Bio 1403 Practice Test 2|32 Questions with Verified Answers,100% CORRECT

Bio 1403 Practice Test 2|32 Questions with Verified Answers If two different polypeptides share the same primary structures, but have quite different tertiary structures, then this might be because A) the sequence of their amino acids is different. B) the environment in which each works may have different pH, temperature, etc. C) one, but not the other, may have been assisted by a chaperonin. D) all three of these (E) only two of these - CORRECT ANSWER e If a 50-base-pair stretch of DNA is 10% adenine (A), then what should be the proportion of guanine (G)? A) 10% (B) 20% (C) 30% (D) 40% (E) 50% - CORRECT ANSWER d If a 50-base-pair stretch of DNA is 10% adenine (A), then how many hydrogen bonds should hold the two strands together in this stretch of DNA? A) 135 (B) 140 (C) 150 (D) 155 (E) 160 - CORRECT ANSWER b How is telomerase like a ribosome? A) It catalyzes translation. (C) It is a ribozyme. (E) It consists of both RNA and protein. B) It synthesizes protein. (D) it synthesizes DNA. - CORRECT ANSWER e Which of these require(s) the process of transcription (either forward or reverse)? A) making primers (D) making primary mRNA transcripts B) making telomeres (E) all of these C) making rRNA - CORRECT ANSWER e The direct action of telomerase is to add A) DNA to the 3' overhang. (C) RNA to the 3' overhang. B) DNA to the 5' underhang. (D) RNA to the 5' underhang - CORRECT ANSWER a What do spliceosomes and ribosomes have in common? A) They contain ribozymes. (D) all three of these B) They are made of protein and RNA. (E) two of these C) They contain RNA that serves as a template for - CORRECT ANSWER e The significance of introns in eukaryotic genomes is that they are thought to allow A) for an increased frequency of crossing-over. B) for the storage of extra ribonucleotides in the cell cytoplasm. C) for a single gene to code for multiple polypeptides. D) both (A) & (B) E) both (A) & (C) - CORRECT ANSWER e Which enzyme synthesizes a different product than the others? A) telomerase (C) RNA pol (E) reverse transcriptase B) DNA pol I (D) DNA pol III - CORRECT ANSWER c How is prokaryotic transcription different from that occurring in eukaryotes? A) Eukaryotic genes cannot handle multiple RNA pols simultaneously transcribing them. B) Eukaryotic transcription can only occur during S phase. C) Eukaryotic transcription does not require RNA polymerase. D) Eukaryotic transcription requires lots of transcription factors. E) Eukaryotic transcription does not transcribe the entire transcription unit. - CORRECT ANSWER d . If a 100,000-base-pair gene is 90% intronic, then of about how many bases should the primary transcript consist, of about how many bases should the mature mRNA (excluding cap and tail) consist, and of about how many amino acids should the corresponding polypeptide consist? A) 100,000; 10,000; 3,333 (D) 50,000; 90,000; 30,000 B) 50,000; 10,000; 3,333 (E) none; 10,000; 3,333 C) 100,000; 90,000; 30,000 - CORRECT ANSWER a Circularization of eukaryotic mRNA has the same overall effect on protein synthesis as which of these other features? A) polyribosomes. B) highly effective promoters. C) multiple RNA pols transcribing the same transcription unit simultaneously. D) an abundant supply of ribonucleases. E) all except (D). - CORRECT ANSWER e Which of these is a correct sequence in which the following events occur during translation? 1. charged initiator tRNA bonds to small ribosomal subunit 2. large ribosomal subunit attaches 3. small ribosomal subunit/initiator tRNA attaches to mRNA 4. initiator tRNA departs from E site 5. next charged tRNA enters A site A) 4,1,2,3,5 (B) 1,4,5,2,3 (C) 4,1,3,2,5 (D) 1,3,2,4,5 (E) 4,1,3,5,2 - CORRECT ANSWER d Which is NOT an example of post-translational protein processing? A) removal of the signal peptide (D) splicing exons together B) removal of C peptide from pro-insulin (E) adding sugars to polypeptides C) chaperonin activity - CORRECT ANSWER d The ribosomal component that directly hydrogen-bonds with mRNA is _____, whereas the ribosomal component that directly catalyzes peptide bond formation is _____. A) rRNA of the large subunit, rRNA of the small subunit B) rRNA of the small subunit, rRNA of the large subunit C) rRNA of the small subunit, protein of the large subunit D) rRNA of the large subunit, protein of the large subunit E) protein of the small subunit, rRNA of the small subunit - CORRECT ANSWER b Spontaneous mutations are those caused by A) UV. (C) DNA pols/repair enzymes. (E) all of these. B) mutagens. (D) external factors. - CORRECT ANSWER c Theoretically, which parts of plants should be most likely to store excess calories as oil, rather than as carbohydrate, and what accounts for this? A) leaves, they make oils (D) seeds, they disperse in the environment B) roots, they store oils (E) stems, they transport oils C) flowers, are colored by oils - CORRECT ANSWER d All of these statements are true of triglycerides (TGIs), except A) polyunsaturated ones are typically solid. B) they consist of three fatty acids and a glycerol. C) they are similar to phospholipids, but in TGIs a fatty acid replaces the phosphate group. D) the lengths of their fatty acids can vary. E) they can store energy, serve as insulation, or as padding. - CORRECT ANSWER a one of the sweeteners in Truvia™, is a 4-carbon sugar alcohol with the formula C4H10O4. It is not found in stevia plants, but is produced commercially by enzymatically converting wheat starch or corn starch to glucose, which is then fermented to erythritol by food-grade yeasts, the erythritol then being separated from the fermentation broth. In humans, 90% of erythritol is absorbed by the small intestine, and remains unchanged in the bloodstream for less than 24 h, before being excreted, unchanged, by the kidneys. 19. How are sugar alcohols different from true sugars, such as glucose? Sugar alcohols A) have a higher proportion of carbon. (D) have proportionately fewer hydroxides. B) have a higher proportion of hydrogen. (E) lack double bonds. C) have a higher proportion of oxygen. - CORRECT ANSWER b one of the sweeteners in Truvia™, is a 4-carbon sugar alcohol with the formula C4H10O4. It is not found in stevia plants, but is produced commercially by enzymatically converting wheat starch or corn starch to glucose, which is then fermented to erythritol by food-grade yeasts, the erythritol then being separated from the fermentation broth. In humans, 90% of erythritol is absorbed by the small intestine, and remains unchanged in the bloodstream for less than 24 h, before being excreted, unchanged, by the kidneys. 20. Erythritol is a byproduct of the metabolism of A) fructose. (B) galactose. (C) alpha-glucose. (D) beta-glucose. (E) two of these - CORRECT ANSWER c one of the sweeteners in Truvia™, is a 4-carbon sugar alcohol with the formula C4H10O4. It is not found in stevia plants, but is produced commercially by enzymatically converting wheat starch or corn starch to glucose, which is then fermented to erythritol by food-grade yeasts, the erythritol then being separated from the fermentation broth. In humans, 90% of erythritol is absorbed by the small intestine, and remains unchanged in the bloodstream for less than 24 h, before being excreted, unchanged, by the kidneys. 21. . Given the way that erythritol is treated within the human body, what should be true? A) Erythritol is a negligible nutritional source for bacteria in the large intestine. B) Erythritol makes a negligible contribution to human metabolism. C) Erythritol makes a negligible contribution to human growth. D) all three of these are true. E) two of these are true. - CORRECT ANSWER d If a gram of lipid contains X calories, then how many calories should be present in a gram of carbohydrates? A) 0.25X (B) 0.5X (C) X (D) 2X (E) 4X - CORRECT ANSWER b which level of protein structure is maintained by hydrogen bonds between R groups (can be more than 1) - CORRECT ANSWER tertiary and quaternary which level of protein structure is maintained by hydrogen bonds between backbone elements (can be more than 1) - CORRECT ANSWER secondary which level of protein structure is maintained by peptide bonds (can be more than 1) - CORRECT ANSWER primary which level of protein structure is maintained by electrical interactions (can be more than 1) - CORRECT ANSWER tertiary and quaternary Consider an enzyme in an aqueous environment. Which statements should be true? 1. Alpha-helices are more likely to be found in the interiors of such enzymes. 2. Their active sites should predominately feature hydrophilic R groups. 3. Their allosteric sites should predominantly feature hydrophobic R groups. 4. β pleated sheets are likely to be found on the exteriors of such enzymes. A) 1 & 2 (B) 1 & 4 (C) 2 & 3 (D) 2 & 4 (E) 3 & 4 - CORRECT ANSWER a Consider a transmembrane protein that has a receptor site for a ligand. The ligand is sometimes present on the exterior of the cell. How many of these statements should be true? 1. Alpha-helices are more likely to be found on the exteriors of such proteins, next to the fatty acid tails of neighboring phospholipids. 2. Their receptor sites should feature hydrophilic R groups. 3. Such proteins are susceptible to the phenomenon known as "saturation." 4. Charged or polar R groups of this protein are likely to predominate on the transmembrane ends of this protein, or deep within its interior. A) none (B) only one (C) two (D) three (E) all four - CORRECT ANSWER e The enzyme, sucrase, catalyzes the hydrolysis of sucrose. What prevents sucrase from also catalyzing the hydrolysis of maltose? A) Maltose is heavier than sucrose. B) Maltose has a different form of glucose than has sucrose. C) Maltose has a different shape and chemistry than has sucrose. D) Maltose is not as sweet as sucrose. E) Maltose has a higher free energy than has sucrose - CORRECT ANSWER c What is the correct chronological sequence in which the following act to determine the 3-D conformation of an enzyme? 1. Substrate 2.DNA 3.Chaperonins 4. Ribosomes A) 1,2,3,4 (B) 2,4,3,1 (C) 1,2,4,3 (D) 2,3,4,1 (E) 3,4,2,1 - CORRECT ANSWER b Which does NOT belong with the others? A) the trombone model (D) continuous DNA replication B) Okazaki fragments (E) more catalytic activity by primase, ligase, & DNA pol I C) lagging strand - CORRECT ANSWER d Watson-Crick base pairing helped to explain A) how phosphodiester bonds are catalyzed. B) the existence of "the 5' to 3' rule." C) Chargaff's rules. D) why DNA polymerases can only extend previously existing nucleotides. E) why primers consist of RNA, rather than DNA. - CORRECT ANSWER c