BIO 250 Final Exam || with A+ Guaranteed Solutions.

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 answers 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 answers 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 answers 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 answers 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 answers 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,