quiz questions 1-4

Question 1

How should we view things in dark field?

Answer 1

Open the iris all the way

Question 2

When using the 40X objective on the microscopes in the lab, what is the total magnification?

Answer 2

400

Question 3

Instead of isolating Azotobacteria, aerobic nitrogen-fixing bacteria, Karen wants to isolate an anaerobic, nitrogen-fixing bacteria. How should she change the enrichment conditions?

Answer 3

Keep the bacteria in a closed container, the aerobic bacteria will use up all the oxygen then die, leaving the anaerobic bacteria.

Question 4

Which molecule can be used as a terminal electron acceptor during anaerobic respiration?

Answer 4

nitrate

Question 5

mannitol salts agar

Question 6

Endospore formation is a type of reproduction.

Answer 6

False

Question 7

A () cell undergoes sporulation to form an endospore, when conditions improve, the endospore can ()

Answer 7

1. Vegetative, 2. germinate

Question 8

No color change after adding doing the nitrate test, except when zinc is added.

Answer 8

Negative test result, micrococcus cannot break down the nitrate or do denitrification

Question 9

What is the gram morphology for staph aureus?

Answer 9

Gram positive cocci

Question 10

What characteristic of Pseudomonads are we using to enrich for them?

Answer 10

Pseudomonads can metabolize a very large range of substances, which is why we are using either acetate or arginine. They are also obligate aerobes, which is why they are being grown aerobically.

Question 11

How do purple non sulfur bacteria function?

Answer 11

Can be chemoheterotrophs and phototrophs

Question 12

colony morphology of azotobacteria?

Answer 12

slimy appearance

Question 13

The presence of what key enzyme characterizes Pseudomonads?

Answer 13

cytochrome C oxidase

Question 14

Main difference between industrial bread processing and starter culture

Answer 14

Sourdough starters contain a collection of wild yeast and bacteria present on the grains, while yeast used for industrial bread production is a monoculture of Saccharomyces cerevisiae.

Question 15

What is/are the purpose(s) of salt in sauerkraut production?

Answer 15

To inhibit the growth of microorganisms, to draw sugar containing juices out of the cabbage for fermentation

Question 16

Fungal rot on sauerkraut?

Answer 16

Leaving air pockets or bubbles in the cabbage solution, Allowing the top of the cabbage mixture to dry out

Question 17

The endospore stain is primarily an example of which type of stain?

Answer 17

specialized

Question 18

What trait(s) differentiate Acinetobacter species from Pseudomonas species?

Answer 18

they are nonmotile and oxidase negative

Question 19

describe the difference between a bacteriostatic antibiotic and a bactericidal antibiotic.

Answer 19

Bacteriostatic: Halts growth but does not kill the cell
Bactericidal: Kills the cell

Question 20

An environment with high levels of antibiotics will more likely exhibit higher numbers of antibiotic-resistant bacteria compared with an environment with low levels of antibiotics

Answer 20

true

Question 21

w two shake tubes inoculated with an obligate anaerobe would be expected to differ in patterns of growth throughout the tube if one tube was incubated under aerobic conditions and the other was incubated under completely anaerobic conditions

Answer 21

Aerobic: Small zone with no growth at the top of the tube where oxygen is present in the media, growth throughout the rest of the tube.
Anaerobic: Growth throughout the tube

Question 22

what are two reasons we use the small subunit ribosomal RNA gene to do phylogenetic studies?

Answer 22

-It exists in all living organisms
-It is large enough to contain statistically meaningful amounts of information
-It performs the same function in all organisms, so selection pressures on it should be the same in all taxa
-It contains highly conserved regions for comparing evolutionarily distant organisms and highly variable regions for comparing closely related organisms
-It is not transferred horizontally

Question 23

In our attempt to isolate Bacillus, what does streaking the isolate on milk agar test for?

Answer 23

the ability to degrade casein

Question 24

How do we successfully read the gelatin deep?

Answer 24

take out of incubation and refrigerate it

Question 25

Does pseudomonas have to produce pigment?

Answer 25

No

Question 26

Acinetobacter and Pseudomonas species are both able to respire aerobically, but Acinetobacter species are __________, so we must aerate the enrichment culture so they are not outcompeted by Pseudomonas species.

Answer 26

nonmotile

Question 27

Karen is measuring zones of inhibition for her PARE isolate, using the standard disks that measure 6 mm in diameter. She sees that the bacteria has grown right up to the edge of the ampicillin disk. What diameter zone of inhibition should she record in this case?

Answer 27

6 mm

Question 28

On our plates for the propionic acid bacteria isolation, any shiny, flat, white colonies are most likely_____ while those that are smaller, more domed, gumdrop-like, and less shiny are most likely _____.

Answer 28

1. Staph, 2.cutibacterium

Question 29

A sourdough starter culture can theoretically be maintained indefinitely with the same microbial composition.

Answer 29

yes

Question 30

What are the three steps of PCR?

Answer 30

denaturation, annealing, extension

Question 31

why we need to record the 280 nm reading for our DNA samples, even though only the 260 nm reading is used to calculate the concentration of DNA in solution.

Answer 31

The 280 nm reading allows us to calculate the 260/280 ratio, which tells us how pure our DNA extraction is.

Question 32

The lactic acid bacteria we isolated from our sauerkraut fermentations are catalase-negative anaerobes. Usually, this would suggest to us that they would be unable to grow in the presence of oxygen, but we have been incubating them under aerobic conditions in our incubator and they grow just fine. How are they able to do this?

Answer 32

Lactic Acid bacteria use peroxidase to remove hydrogen peroxide instead of catalase.