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Biochemistry MCQ Exam 1- PMU 2nd Year

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Prof Stakonova's MCQs specifically for Biochemistry
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Question 1

Question
Which of the following amino acids have charge at ph 7.0?
Answer
  • alanine
  • arginine
  • lysine
  • cysteine
  • aspartic acid

Question 2

Question
Which of the following statements about noncompetitive inhibitors is TRUE:
Answer
  • the noncompetitive inhibitor can bind both the enzyme and the ES complex
  • the noncompetitive inhibitor decreases Vmax but does not change Km
  • the noncompetitive inhibitor binds the enzyme at site distinct from the active site
  • the noncompetitive inhibitor is it structural analog of the substrate

Question 3

Question
The consequences of folic acid deficiency is:
Answer
  • beri-beri
  • scurvy
  • pellagra
  • megaloblastic anemia

Question 4

Question
Vit. C is involved in:
Answer
  • the biosynthesis of noradrenaline and adrenaline
  • the postsynthetic modification of procollagen to collagen
  • the formation of Coenzyme A
  • the metabolism one-carbon fragments
  • the biosynthesis of bile acids

Question 5

Question
Which of the following amino-acids are sulphur-containing?
Answer
  • Histidine
  • Cysteine
  • Threonine
  • Methionine

Question 6

Question
Which of the following statements about nuclear DNA are TRUE?
Answer
  • It contains deoxyribose as pentose
  • It contains Uracil instead of Thymine
  • It is a double-stranded circular structure
  • It is double-stranded helix

Question 7

Question
Denaturation of proteins:
Answer
  • Can affect primary structure of proteins
  • Affect all the structures except the primary structure of proteins
  • Can be reversible and irreversible depending on the duration of the denaturating agent
  • Breaks down the covalent bonds within the polypeptide chain

Question 8

Question
Which of the following statements about competitive inhibitors are TRUE?
Answer
  • The competitive inhibitor can bind only with the active site of the enzyme
  • The competitive inhibitor can bind only with the ES complex
  • The competitive inhibitor can bind both with the active site of the enzyme and the ES complex
  • Vmax remains unchanged, Km rises
  • Km remains unchanged. Vmax decreases
  • The competitive inhibitor is a structural analog of the substrate

Question 9

Question
Which of the following amino acids are hydrophobic and are localized inside the globular protein molecule?
Answer
  • Lysine and Glutamate
  • Leucine and Isoleucine
  • Alanine and Valine
  • Serine and Cysteine
  • Tryptophan and Proline

Question 10

Question
Which of the following are not included in protein structures. but have important biological role?
Answer
  • Ornithine
  • β-alanine
  • Histidine
  • Homocysteine
  • Citrulline
  • Citrate

Question 11

Question
Which is the type of covalent bond between a-amino acid residues in polypeptide chain?
Answer
  • phosphoesteric bond
  • glycosidic bond
  • sulfur bridge
  • peptide bond
  • esteric bond

Question 12

Question
Polypeptide chains are consisted of:
Answer
  • α-amino acid residues
  • nucleotides
  • glycerol
  • free fatty acids
  • glucose or other monosaccharides

Question 13

Question
The collagen is:
Answer
  • fibrilar protein
  • globular protein
  • rich of Glycine residues
  • rich of Proline residues
  • rich of Glutamate and Glutamine residues

Question 14

Question
Vitamin B1:
Answer
  • Its deficiency causes pellagra
  • Its deficiency causes “beri-beri"
  • Its chemical name is riboflavin
  • Its chemical name is thiamine

Question 15

Question
Allosteric effectors:
Answer
  • Bind with the active site of the enzyme
  • Can change the total amount of the enzymes
  • Are Inducers and suppressors
  • Are activators and inhibitors
  • can cause negative or positive feedback

Question 16

Question
Km
Answer
  • is equal to (k-1+k2)/k1
  • is equal to (k1+k2)/k-1
  • Gives information for affinity between the active site of the enzyme and its substrate
  • The higher Km is, the greater affinity exists

Question 17

Question
Which of the following belong to the six classes of enzymes according to the enzyme classification:
Answer
  • hydrolases
  • transferases
  • esterases
  • oxidoreductases
  • peptidases

Question 18

Question
The consequences of niacine (Vit. PP) deficiency is
Answer
  • beri beri
  • scurvy
  • pellagra
  • rickets

Question 19

Question
Pyridoxal phosphate coenzyme is a:
Answer
  • derivative of Vit. B2
  • derivative of Vit. B3
  • derivative of Vit. B6
  • participates in oxidation and reduction
  • Participates in transfer of amine

Question 20

Question
Which of the following co-factor's participate in reactions catalyzed by oxidoreductases:
Answer
  • Biotin
  • Pyridoxal phosphate
  • NAD+
  • CoASH
  • FMN

Question 21

Question
In which enzymes participates thiamine diphosphate (TPP)- the active form of vitamin B1.
Answer
  • aminotransferases
  • decarboxylases
  • pyruvate dehydrogenase
  • α-ketoglutarate dehydrogenase
  • transketolase

Question 22

Question
What are the interactions that stabilize the tertiary and the quatemary structure of proteins:
Answer
  • hydrophobic interactions
  • hydrogen bonds
  • ion interactions
  • peptide bonds
  • disulfide bonds in oligomeric proteins

Question 23

Question
The reversible covalent Phosphorylation-dephosphorylation of the enzymes:
Answer
  • acts on the enzymes active site
  • acts on the enzymes allosteric sites
  • acts on a single enzyme
  • acts on several enzymes
  • is under direct neural and hormonal control
  • is a mechanism for quick enzyme regulation

Question 24

Question
Which is the vitamin in FMN and FAD:
Answer
  • folic acid
  • riboflavin
  • thiamin
  • biotin
  • niacin

Question 25

Question
In competitive inhibition:
Answer
  • Vmax remains unchanged, Km decreases
  • Vmax remains unchanged, Km increases
  • Vmax and Km remain unchanged
  • Vmax and Km decrease

Question 26

Question
The feedback inhibition:
Answer
  • is a mechanism of regulation of multistep metabolic pathways
  • is under direct neural and hormonal control
  • acts on early steps enzymes
  • acts on the enzymes active site

Question 27

Question
Which of the following statements about peptide bond are TRUE:
Answer
  • the peptide bonds maintain the primary structure of proteins
  • the peptide bonds maintain the secondary structure of proteins
  • the peptide bond is a non-covalent bond
  • the peptide bond has a partial double-bond character

Question 28

Question
The simultaneous increase in AST and ALT is diagnostic marker mostly for:
Answer
  • Muscle Dieseases
  • Cardiac Diseases
  • Liver Diseases
  • Brain Diseases

Question 29

Question
Vitamin C
Answer
  • It is a water-soluble vitamin
  • Its deficiency causes pellagra
  • Its deficiency causes scurvy
  • It participates as a cofactor in the posttranslational modification of collagen

Question 30

Question
Which of the following is TRUE?
Answer
  • some of proteins are enzymes
  • all of proteins are enzymes
  • some of proteins are hormones
  • all of proteins are hormone
  • some of proteins participate as transporting molecules

Question 31

Question
Nucleotides are derivatives consisted of:
Answer
  • heterocyclic ring consisted of C- and N- atoms named purine or pyrimidine monosaccaride- ribose or deoxyribose and phosphoric acid
  • heterocyclic ring consisted of C- and S- atoms, monosaccaride- an hexose and phosphoric acid
  • heterocyclic ring consisted of C- and N- atoms, named purine or pyrimidine- a disaccharide and phosphoric acid
  • heterocyclic ring consisted of C- and N- atoms named purine or pyrimidines, monosaccaride- ribose deoxyribose and nitric acid

Question 32

Question
Protein denaturation is a process that:
Answer
  • amino acids composition is changed
  • its primary structure is disrupted
  • its biological activity is lost
  • chemical and physical feature are changed
  • its conformation is disrupted
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