Microbiology - Problem Drill 01: Introduction to Microbiology No. 1 of 10 1. Microbiology is the study of all of the following except. (A) Microorganisms (B) Viruses (C) Multicellular parasites (D) Plants and animals The study of Microorganisms is included in the definition of microbiology. The study of viruses is included in the definition of microbiology. Many multicellular parasites can be seen with the aid of a microscope however some have a microscopic reproductive stage. Additionally, The study of multicellular parasites is included in the definition of microbiology. D. Correct! Plants and animals are not microorganisms and they are not included in the definition of microbiology. This is the correct answer. Define microbiology - The study of microorganisms, viruses and some multicellular parasites. When answering question that revolve around a definition eliminate choices that are not included in the definition. Do not try to make exceptions. If you find yourself pondering, It could be this if it is probably the wrong choice. (D)Plants and animals
No. 2 of 10 2. Which of the following would be an example of medical microbiology? (A) The use of bacteria to produce gasahol. (B) The use of bacteria to break down sewage. (C) The development of a vaccine for AIDS. (D) Bacteria are responsible for fixing N 2 gas into biomolecules which are then used by plants. This would be an example of biotechnology or industrial microbiology. This example can prevent diseases from spreading, however again this example does not deal with medicine directly. This would be an example of industrial microbiology. C. Correct! Since AIDS is a disease that is caused by a microorganism (HIV). This choice is in keeping with the definition of medical microbiology. This is the correct answer. Since this is an example using plants it is doubtful that it is dealing with human disease and would not be in keeping with the definition for medical microbiology. This would be an example of environmental microbiology. Define medical microbiology - The study of how microorganisms enter the body, cause disease and the search for cures through eradication or inhibition of those microorganisms. This was another definition type question. However, this question differed from the previous ones in that examples were used, which were not part of the definition. In other words you had to apply the meaning of a term to the example and see if there was a correlation. Learning vocabulary is an important component to studying microbiology. Making flash cards of new terms you encounter and reviewing them will be helpful. (C)The development of a vaccine for AIDS.
No. 3 of 10 3. Ferdinand Cohn classified bacteria on the basis of. (A) DNA sequence (B) Biochemical characteristics (C) Shape (D) Behavior DNA sequences cannot be evaluated visually, that it DNA is not visible through a microscope. Biochemical characteristics also cannot be viewed through a microscope. C. Correct! This choice conforms to Cohn s classification scheme. Shape is a characteristic that can be seen through a microscope. This would the correct choice. Behavior is not a quality that is exhibited in bacteria, rather they react to stimuli and therefore this is not a quality that is observable through a microscope. Review Cohn s classification scheme - Cohn s classification scheme is based on visual characteristics of bacteria. Bacteria are microorganisms that can only be viewed with the aid of a microscope. Note that choice D is not something that was covered in the tutorial. Very often multiple-choice questions will include a nonsense choice and very often students are tempted to put this as a correct answer, fearing that if the choice is unfamiliar to them it may stand a chance of being correct. Being familiar with the material includes not just knowing what is included in a topic but what is excluded as well. Review of your cheat sheets before an exam will help eliminate nonsense choices. Note also that during Ferdinand Cohn s lifetime DNA and Biochemical techniques had not yet been developed. Knowing the sequence of historical events would help eliminate the first two choices. (C)Shape
No. 4 of 10 4. Pasture s swan neck flask experiment disproved the theory of spontaneous generation by demonstrating that: (A) The broth in the flask stayed sterile until contaminated by organisms. (B) DNA is the genetic material. (C) The microorganisms that did grow in the flask caused diseases. (D) Boiling the broth accelerated the growth of organisms. A. Correct! According to the steps in the experiment this is true. This is the correct answer. This is true but it is irrelevant to Pasteur s experiment since it is not covered in the steps of the experiment. This is unknown but regardless of the accuracy this is also irrelevant since it is not covered in the steps of the experiment. Boiling the broth is one of the steps of the experiment but the conclusion is wrong. The reason the broth is boiled is to kill all existing microorganisms not to accelerate growth. Review Pasteur s swan neck flask experiment and his purpose for performing the experiment. Sterilize broth in a swan neck flask keep upright As long as flask is upright broth will remain sterile Tilt flask so broth comes in contact with microbes in the neck of the flask Broth becomes cloudy with growth of microbes Purpose: Disprove the theory of spontaneous generation. Note that the choices have an element of truth or plausibility yet they deviate from what the question is asking. Basically there is only one correct choice and the rest of the choices are an attempt to trick or distract you from the main point of the question. The take home message here is to keep your focus on the question. Reading the question slowly and reviewing your exam will keep you from choosing one of the trick choices. Note also, as in question number 3, that knowing the sequence of historical events can eliminate Choice B. DNA methodologies were not developed until after Pasteur s death. (A)The broth in the flask stayed sterile until contaminated by organisms.
No. 5 of 10 5. Which of the following is NOT one of Koch s postulates? (A) A microorganism that causes a disease must be found in all cases. (B) The microorganism must be isolated and purified. (C) The microorganism must be identical to an already identified organism. (D) The isolated culture should cause the same disease in a test subject. This is the first step in Koch s postulates therefore this would not be the correct answer. This is the second step in Koch s postulates therefore this would not be the correct answer. C. Correct! This is not a step in Koch s postulates and does not fulfill the purpose of Koch s postulates to determine the cause of a disease. Logically, a new disease may not yet have a causative agent ascribed to it. This is the correct choice. This is the third step in Koch s postulates therefore this would not be the correct answer. Review Koch s Postulates and the purpose of the method A microorganism that causes a disease must be found in all cases. The microorganism must be isolated and purified. The isolated culture should cause the same disease in a test subject. The microorganism should be recoverable from the test subject. Purpose: to determine the cause of a disease While this question is straight forward, this type of question can be tricky. Many students can become confused (especially if rushing through a test) and pick a choice because it is a true statement. But remember that the question is asking which one is not postulate? Again as before keep your focus on the question. Reading the question slowly and reviewing your exam will keep you from reacting and choosing a correct statement but a wrong choice. (C) The microorganism must be identical to an already identified organism.
No. 6 of 10 6. People on a cruise ship all develop the same symptoms of dysentery. The cruise doctor isolates a microorganism common to all patients that have the same symptoms. He infects a test organism with this microorganism and the test organism develops the same symptoms. He then isolates the original microorganism from the test organism. He concludes: (A) The occurrence of the same microorganism in the patients and the test organism is sheer coincidence. (B) The test organism caused the disease. (C) The microorganism could not have caused the disease because he has never seen it before. (D) The microorganism is the cause of the dysentery among the cruise ship passengers. The doctor followed Koch s postulates to determine the cause of the dysentery. He obtained a positive result when he introduced the microorganism into the test organism and again when he was able to recover the same microorganism. He can safely rule out coincidence in this case. This is a nonsense choice (See question 3) the test organism would not have been introduced into the situation till after the fact. Avoid choosing nonsense choices by taking the time to read the question and each choice thoroughly. Knowledge of a microorganism or previous identification is not one of the requirements of Koch s postulates. As in question 5, logically, a new disease may not yet have a causative agent ascribed to it. D. Correct! The doctor applied Koch s postulate to the situation in a stepwise manner to determine the cause of the dysentery. This is the correct conclusion according to Koch s postulates. This question is testing your knowledge of Koch s postulates. Note that it is not asking you to regurgitate the material as in the previous question but to apply what you know about Koch s postulates to a real life situation. It is therefore not sufficient to memorize the steps in a process but top know how each step can be applied to a situation. It is also necessary to know the purpose behind the process. (D)The microorganism is the cause of the dysentery among the cruise ship passengers.
No. 7 of 10 7. What enters a bacterium during a bacteriophage infection? (A) Radioactivity (B) Protein (C) DNA/RNA (D) The bacteriophage itself Radioactivity is not normally introduced into a bacterium when it is infected with a bacteriophage. Radioactively labeled molecules were used as a tool to demonstrate what does enter a bacterium when it is being infected by a bacteriophage. According to the Hershey-Chase experiment Protein does not enter a bacterium upon a bacteriophage infection. C. Correct! According to the Hershey-Chase experiment DNA (the genetic material) enters a bacterium upon infection by a bacteriophage infection. Bacteriophages don t normally enter a bacterium upon infection only genetic material. This was a fact that Hershey and Chase used to conduct their experiment and conclude what the genetic material was in a bacteriophage. In order to answer this question you must know that a bacteriophage is a virus that infects bacteria. This virus can have DNA or ssrna as its genetic material. In the Hershey-Chase experiment the bacteriophage had DNA as its genetic material. The steps in the Hershey-Chase experiment are as follows: 1. Label one group of bacteriophages with radioactive sulfur (S 35 ). Sulfur is only found in proteins. 2. Label another group of bacteriophages with radioactive Phosphorous (P 32 ). Phosphorous is only found in nucleic acids, such as DNA. 3. Allow bacteriophages to attach to bacteria. 4. At the early stages of the infection detach bacteriophages from bacteria by blending. 5. Only P 32 is found inside the bacterial cell demonstrating that DNA and not protein was the genetic material. 6. The purpose of the experiment was to determine the genetic material of the bacteriophage. This question revolves around the Hershey-Chase experiment even if it is not mentioned. Note also that it is not asking about the steps in the experiment but about the conclusion of the experiment. This question is another example of applying information that has been learned or memorized and not just recitation. (C)DNA/RNA
No. 8 of 10 8. The Hershey-Chase experiment demonstrated (A) How a bacteriophage infects a bacterium. (B) That radioactivity is bad for bacteria. (C) That DNA is the genetic material of all living organisms. (D) That DNA is the genetic material of bacteriophages. Only a portion of a bacteriophage enters a bacterial cell during an infection. This was a fact that Hershey and Chase were aware of and used to conduct their experiment and conclude what the genetic material was in a bacteriophage. This is a nonsense choice that is irrelevant to the purpose of the Hershey-Chase experiment. This statement is correct but it is not the correct answer. This is a trick choice and should be recognized as such and avoided. The Hershey-Chase experiment only dealt with determining the genetic material of bacteriophages. However this finding inspired the work of others to determine the structure of DNA which led to the conclusion that DNA was indeed the genetic material of all living organisms. D. Correct! Between Choices C and D this is the more correct answer. It limits the findings of the Hershey-Chase experiment to bacteriophages, which is the conclusion of the experiment. As in the previous question, this question is asking you apply what you know about the Hershey-Chase experiment and not about the details of the experiment itself. However in order to arrive at the correct answer it is it is necessary to the details of the experiment. It is also important not to conclude anything beyond the details. Doing this might lead a student to pick choice C opposed to choice D. (D)That DNA is the genetic material of bacteriophages.
No. 9 of 10 9. Which of the following represent the correct order of events in the history of microbiology? (A) Discovery of the microscope Theory of spontaneous generation repudiated Germ theory of Disease Development of antisepsis Development of chemotherapy Discovery of Penicillin (B) Theory of spontaneous generation repudiated - Discovery of the microscope Germ theory of Disease Development of antisepsis Development of chemotherapy Discovery of Penicillin (C) Discovery of the microscope Theory of spontaneous generation repudiated Development of antisepsis - Koch s postulates Development of chemotherapy Discovery of Penicillin (D) Discovery of the microscope Theory of spontaneous generation repudiated Germ theory of Disease Development of antisepsis Discovery of Penicillin Development of chemotherapy A. Correct! This is the correct temporal order of these historical events. Note also that these events follow a logical sequential order. That is, one event is dependent on a previous event. All developments in microbiology are dependent on the discovery of the microscope. Therefore this could not be the correct choice. Without the invention of the microscope, microorganisms would not have been observed and the repudiation of spontaneous generation of microorganisms may not have occurred when it did. In this choice the development of antisepsis is placed before Koch s postulates. Koch s postulates stem from the germ theory of disease that is, it is microorganisms that cause disease. From this it was determined that killing microorganisms could prevent disease. The concept that microorganisms can be killed specifically without doing harm to the host led to the search and discovery of chemotherapeutic agents specific molecules that would act like a magic bullet targeted to a narrow spectrum of microorganisms. This question requires that you not just know the significant historical events in microbiology but that you have an understanding of how each event is related to the next. As in some of the previous questions this question requires more than memorization and recitation It requires a student to make connections between previously learned facts. (A) Discovery of the microscope Theory of spontaneous generation repudiated Germ theory of Disease Development of antisepsis Development of chemotherapy Discovery of Penicillin
No. 10 of 10 10. In order to study and attain an understanding of Microbiology: (A) No Background material is needed. (B) Memorization is not involved. (C) Making connections between facts is not necessary. (D) None of the above It is necessary to come into a Microbiology class with a good understanding of general biology. Memorization is an important part of biology including microbiology. Be sure that you are familiar with the new terms introduced to you. Making flash cards will be helpful. As noted in some of the previous questions making connection is critical to understanding microbiology. This skill will become evident when trying to differentiate and identify bacteria. This is very much like detective work where you will be looking for clues to make identification. D. Correct! It is important to have a good background in biology, that you memorize key facts and terms and that you are able to make connections between the facts that you have memorized in order to study and attain an understanding of microbiology as a discipline. Be sure that you have a good working knowledge of basic biological concepts before attempting a study of microbiology. If you feel that you are lacking or need to brush you can study these concepts by reviewing a biology tutorial. Memorization, especially of vocabulary, will also be important as you study microbiology. Many of he cheat sheets will have the necessary terms that you will need to know. Make it a habit to review these sheets before an exam. When learning new facts and concepts always question why it is important to the big picture and try to determine what one fact has to do with another. (D)None of the above