Biology 112 Practice Midterm Questions

Transcription

1 Biology 112 Practice Midterm Questions 1. Identify which statement is true or false I. Bacterial cell walls prevent osmotic lysis II. All bacterial cell walls contain an LPS layer III. In a Gram stain, Gram positive cells are purple IV. Teichoic acid acts to cross link phospholipids V. Peptidoglycan is a carbohydrate a) Statements I, III and V are true b) All statements are true c) All statements are false d) Statements I, III and IV are true e) Statement III is true 2. The properties of phospholipids that allow for membrane formation are: a) amphipathic b) charged c) hydrophobic d) chemotrophic e) planar 3. Bacteria and Archaea are most similar, when compared to Eukaryotes, in: a) RNA sequences b) Metabolism c) DNA sequences d) Genome organization e) Structure esemble either prokaryotes 4. Similarities between eukaryotes and prokaryotes are: a) Both contain linear chromosomes b) Both contain mitochondria c) Both contain ribosomes d) Both are unicellular e) Both exhibit logarithmic growth Page 1 of 5

2 5. A bacterial colony is added to 100ml of LB growth medium. After a 24hr incubation at 37 o C the density of the cell population was measured to be 5x10 9 cells/ml. Assuming that you inoculated the culture at the beginning of the log phase of population growth, approximately how many cells did the bacterial colony contain if the growth rate of the population was 0.5 hour -1? a) 1.2x10 6 b) 600 c) 1.2x10 8 d) 1.6x If viable count declines but total cell count remains constant, what phase of growth is a culture in? a) lag phase b) exponential phase c) stationary phase d) exponential decline e) all of the above f) none of the above Use the following passage to answer questions 7-9. The Gram negative and Gram positive cell walls differ by a number of characteristics. Identify which characteristic is associated with which type of cell wall. A. Gram negative. B. Gram positive. 7. Has an outer membrane.. 8. Has a very thick peptidoglycan layer. 9. Contains LPS or lipopolysaccharide. Page 2 of 5

3 10) You are comparing the similarity between 4 organisms of unknown ancestry by rrna sequencing in order to determine possible phylogenetic relationships. i) organism 1 is most different from organism 3 ii) organism 1 is more similar to organism 4 than organism 2 iii) organism 2 is most similar to organism 3 iv) organism 3 is most ancient Which of the following is a possible order of evolution? a) 2, 4, 1, 3 b) 3, 4, 2, 1 c) 3, 2, 1, 4 d) 3, 1, 4, 2 e) more than one is correct 11) pathways build complex molecules while pathways break down complex molecules". a) metabolic, catabolic b) metabolic, anabolic c) metabolic, anabolic d) anabolic, catabolic e) anabolic, metabolic 12) Which of the following is true? a) Mutations always change the phenotype but not the genotype b) Mutations always change the genotype and the phenotype c) Mutations change the genotype but not the phenotype d) Mutations always change the genotype but not the phenotype e) Mutations always change the genotype and may or may not change the phenotype 13) True or false: Mutations in the non-coding regions of genes will have no effect on the proteins produced because, by definition, the non-coding regions of genes do not make up part of the protein itself. Page 3 of 5

4 14) Why do bacteriophages, transposable elements and plasmids often confer advantageous traits to bacteria? 15) Which statement about viruses is NOT correct? a) Viruses require host cell proteins for replication. b) Viral genomes contain overlapping transcriptional units. c) Some viral genomes are made of DNA-RNA hybrids. d) Some viral genomes are made of single-stranded RNA. 16) Conjugation is a process by which a) vesicles join the plasma membrane b) chromosomes are held together during mitosis c) bacteria transfer plasmids from male to a female cell d) ribosomes move along the mrna e) the original endosymbiont was engulfed by a primitive eukaryote 17) Which of the following statements is false i) lysozyme is an antibiotic made by animals ii) Peptidoglycan is an antibiotic made by some bacteria iii) lysozyme is an antimicrobial enzyme made by animals iv) penicillin is an antibiotic made by some bacteria a) 1 statement is false b) 2 statements are false c) 3 statements are false d) all statements are false e) no statements are false Page 4 of 5

5 18) Which of the following statements concerning the organization of prokaryotic genes are NOT correct? 1. Most prokaryotic genes contain spacer DNA that must be removed by splicing. 2. All the nucleotides 5' of the +1 position are called upstream nucleotides and are not transcribed. 3. Cis-acting elements code for proteins that regulate the transcription of genes on the same chromosomes. 4. The number of Shine-Dalgarno sequences on a polycistronic mrna usually are correlated with the number of ORFs. 5. The ORFs of polycistronic mrnas are all translated by the same ribosome. a) 1,2, 3 b) 1, 3, 4 c) 1, 3, 5 d) 2, 3, 4 e) 3, 4, 5 19) Transcribe and translate the following sequence. Promoter is to the right of the sequence and use the codon table provided (page 143) (Note: you do not need to outline the steps of transcription or translation). 3 ATG GTA CCC ATG CGA CAT GTA 5 5 TAC CAT GGG TAC GCT GTA CAT 3 20) How does a cell control the level of gene expression? a) Degradation of the mrna transcript using DNAses b) Promoter strength dictated by binding of ribosomes c) Affinity of transcription factors for specific sequences d) Stability of mrna e) A and C f) C and D 21) All of the following statements about membrane structure and function are true except: a) diffusion, osmosis, and facilitated diffusion do not require any energy input from the cell b) voltage across the membrane depends on an unequal distribution of ions across the plasma membrane c) special membrane proteins can cotransport two solutes by coupling diffusion with active transport d) diffusion of gases is faster in air than across membranes e) both sides of a membrane are identical in structure and function Page 5 of 5