BIOL 250 Exam 1 Test, Study Guide, and Homework Questions with Correct Answers

A pure culture A) is sterile. B) is a population of identical cells. C) is made of a precisely defined chemical medium. D) contains one microbial cell. Correct Answer B Microbial cells first evolved on Earth approximately ________ _______ years ago. A) 1.6 to 1.8 million B) 7.0 to 7.2 million C) 3.8 to 3.9 billion D) 10.5 to 11.5 billion E) None of the above Correct Answer C Predict how Pasteur's conclusions on spontaneous generation with swan flasks would have changed if he worked with and maintained the flasks in a laminar flow hood (where the air is sterile). A) Sterilization of the swan flask solutions would not have been necessary to reject spontaneous generation. If he did sterilize the flasks, the spontaneous generation hypothesis would have been supported. B) His incubation times would not have been sufficient to refute spontaneous generation. C) Pasteur's flasks never would have putrefied, and the experiment would not have refuted spontaneous generation. D) Viruses would have still been present, and his conclusion would have been unchanged. Correct Answer C Of the structures listed below, which one is found in the outer most membrane of a Gram-negative cell? A) Ribosomes B) The peptidoglycan layer C) The periplasm D) LPS (lipopolysaccharide) layer Correct Answer D Gram-positive bacteria stain _____ with a Gram stain reaction because they have a __________ peptidoglycan layer than Gram-negative bacteria. A) red / thinner B) purple/ thinner C) purple / thicker D) red / thicker Correct Answer C Which of the following statement(s) is/are correct? A) Flagella allow bacteria to glide B) Flagella allow bacteria to swim C) The directed movement of bacterial cells in response to a gradient of a chemical, is called chemotaxis D) A and C are correct E) B and C are correct Correct Answer E Electron microscopy has _________ ________ than light microscopy, because the wavelengths of electrons are much ___________ than the wavelength of visible light. A) higher resolution/smaller B) lower magnification/larger C) higher resolution/larger D) lower resolution/smaller Correct Answer A Which of the following statements are false: A) Poly-β-alkanoates (PHA) such as poly-β-hydroxybutyrate (PHB) are carbon- and energy-storing polymers that can be used to produce biodegradable plastics. B) A major function of prokaryotic gas vesicles is to confer buoyancy on cells by decreasing their density C) A major function of the cytoplasmic membrane in prokaryotes is to act as a permeability barrier. D) Scanning electron microscopy can be used to visualize the different layers of the cell membrane(s) and cell wall Correct Answer D From the standpoint of the microorganism, in glycolysis the useful product(s) are A) Anabolic intermediates B) ATP C) Fermentation products such as lactic acid and ethanol D) Both (A) and (B) E) (A), (B), and (C) Correct Answer D During respiration electrons from the __________ of substrates are used to ________ a terminal electron acceptor that is either oxygen (aerobic respiration) or some other inorganic compound (anaerobic respiration). A) reduction / oxidize B) transport / degrade C) oxidation / reduce D) none of the above Correct Answer C Which intermediate compound(s) in the citric acid cycle is/are often used for biosynthetic pathways as well as carbon catabolism?