Mcqs Related to Biochemistry

Mcq’s Biochemistry Set 2 By Dr.Ravi at 8 February, 2010, 3:34 am 1) If AUU is the codon, what is the anticodon? a. AUU b. TAA c. UUA d. UAA 2) What are the regions of DNA called that code for proteins? a. introns b. codons c. anticodons d. exons 3) The end products of translation are a. polypeptides b. amino acids c. RNA d. DNA 4) Which if the following contains a code for a protein? a. mRNA b. RNA polymerase c. rRNA d. tRNA 5) Proteins synthesis consists of all the following steps except: a. translation b. transcription c. replication d. elongation ANSWERS: 1)D 2)D 3)A 4)A 5)C 1. Which if these cells produce and secrete antibodies? a) macrophages b) cytotoxic T cells c) helper T cells d) bacterial cells e) plasma cells

2. What kind of white blood cells defend against parasitic invaders? a) basophils b) monocytes c) eosinophils d) neutrophils e) histamines 3. ________ proliferate in the bone marrow and ________ mature in the thymus. a) B cells, T cells b) NK cells, T cells c) T cells, B cells d) B cells, NK cells e) NK cells, B cells 4. Histamine is secreted by ________. a) eosinophils b) monocytes c) basophils d) T lymphocytes e) B lymphocytes Answers: 1. e, 2. c, 3. a, 4. c

Mcq’s Of Biochemistry set1 By Dr.Ravi at 8 February, 2010, 3:21 am

This is the first set of mcq’s for biochemistry. All are based on protein synthesis mainly. Each set will contain 10 mcqs so have a good time at Medical World 1. Amplification of a chemical signal occurs when a. a receptor in the plasma membrane activates several G– protein molecules while a signal molecule is bound to it. b. a cAMP molecule activates one protein kinase molecule before being converted to AMP. c. phosphorylase and phosphatase activities are balanced.

d. receptor tyrosine kinases dimerize upon ligand binding. e. both a and d occur. 2. Which of the following provides the best evidence that cell–signaling pathways evolved early in the history of life? a. They are seen in “primitive” cells such as yeast. b. Yeast cells signal each other for mating. c. Signal transduction molecules found in distantly related organisms are similar. d. Signals can be sent long distances by cells. e. Most signals are received by cell surface receptors. 3. Consider this pathway: epinephrine → G–protein–linked receptor → G protein → adenylyl cyclase → cAMP. Identify the second messenger. a. cAMP b. G protein c. GTP d. adenylyl cyclase e. G–protein–linked receptor 4. Which observation suggested to Sutherland the involvement of a second messenger in epinephrine′s effect on liver cells? a. Enzymatic activity was proportional to the amount of calcium added to a cell–free extract. b. Receptor studies indicated that epinephrine was a ligand. c. Glycogen breakdown was observed only when epinephrine was administered to intact cells. d. Glycogen breakdown was observed when epinephrine and glycogen phosphorylase were combined. e. Epinephrine was known to have different effects on different types of cells. 5. Binding of a signal molecule to which type of receptor leads directly to a change in the distribution of anions and/or cations on opposite sides of the membrane? a. receptor tyrosine kinase b. G–protein–linked receptor c. phosphorylated receptor tyrosine kinase dimer d. ligand–gated ion channel e. intracellular receptor 6. Protein phosphorylation is commonly involved with all of the following except a. regulation of transcription by extracellular signal molecules. b. enzyme activation. c. activation of G–protein–linked receptors. d. activation of receptor tyrosine kinases. e. activation of protein kinase molecules.

7. Signal transduction pathways benefit cells for all of the following reasons except a. they help cells respond to signal molecules that are too large or too polar to cross the plasma membrane. b. they enable different cells to respond appropriately to the same signal. c. they help cells use up phosphate generated by ATP breakdown. d. they can amplify a signal. e. variations in the signal transduction pathways can enhance response specificity. 8. Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because a. they are species specific. b. they always lead to the same cellular response. c. they amplify the original signal manyfold. d. they counter the harmful effects of phosphatases. e. the number of molecules used is small and fixed. 9. The activation of receptor tyrosine kinases is always characterized by a. dimerization and phosphorylation. b. IP3 binding. c. a phosphorylation cascade. d. GTP hydrolysis. e. channel protein conformational change. 10. Lipid–soluble signal molecules, such as testosterone, cross the membranes of all cells but affect only target cells because a. only target cells retain the appropriate DNA segments. b. intracellular receptors are present only in target cells. c. most cells lack the Y chromosome required. d. only target cells possess the cytosolic enzymes that transduce the testosterone. e. only in target cells is testosterone able to initiate the phosphorylation cascade leading to activated transcription factor. Answers: 1. A 2. C 3. A 4. C 5. D 6. C 7. C 8. C 9. A 10. B

24 - biochemistry mcqs - 156 to 166 156. which of the following require template for its formation ? a- carbohydrate b- protein c- lipids d- phospholipids e- nucleic acids answer : b and e . proteins require the m RNA template where as the nucleic acids require the DNA template . 157. which of the following are intermediate metabolites in TCA cycle ? a- pyruvate b- malonate c- oxaloacetate d- isocitrate e- nitric oxide answers : c and d . 158. which is the smallest fundamental unit coding for DNA synthesis ? a- cistron b- operon c- replican d- anti codon answer : a . cistron . 159. metabolic bone disease is caused by excess intake of which vitamin ? a- vitamin A

b- vitamin B c- vitamin C d- vitamin D e- vitamin E answer : a and d are the answers . both vitamin D and vitamin A . 160. hypolipidemic agents act on : a- HMG COA synthetase b- HMG COA oxygenase c- HMG COA reductase d- HMG COA hydratase e- HMG COA mutase Answer : c. HMG CO A reductase . 161. correct sequence of enzymes required for DNA formation ? Answer : DNA topoisomerase – RNA polymerase – DNA polymerase 3 – DNA polymerase 1 – DNA ligase . I did not give u the options because , it would confuse u further . 162. which of the following are the bile acids synthesized in the liver ? ( primary bile acids ) a- cholic acid b- chenodeoxy cholic acid c- deoxycholic acid d- lithocholic acid e- taurocholic acid f- glycocholic acid

answer : a and b are the answers . c and d are the secondary bile acids . e and f are the bile salts . sodium taurocholate and sodium glycocholate are the bile salts formed on combining with sodium . 163. vitamin required for the conversion of hydroxy proline to proline ? a- vitamin C b- vitamin E c- pyridoxal phosphate d- biotin answer : vitamin C . 164. enzyme activity measured in beri beri is ? a- transketolase b- transaminase c- decarboxylase d- deaminases answer : a . transketolase . 165. muscle cannot make use of glycogen for energy because of deficiency of ? a- glucokinase b- phosphoglucomutase c- glucose 6 phosphatase d- muscle phosphorylase answer : c . 166. pompe’s disease is due to deficiency of which enzyme ? a- branching enzyme b- glucose 6 phosphatase

c- acid maltase deficiency d- muscle phosphorylase answer : c . acid maltase deficiency . acid maltase is otherwise called alpha glucosidase .