Question

Multiple Choice. Highlight the single correct answer choice.

1. Streak plates are useful in microbiology to __________.

1. quantify the number of bacteria
2. measure turbidity
3. identify bacteria
4. determine cell shape

2. In the streak-plate technique, the intent is to isolate bacteria by dilution in theory by __________.

1. dilution on a solid surface
2. separating cells within the solid surface
3. using a pipette
4. dilution in water blanks

3. A pure culture consists of which of the following?

1. one genus of microbe
2. one species of microbe
3. similar Gram stain reactions
4. one streak
5. turbidity

4. The main advantage of a spread plate over a streak plate is that the spread plate __________.

1. requires fewer reagents
2. allows more types of microbes to be cultured
3. is much faster
4. allows for the calculation of cell numbers
5. gives isolated colonies

5. Eosin methylene blue (EMB) media are selective because of __________.

1. mannitol
2. the dyes
3. the pH
4. phenol red
5. the agar

6. Which of the following media are NOT selective or differential?

1. Nutrient agar
2. EMB media
3. MSA media
4. None of these are both selective and differential media.
5. All of these are both selective and differential media.

7. Selective media can be useful in isolating bacteria. Mannitol salt agar is selective because of its __________.

1. pH
2. mannitol
3. phenol red
4. salt content
5. sugar content

8. MSA is to mannitol as EMB is to __________.

1. methylene blue
2. eosin
3. lactose
4. phenol red
5. salt

9. An EMB differential media plate is streaked with a bacterial culture. Can you determine if it may be E. coli?

1. E. coli will have similar growth pattern as with nutrient agar.
2. Metallic green sheen on an EMB plate forms.
3. EMB is selective.
4. coli cannot grow on an EMB plate

10. Dyes such as phenol red or methylene blue are used in culture media to __________.

1. inhibit motility
2. stain microbes
3. kill bacteria
4. see microbes
5. detect pH changes due to metabolism

11. Selective media are used primarily to help isolate bacteria in the minority, whereas differential media are used to __________.

1. encourage growth of the desired bacteria
2. isolate bacteria
3. observe metabolism of the bacteria
4. stain bacteria
5. determine motility

12. The reason that Staphylococcus aureus turns yellow on MSA is that __________.

1. the microbes have fermented lactose
2. the microbes are salt-tolerant
3. the microbes have fermented mannitol
4. the microbes are resistant to eosin and methylene blue
5. the microbes are resistant to phenol red

13. If the chemical X-gal is added to nutrient agar, lactose fermenting colonies turn blue, while non-fermenting colonies appearwhite. What sort of medium is X-gal agar?

1. differential
2. general-purpose
3. selective
4. both selective and differential
5. neither selective nor differential

14. EMB is to eosin as MSA is to __________.

1. mannitol
2. salt
3. methylene blue
4. lactose
5. phenol red

15.What is the definition of selective media?

1. Selective media have a wide variety of fuel supplies available and support the growth of most types of bacteria.
2. Selective media have been supplemented with highly nutritious materials for the purpose of cultivating fastidious organisms.
3. Selective media incorporate chemical substances that inhibit the growth of one type of bacteria while permitting the growth of another.
4. Selective media incorporate chemical compounds that produce characteristic changes in the appearance of the bacterial colonies.

16. What is the definition of differential media?

1. Differential media incorporate chemical substances that inhibit the growth of one type of bacteria while permitting the growth of another.
2. Differential media have been supplemented with highly nutritious materials for the purpose of cultivating fastidious organisms.
3. Differential media incorporate chemical compounds that produce characteristic changes in the appearance of the bacterial colonies.
4. Differential media have a wide variety of fuel supplies available and support the growth of most types of bacteria.

17. What is the purpose of adding phenol red to mannitol salt agar?

1. Phenol red inhibits the growth of gram-positive organisms.
2. Phenol red permits the differentiation of bacteria based on their ability to ferment lactose.
3. Phenol red permits the differentiation of bacteria based on their ability to ferment mannitol.
4. Phenol red permits the differentiation of bacteria based on their ability to withstand high salt concentrations.

18. What is the purpose of adding eosin and methylene blue to eosin-methylene blue agar?

1. Eosin and methylene blue are present to inhibit the growth of gram-negative organisms.
2. Eosin and methylene blue are pH indicators that turn blue when lactose is fermented.
3. Eosin and methylene blue directly inhibit the growth of lactose nonfermenters.
4. Eosin and methylene blue are dyes that precipitate on the surface of acid-producing colonies of enteric lactose fermenters, creating a metallic green sheen.

Answer 1

streak plates are useful in the microbiology to determine cell shape - As streaking is done on ato Find the morphology or isolated - Colony. It is used for isolation into a pure culture from mixed population so that one type of species morphology is studied . But streakey is not helphes in quantity the number of bacteria, Cind it can't measure turbidity. It is not helpofue in identityly the bactenia also. Acconding to updated Chegg policy I only answered the first question only.