is synthesized from methionine.
2. Activates cAMP-dependent protein kinase (PKA).
3. It binds to receptors coupled to G proteins (GPCR).
4. Induces relaxation of the vascular endothelium.
5. It binds to receptors with protein tyrosine kinase (PTK) activity. | 4. Induces relaxation of the vascular endothelium. | 3. It binds to receptors coupled to G proteins (GPCR). |
The proteasome:
1. It is formed by 21 homologous subunits organized in 3 rings.
2. It is a protein complex that catalyzes the hydrolysis of ubiquitinated proteins.
3. It is found only in animal eukaryotic cells.
4. Digest acylated proteins.
5. It is activated by a drug, bertezomil, in therapy for multiple myeloma. | 2. It is a protein complex that catalyzes the hydrolysis of ubiquitinated proteins. | 3. It is found only in animal eukaryotic cells. |
Regarding telomerases, which of the following statements is not true ?:
1. They have reverse transcriptase activity.
2. They prevent shortening of telomeres.
3. Its defect promotes carcinogenesis.
4. Its activity is essential for the stability of chromosomes.
5. They are ribozymes. | 3. Its defect promotes carcinogenesis. | 5. They are ribozymes. |
A person who presents with urine a high [Urea], possibly leads a diet:
1. Very low in carbohydrates and very high in proteins.
2. Very high in fat and low in protein.
3. Balanced except in carbohydrates.
4. Moderate in carbohydrates and balanced in fats and proteins.
5. Very high in carbohydrates and very low in prote... | 1. Very low in carbohydrates and very high in proteins. | 5. Very high in carbohydrates and very low in protein. |
The urea cycle:
1. It involves the degradation of urea.
2. It was proposed by Hatch and Slack.
3. It contains a reaction that transforms citrulline into ornithine.
4. It is intimately linked to glycolysis.
5. It begins with the formation of carbamylphosphate. | 5. It begins with the formation of carbamylphosphate. | 3. It contains a reaction that transforms citrulline into ornithine. |
The speed of the electron transport chain:
1. It depends on the concentration of oxygen.
2. Increases when the concentration of ATP increases.
3. It is determined by the need for ATP.
4. It is independent of ADP phosphorylation.
5. It increases when the concentration of NADH and FADH2 rises. 6 | 3. It is determined by the need for ATP. | 2. Increases when the concentration of ATP increases. |
The restriction enzymes hydrolyze bonds:
1. Phosphodiester
2. Glucosidics
3. Peptides
4. Ionic
5. By hydrogen bridges. | 1. Phosphodiester | 5. By hydrogen bridges. |
In humans, the synthesis of aspartate from oxaloacetate is catalysed by:
1. Oxalacetate decarboxylase.
2. Aspartate synthetase.
3. Aspartate dehydrogenase.
4. Pyridoxal phosphate-dependent transaminase.
5. Oxalacetate ligase. | 4. Pyridoxal phosphate-dependent transaminase. | 1. Oxalacetate decarboxylase. |
The micro RNA (miRNA):
1. They are coding RNAs.
2. They inhibit transcription.
3. They inhibit the translation.
4. Activate transcription.
5. Activate the translation. | 3. They inhibit the translation. | 1. They are coding RNAs. |
What characteristic is not common in biological membranes ?:
1. They are fluid.
2. They are composed of lipids and proteins.
3. They are asymmetrical.
4. They are electrically polarized.
5. The various components are assembled covalently. | 5. The various components are assembled covalently. | 1. They are fluid. |
The hydrogen atoms with partial positive charge of one water molecule can interact with the oxygen atoms, with negative partial charge of another water molecule. What name does this interaction receive? :
1. Hydrophobic
2. Polar.
3. Hydrogen bridge.
4. Van der Wall.
5. Zwitterion. | 3. Hydrogen bridge. | 1. Hydrophobic |
In relation to DNA replication, the term processivity indicates:
1. Error rate of the polymerase.
2. Deletion of one or more bases in the DNA.
3. Specificity in the speed of replication.
4. The ability of the enzyme to catalyze multiple consecutive reactions without detaching from the substrate.
5. 1,2 and 3. | 4. The ability of the enzyme to catalyze multiple consecutive reactions without detaching from the substrate. | 3. Specificity in the speed of replication. |
The hepatic synthesis of methionine from homocysteine requires:
1. Methylmalonyl-CoA mutase.
2. Methylcobalamin.
3. 5'-Adenosilcobalamin.
4. Coenzyme B6.
5. Methionine adenosyl transferase. | 2. Methylcobalamin. | 3. 5'-Adenosilcobalamin. |
The hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) by phospholipase C generates the following second messengers:
1. Inositol 1,4,5-trisphosphate and triacylglycerol.
2. Inositol 1,4, 5-trisphosphate and glycerol.
3. Inositol 1,4, 5-trisphosphate and diacylglycerol.
4. Inositol 4,5-bisphosphate and diacylgl... | 3. Inositol 1,4, 5-trisphosphate and diacylglycerol. | 1. Inositol 1,4,5-trisphosphate and triacylglycerol. |
The LDL:
1. They transport cholesterol to the tissues.
2. They transport cholesterol to the liver.
3. They transport "good" cholesterol.
4. Low blood levels are associated with a lower risk of heart attack.
5. They have a high density. | 1. They transport cholesterol to the tissues. | 2. They transport cholesterol to the liver. |
What type of amino acid side chains will compete with saline ions for solvation water ?:
1. Apolares.
2. Aliphatic
3. Aromatic
4. Polar
5. Without charge. | 4. Polar | 5. Without charge. |
What is the first level of organization of DNA in chromosomes':
1. Histones.
2. Nucleosomes.
3. Sugar-phosphate chains.
4. Proteosomes
5. Nucleotides | 2. Nucleosomes. | 4. Proteosomes |
Which process is not related to a proton gradient ?:
1. Oxidative phosphorylation
2. Synthesis of NADPH.
3. Glucolysis
4. Heat production
5. Active transport. | 3. Glucolysis | 5. Active transport. |
The thromboxanes:
1. They induce platelet aggregation.
2. They inhibit platelet aggregation.
3. They act as bronchodilators in the respiratory system.
4. They are produced in the membranes of all cells.
5. They are derived from saturated fatty acids. | 1. They induce platelet aggregation. | 5. They are derived from saturated fatty acids. |
What sequence of RNA bases will be produced when the AGGCCTTTACGC DNA fragment is transcribed ?:
1. TCCGGAAATGCG.
2. AGGCCUUUACGC.
3. UGGCCUUUUGCG
4. UGGCCUUUUCGC.
5. UCCGGAAAUGCG. | 5. UCCGGAAAUGCG. | 4. UGGCCUUUUCGC. |
Chymotrypsin is a digestive enzyme with activity:
1. DNAsa.
2. Protease
3. RNAsa.
4. Lipasa
5. Glycosidase | 2. Protease | 1. DNAsa. |
Biotin is a transporter of:
1. CO2
2. Phosphoryl
3. Acilo
4. Methyl.
5. Electrons | 1. CO2 | 3. Acilo |
Intestinal absorption of carbohydrates by absorptive cells:
1. It can be carried out with monosaccharides and disaccharides.
2. Sucrose is transported by sucrase.
3. Glucose is transported by facilitated diffusion and by Na + -dependent facilitated transport.
4. The facilitated glucose transporters, which do not bind ... | 3. Glucose is transported by facilitated diffusion and by Na + -dependent facilitated transport. | 4. The facilitated glucose transporters, which do not bind Na +, are located on the luminal side of the absorptive cell. |
Ultraviolet radiation changes the structure of DNA by:
1. Rupture of phosphodiester bonds.
2. Deamination of nitrogenous bases.
3. Depurinization
4. Formation of cyclobutyl rings of pyrimidines.
5. Hydroxylation of nitrogenous bases. | 4. Formation of cyclobutyl rings of pyrimidines. | 1. Rupture of phosphodiester bonds. |
Apoptosis is:
1. The cellular senescence.
2. A form of programmed cell death.
3. Cell migration
4. A mode of cellular reprogramming.
5. The process of cell differentiation. | 2. A form of programmed cell death. | 4. A mode of cellular reprogramming. |
The mitochondrial genome:
1. It is circular.
2. It is single-strand.
3. It encodes all mitochondrial proteins.
4. It is part of the nuclear DNA.
5. None of the above. | 1. It is circular. | 2. It is single-strand. |
The lipogenesis takes place mainly in:
1. The mitochondria'.
2. The cytosol.
3. The peroxisomes.
4. The lysosomes.
5. The lipid rafts of the membranes. | 2. The cytosol. | 3. The peroxisomes. |
The non-protein molecules that bind to the protein part of the enzyme constitute the complete enzyme are called:
1. Cofactors
2. Metallic ions
3. Coenzymes.
4. Vitamins
5. Prosthetic groups. | 1. Cofactors | 3. Coenzymes. |
Form B of DNA:
1. It is formed by a double helix levorotatory with two antiparallel nucleotide chains.
2. It is wider and longer than form A.
3. It has pairs of nitrogenous bases perpendicular to the axis of the helix.
4. Corresponds to dehydrated DNA.
5. It is the minority form presented by DNA under physiological co... | 3. It has pairs of nitrogenous bases perpendicular to the axis of the helix. | 4. Corresponds to dehydrated DNA. |
Hydroxylation of Lys and Pro residues in collagen requires:
1. Vitamin B.
2. Vitamin A.
3. Vitamin D.
4. Vitamin C.
5. None of the above options. | 4. Vitamin C. | 5. None of the above options. |
All of the following is part of the nucleosides EXCEPT:
1. Phosphate group.
2. Deoxyribose
3. Ribosa.
4. Pentose
5. Pyrrhic base. | 1. Phosphate group. | 2. Deoxyribose |
All the following events occur during the formation of phosphoenolpyruvate from pyruvate EXCEPT:
1. CO2 is consumed.
2. CO2 comes out.
3. CoA is needed.
4. ATP hydrolyzes.
5. GTP is hydrolyzed. | 3. CoA is needed. | 4. ATP hydrolyzes. |
The final product of the cytosolic fatty acid synthase in humans is acid:
1. Oleic
2. Arachidonic.
3. Linoleic
4. Palmitic.
5. Palmitoleic | 4. Palmitic. | 5. Palmitoleic |
Which of the following options is NOT an effect of insulin ?:
1. Stimulates hepatic gluconeogenesis.
2. Stimulates the uptake of glucose at the level of white adipose tissue.
3. Stimulates lipogenesis at the level of white adipose tissue.
4. Stimulates glycogen genesis in skeletal muscle.
5. It stimulates glucose upta... | 1. Stimulates hepatic gluconeogenesis. | 3. Stimulates lipogenesis at the level of white adipose tissue. |
Which of the following is not a fat-soluble vitamin ?:
1. Vitamin A.
2. Vitamin C.
3. Vitamin D.
4. Vitamin E.
5. Vitamin K. | 2. Vitamin C. | 1. Vitamin A. |
About free radicals:
1. They are compounds that contain two or three unpaired electrons in an outer orbital.
2. Reactive oxygen species (ROS) in the cell are only generated enzymatically.
3. Hydrogen peroxide is the most damaging radical in the cell.
4. The hydroxyl radical originates non-enzymatically (Heber-Weiss re... | 4. The hydroxyl radical originates non-enzymatically (Heber-Weiss reaction) and damages proteins and DNA. | 2. Reactive oxygen species (ROS) in the cell are only generated enzymatically. |
Which of the following characteristics of the genetic code is NOT CORRECT ?:
1. The sequence of nitrogenous bases of a given gene has a fixed reading frame and no punctuation marks.
2. It is degenerate, because for many amino acids there is more than one codon that encodes it.
3. The degeneration of the genetic code s... | 4. It is totally universal, allowing the heterologous expression of human proteins (eg insulin) in prokaryotic organisms such as E. coli. | 1. The sequence of nitrogenous bases of a given gene has a fixed reading frame and no punctuation marks. |
Sulfonic acids are converted to sulfonyl chlorides by treatment with:
1. Methylene chloride
2. Chlorine.
3. Sodium chloride.
4. Thionyl chloride.
5. Chloroform. | 4. Thionyl chloride. | 5. Chloroform. |
The aminoacyl-tRNA synthetases:
1. In conjunction with another enzyme, they bind the amino acid to the tRNA.
2. They interact directly with free ribosomes.
3. They exist in multiple forms for each amino acid.
4. They require GTP to activate the amino acid.
5. "Recognize" specific tRNA molecules and specific amino acid... | 5. "Recognize" specific tRNA molecules and specific amino acids. | 1. In conjunction with another enzyme, they bind the amino acid to the tRNA. |
Mass spectrometry is combined with chromatography to generate a very powerful analytical tool. With regard to mass spectrometry (MS), it can be said that:
1. The electronic ionization is based on the ion-molecule reactions between the reactive gas ions and the analyte molecules.
2. The linear quadrupole mass analyzer ... | 2. The linear quadrupole mass analyzer consists of four cylinders that are placed in parallel so that they are positively and negatively charged alternately. | 5. The ionization method known as MALDI is based on the desorption of ions from a matrix in the form of a gel by rapid bombardment of supercritical gas. |
In protein biosynthesis, base pairing takes place during the translation process between:
1. RNA and DNA
2. DNA and ribosomal RNA
3. Transfer RNA and ribosomal RNA
4. The messenger RNA and the transfer RNA.
5. 18S ribosomal RNA and 5S ribosomal RNA. | 4. The messenger RNA and the transfer RNA. | 1. RNA and DNA |
The synthesis with malonic ester is an important method to prepare:
1. Ketones
2. Aldehydes.
3. Alcohols
4. Amides
5. Acids | 5. Acids | 3. Alcohols |
The analysis by potentiometric redisolution is characterized:
1. By using the square wave as an element of excitation.
2. Because the redisolution stage is carried out without agitation.
3. Because the reoxidation step is carried out by an oxidizing agent.
4. Because currents are measured in the redisolution stage.
5.... | 3. Because the reoxidation step is carried out by an oxidizing agent. | 2. Because the redisolution stage is carried out without agitation. |
After the reaction of some xenobiotics with glutathione, the final product is formed:
1. Sulfanil urea.
2. Reduced glutathione
3. Oxidized glutathione.
4. Thiosulfate.
5. Mercapturic acid. | 5. Mercapturic acid. | 1. Sulfanil urea. |
Indicate, which of the compounds listed below, has a higher acidity:
1. Acetic acid.
2. Hydrogen bromide
3. Sulfuric acid.
4. Carbonic acid.
5. Nitric acid. | 2. Hydrogen bromide | 1. Acetic acid. |
A conjugated protein is:
1. A protein that contains chemical components different from the permanently associated amino acids.
2. A protein that contains amino acids with side chains with conjugated bonds.
3. A protein that contains chemical components that make it insoluble.
4. A protein incorrectly folded.
5. A dena... | 1. A protein that contains chemical components different from the permanently associated amino acids. | 3. A protein that contains chemical components that make it insoluble. |
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