ANSWERS TO EXAMINATION ONE PRACTICE QUESTIONS

Which of the following organelles most closely resembles a procaryotic cell?
Explanation: Mitcochondria contain the same type of ribosomes as found in procaryotic cells, they are about the same size as procaryotic cells, and they replicate on their own using their own DNA. One hypothesis is that mitochondria at one time were primitive bacteria that have formed a permanent symbiotic relationship with eucaryotic cells.
All of the following are differences between procaryotic and eucaryotic cell types EXCEPT
Explanation: Statements a, b and c are true. Both procaryotic and eucaryotic cells possess cell membranes.
Penicillin acts by ______ .
Explanation: Penicillin inhibits the synthesis of peptidoglycan, a component of the cell wall.
The function of the cell membrane is to
Explanation: The cell membrane is selectively permeable, permitting some atoms and/or molecules to enter and inhibiting others. The cell wall is the structure that prevents bursting in dilute solutions. The ribosome is the protein factory. The chromosomes store genetic information.
True or false: Resolution(resolving power) and magnification are actually synonyms when used to describe characteristics of a microscope.
Explanation: Resolution is the minimum distance needed to distinguish two structures as separate. Magnification takes the image seen in the microscope and enlarges it. It may be an inaccurate picture, i.e. magnification may display two structures as one structure if they are below (closer than) the resolving power of that particular microscope.
To view living organisms, the microscope of choice would be
Explanation: Several of the other types of microscopes require the organism to be stained or fixed in order to be seen. Staining kills the organism.
When crystal violet, iodine, acetone, and safranin are used to stain a bacterial smear, the procedure is called
The work of Louis Pasteur is used to ________ the Theory of Spontaneous Generation.
Explanation: Sterile solutions remained sterile (clear) if put into a Pasteur flask, which allowed air to enter. Airborne microbes were trapped in the bend, never reaching the "food" to grow in the solution. If the solution were tilted and allowed to flow into the bend, the solution would become turbid, indicating growth of microbes had occurred. Thus, it appears that microorganisms can only arise from other microorganisms. This contradicts the Theory of Spontaneous Generation.
An article recently reported that a blood sample from a chimpanzee with AIDS was inoculated into another chimp to see if the second chimp would also develop AIDS. This is a step in the procedure known as __________, which is used to confirm that a particular microorganism is the causative agent of a particular disease.
Explanation: One of Koch's Postulates states that when a pure culture of the suspected pathogen is inoculated into a healthy, susceptible animal, the inoculated animal should develop the disease if it is the true pathogen for that particular disease. In this case, the virus that causes AIDS (HIV) is being inoculated into a healthy, susceptible host and the chimp is under observation for signs of developing AIDS.
In DNA, adenine always pairs with _____ for its complementary base.
Explanation: Adenine pairs up with thymine, while cytosine is complementary to guanine.
True or False: During Tyndallization, both vegetative and endospores are likely to be killed.
Explanation: During Tyndallization, endospores are given sufficient nutrients and a warm, moist environment to encourage them to germinate (become vegetative). If so, the subsequent heating would kill them. This opportunity for endospores to germinate occurs several times. This is usually enough for the endospores to all become vegetative and succumb to death by heat.
DNA is stored not only in chromosomes, it is also stored in
Explanation: Plasmids are extrachromosomal pieces of DNA.
A patient with AIDS is suspected of also having tuberculosis. If a sputum culture is taken, a _____ stain would be ordered to look for Mycobacterium tuberculosis in the sputum.
Explanation: Mycobacterium tuberculosis rarely will take up the Gram stain dyes. They are however, acid-fast. They do not produce capsules,endospores, or flagella.
A pyrimidine is actually a type of
Explanation:Purines are double-ringed nitrogen bases, while pyrimidines are nitrogen bases that contain a single ring.
Assume that a particular bacterial cell contains 22 percent salt and no other solutes. If it falls into a solution of salt water that contains 16 percent salt, what direction will water move - into or out of the cell? Defend your answer.
Explanation: Due to osmosis, water always moves from an area of higher concentration to an area of lower concentration. The amount of water would be higher in the salt water (84%) than in the cell (78%). Thus water would flow from the salt water into the cell, causing the cell to swell. Salt is too highly charged to pass through the cell membrane.
An _________ bacterium will produce more ATP's from the same amount of glucose than an ____________.
Explanation: Aerobic bacteria can send glucose through glycolysis, Kreb's Cycle, and Electron Transport Chain, netting 38 ATP's from one molecule of glucose for a procaryotic cell. Anaerobic bacteria can only gain the 2 ATP's from glycolysis, being unable to produce the enzymes needed for Kreb's and Electron Transport. Thus an aerobic bacterium gains 19 times the number of ATP's that an anaerobic bacterium gains from one molecule of glucose.
A student is performing a Gram stain technique in the laboratory. When reaching for the acetone-alcohol bottle, she inadvertently takes the water bottle and uses it instead of acetone-alcohol for the Gram stain procedure. Water does not function as a decolorizer like acetone-alcohol would have done.

a. What will be the color of the Gram-positive bacteria at the conclusion of the technique?
Explanation: The Gram-positive bacteria will be purple since they have absorbed the crystal violet dye.

b. What will be the color of the Gram-negative bacteria at the conclusion of the technique?
The Gram-negative bacteria will be purple because there was no decolorizer to remove the crystal violet from them. If the proper decolorizer had been employed, Gram-negative bacteria would be red in color.
What causes PKU?
Explanation: A person with PKU has a mutation in the gene that codes for the enzyme phenylalanine dehydroxylase. This enzyme converts the amino acid phenylalanine into the amino acid tyrosine.
How is PKU diagnosed?
Explanation: Blood obtained from a heel brick on the baby to be tested is placed on a card and mailed to the testing center. The blood is removed from the card and placed on media that lacks phenylalanine. This media has been previously inoculated with a strain of Bacillus subtilis that requires phenylalanine as a growth factor. If the growth of Bacillus is seen on the baby's blood, this indicates a high level of phenylalanine in the blood. The diagnosis of PKU is made.
A particular bacterium has the species name of aeruginosa and the genus name of pseudomonas. Write the scientific name of this organism correctly.
Explanation: Pseudomonas aeruginosa
The name of the person who discovered the existence of microorganisms is _____________.
Explanation: Anton van Leeuwenhoek
In class we discussed a recent newspaper article explaining how botulism toxin, one of the most potent poisons known, can be used to heal humans. What condition/symptoms would this toxin be used for?
Explanation: treating neurological disorders and nerve pain
The genus and species name of the bacteria that is a frequent cause of middle ear infections and meningitis in children under five years of age and is hopefully prevented with the Hib vaccine is _________ _________.
Explanation: Hemophilus influenzae type b
When Robert Koch was trying to develop a procedure for growing bacteria in pure culture, the scientific community was not aware of the existence of agar.

a. How did Koch become aware of the existence of agar?
Explanation: Fanny Hesse, the wife of Walter Hesse, who worked in Koch's lab, suggested using agar as a solidifying agent. She had used agar in making jellies.

b. For what purpose did Koch use agar?
Explanation: Agar is used to solidify media on which bacteria and fungi are grown. Liquid nutrients have agar added to them. Then when the agar is boiled, it dissolves in the liquid nutrients. As the agar cools down to 42 degrees Celsius, it solidifies.
What does Alka-Seltzer have to do with the cherry blossom trees that adorn the Tidal Basin in Washington, D.C.?
Explanation: According to MicroFocus box 1.7 in your textbook, the Japanese scientist who patented the enzyme in Alka-Seltzer donated the cherry blossom trees in D.C. The enzyme is produced by a fungus named Aspergillus.

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