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Unformatted text preview: ©Prep101 Solutions to Biology 112 Practice Midterm 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 Answer: a) is correct because II. Is false – only gram negative bacteria have an LPS layer and IV. Is false because crosslinking peptide links different peptidoglycan strands (not phospholipids) 2. The properties of phospholipids that allow for membrane formation are: a) amphipathic b) charged c) hydrophobic d) chemotrophic e) planar Answer: a) is correct. Although phospholipids can be charged and are hydrophobic amphipathic is a better answer for both qualities of phospholipids. Chemotrophic is nonsense and phospholipids aren’t planar, they are more 3 dimensional than that. 3. Bacteria and Archaea are most similar, when compared to Eukaryotes, in: a)
RNA sequences b)
DNA sequences d)
Genome organization e)
Structure Answer: e) is correct. Recent work has shown that Archaea are actually more similar to Eukaryotes with respect to DNA sequence and genome organization. Archaea are very diverse metabolically and do not resemble either prokaryotes are eukaryotes. But Archaea were originally identified as more similar to prokaryotes based upon their structure under the microscope – because they lack a true nucleus. ©Prep101 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 Answer: c) Eukaryotes have linear chromosomes, contain mitochondria but are not unicellular and don’t always exhibit logarithmic growth. Prokaryotes have circular chromosomes, do not contain membrane bound organelles, are unicellular (for the most part) and exhibit logarithmic growth. 5. Which of the following are considered both waste products and nutrients in both heterotrophs and lithotrophs, depending on the cellular reaction? a) NO3 b) NADH c) S° d) Glucose Use the following passage to answer questions 6‐8. 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. 6. Has an outer membrane. ___A____. 7. Has a very thick peptidoglycan layer. ___B____ 8. Contains LPS or lipopolysaccharide. ____A___ ©Prep101 9) 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, 4, 1 d) 3, 1, 4, 2 e) more than one is correct Answer: c) is correct. Draw a tree to solve this problem. Organism 3 (iv) is most ancient therefore is the first in the sequence. Organism 2 is most similar to Organism 3 therefore must
be most closely related and the next to evolve. You have already narrowed down the answer to c) 10) _________ 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 Answer: d) is correct. Anabolic and catabolic pathways together constitute metabolism. 11) You have designed an experiment in which you feed glucose containing radioactive carbon molecules to cells growing rapidly in the presence of oxygen. Over time, you would find the radioactivity in a) ATP b) NADH + H` c) lactic acid d) H2O e) CO2 Answer: E. If an organism can use glucose as its energy source it is a heterotroph and in the presence of oxygen it normally undergoes cellular respiration where the complete oxidation of glucose causes the release of all carbons as CO2. ©Prep101 12) If you were to design a medium that specifically allowed growth of other lithoautotrophs except iron oxidizers what would you include? Answer: ‐ N source (ie. Ammonia), inorganic C source, S source (ie. Elemental sulfur), H source (ie. Water), P source (phosphate), O source (air). But in order to distinguish between iron oxidizers and other organisms the difference is that iron oxidizers use Fe2+ as their electron source and produce Fe3+ as waste. So we would supply the medium with Fe3+ as the trace element so iron oxidizers could not grow. 13) Consider the following growth medium dissolved in water in the presence of light and air: Glucose NH4Cl NaNO3 K3PO4 H2SO4 Trace elements and vitamins a) What nutrients can be removed and still facilitate the growth of non‐phototrophic bacteria? Answer: Light and K3PO4 because vitamins are a source of all major bioelements. b) In the presence of glucose what organisms can grow? Answer: Heterotrophs can use glucose as energy source and oxygen as TEA. Nitrogen reducers can grow using oxygen as TEA, iron oxidizers may be able to grow if Fe3+ is available in the trace elements. 14) Consider the following medium dissolved in water in the presence of light and air: Glucose NH4Cl MgSO4 K2PO4 What types of organisms can grow? Answer: ‐ Heterotrophs use an organic carbon source as their electron, carbon and energy source. Lithotrophs that use ammonia as their energy source can also grow and use oxygen as the TEA. Oxygenic phototroph could also grow. ©Prep101 15) Which of the following is found at the cytoplasmic membrane i) receptor proteins ii) mRNA iii) structural polysaccharides iv) lipopolysaccharides v) peripheral channel proteins a) i ii iv b) i iii c) i iii iv d) i ii iii iv e) i ii iv v 16) 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 Answer: c) I) lysozyme is not an antibiotic, but it is an antimicrobial agent produced by animals. Ii) peptidoglycan is not an antibiotic it is a component of cell walls. Iii) lysozyme IS a antimicrobial enzyme. Iv) Penicillin is an antibiotic but it is not made by bacteriait is made by types of fungus. Therefore only iii) is true. 17) The main cause of cell sensitivity to high temperatures and the adaptation that has resulted are: a) Proteins denature, fatty acids with longer H‐C tails a) Phospholipids dissociate, fatty acids with longer H‐C tails b) Proteins denature, proteins with more disulfide bridges c) Phospholipids dissociate, formation of covalent bonds between fatty acids and proteins ©Prep101 18) The bacterial cytoplasmic membrane 1) is the same as the Eukaryotic plasma membrane in terms of molecular structure. 2) is composed of lipid and membrane proteins which are joined to each other by non‐
covalent bonds. 3) is formed from cone‐shaped lipid molecules. 4) is similar to a vesicle in structure. Mark a) if ONE of the above statements is CORRECT. b) if TWO of the above statements are CORRECT. c) if THREE of the above statements are CORRECT. d) if ALL of the above statements are CORRECT. e) if NONE of the above statements are CORRECT. 19) In the metabolism of a heterotrophic bacterium: If a nutrient donates electrons to a TEA, then it is being used as an __________ for the purpose of synthesizing __________ . If a nutrient donates electrons to NADP+, then it is being used as an __________ for the purpose of synthesizing __________. a. electron source, ATP, energy source, NADPH b. energy source, NADPH, electron source, ATP c. electron source, NADPH, energy source, ATP d. energy source, ATP, electron source, NADPH e. NONE of the above. 20) 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 Answer: e) Both sides of the membrane are completely different in composition. Different types of phospholipids are present as well there are no carbohydrate moieties on the inner face of the membrane like there is on the outer face. A‐d) are true. ...
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