Micro Exam 2

A growth medium that distinguishes among different groups of bacteria on the basis of their biological and growth characteristics on the medium is called a/an ___________ medium.

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Transport

Differential

Selective

Enrichment

Differential

Square planar arrangement of cells that forms when round bacteria remain attached to each other during reproduction are called…..

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Tetrads

Streptococci

Sarcinae

Staphylococci

Tetrads

The majority of nitrogen in soil and marine environments is fixed by….

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E. coli

Symbionts

Free living bacteria and archaea

Organisms living w/in bacteria

Free living bacteria and archaea

Which of the following statements about ABC transporters is not true?

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They can be used for import and export material for the cell

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They are also responsible for multi-drug resistance

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They require energy

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They are found only in prokaryotes

They are found only in prokaryotes

Calculate the number of cfu/mL for the E. Coli sample.

2\.78x10^7

The growth rate of a given species of microorganism is dependent on the composition of the medium in which it is grown.

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T/F

True

Which of the following proteins represents a coupled transport system where two molecules travel in the opposite direction?

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Symporter

Aquaporin

Efflux Pump

Antiporter

Antiporter

After you transferred 1mL from a 10^-6 dilution tube into a plate, you counted 207 colonies. How many CFU are present in 1 mL?

2\.07x10^8

What does this graph represent?

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Bacterial Growth in a chemostat

Bacterial growth at high temperature

Bacterial growth in closed culture

Bacterial growth in continuous culture

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Bacterial growth in closed culture

A medium that has ingredients, such as yeast extract or casein milk proteins, which consist of a mixture of many chemical species in unknown proportions is commonly referred as

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Complex medium

Synthetic medium

Differential medium

Selective medium

Complex medium

A growth medium that favors the growth of some microorganisms but inhibits the growth of other microorganisms is a ______ medium.

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Neither selective nor differential

Selective

Selective and differential

Differential

Selective

You are measuring growth in a bacterial culture. The number of viable cells remained unchanged throughout the experiment but when you check the medium you found that the carbon source has been depleted (used up). In which phase of growth is the culture in?

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Lag phase

Early log phase

Late log phase

Stationary phase

Death phase

Stationary phase

Which of the following element combinations include only macronutrients required in large quantities by many microbes?

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C, O, S, Zi, Mn

S,O,Mg,Ca,K

H, N,K,Mg,Mo

P,H,S,Cu,Ni

S,O,Mg,Ca,K

Which of the following uses sunlight for energy and CO2 as a carbon source?

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Photogeterotrophs

Chemoautotrophs

Photoautotrophys

Chemoheterotrophs

Photoautotrophys

Neisseria meningitidis are cultured on chocolate agar, a medium containing red blood cells that help cultivate the fastidious bacteria to detectable levels. What type of growth medium is chocolate agar based on the description?

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differential

selective

enriched

selective and differential

enriched

The greater the concentration gradient, the faster the rate of diffusion

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T/F

True

You are working with a culture medium X that only allows the growth of halophiles (salt-loving microbes). Among. the halophiles, mannitol fermenters will produce acid that turns the pH indicator in the medium to yellow while mannitol non-fermenters will not change the color of the medium.

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Medium X is acting as a ______ medium.

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enrichment

selective

differential

selective and differential

selective and differential

If you start with 4 cells in an exponetial phase and divides to 10 cells every cell division, the total number of cells after “n: number of generations is proportional to_____.

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4x10^n

10x4^n

4xn^10

40

4x10^n

Calculate the colony forming units in 1 mL of the E. coli sample.

5\.7x10^7

Calculate the colony forming units in the whole 5 mL of the E. coli sample.

2\.85x10^9

One cell with generation time of 30 mins is inoculated into a culture medium. How many cells are there after 2 hours. (assuming all cells divide by binary fission in log phase and remained viable)

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96

180

16

32

16

Bacteria were transferred into a nutrient broth and placed in an incubator. The number of bacteria was determined at the end of each day: at start =10 bacteria, end of day= 20 bacteria, end of day 2= 40 bacteria, end of day 3= 80 bacteria, day 4= 160 bacteria.

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How many bacteria at end of Day 20?

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more than 10 million

1,280,000

6400

640

more than 10 million

At 4:00pm a closed flask of sterile broth is inoculated with 10,000 cells. At 8:00 pm the log phase culture has population of approx. 41 million cells. The estimated number or generations that has occurred is_______.

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Assume that the culture maintained log phase and every cell actively divided the whole time. Round.

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5

12

21

27

12

Shortest lag period would most likely be observed if a culture is transferred_______.

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to a medium at a different temp

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from a complex medium to a fresh complex medium

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to a medium at a different pH

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from a complex medium to a minimal medium

from a complex medium to a fresh complex medium

The figure below shows the growth curve of a bacteria in a batch (closed) culture. In which phase would you expect to find amount of carbon decreasing while. the. number of viable cells increasing?

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a

b

c

d

b

In cultures without oxygen, if streptococcus pyogenes decided to undergo fermentation, what happens to the electrons carried by NADH from glycolysis?

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will be donated back to glucose

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will be lost to the media

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will be donated to pyruvates



will be donated to electron transport system

will be donated to pyruvates

Fermentation produces more energy than anaerobic respiration.

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T/F

False

Oxygen is always required for the regeneration of NAD+ from NADH.

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T/F

False

Which is not an end product of fermentation?

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carbon dioxide

propionate

acetone

pyruvate

pyruvate

You feed E. coli 3 glucose molecules. How many ATP are created only through substrate level phosphorylation?

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6

10

8

12

12

The enzyme pyruvate kinase catalyzes the conversion of PEP to pyruvate. The phosphate group is transferred to ADP to form ATP. This is an example of:

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ATP synthesis through substrate level phosphorylation

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ATP synthase by oxidative phosphorylation

ATP synthesis through substrate level phosphorylation

Why do bacterial cells need fermentation?

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Synthesize more NADH

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Produce ATP by substrate level phosphorylation

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produce pyruvate for transition steps

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Recycle NADH back to NAD+

Recycle NADH back to NAD+

The Entner-Dourdoroff (ED) pathway and the pentose Phosphate Pathway (PPP) both produce NADH.

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T/F

False

Which of the following is NOT correct with respect to the redox pair NAD+/NADH?

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NADH can accept electrons from an electron transport system

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The reduced, nonaromatic ring of NADH is at a higher energy than the aromatic ring of NAD+

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the nicothinamide ring is a relatively stable aromatic structure

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the nicotinamide ring is heteoaromatic because it has a noncarbon atom in its 4th position.

NADH can accept electrons from an electron transport system

The enzyme pyruvate kinase catalyzes the conversion of PEP to Pyruvate. The phosphate group is transferred to ADP to form ATP. This reaction is an example of…

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ATP synthesis through substrate level phosphorylation

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ATP synthesis by oxidative phosphorylation

ATP synthesis through substrate level phosphorylation

The following is a condensed representation of the TCA cycle.

What is the name of the intermediate labelled 6?

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oxaloacetate

succinyl-CoA

Acetyl-CoA

Citrate

Citrate

E. coli could yield a max of 38 ATP per each glucose molecule by aerobic respiration. The same E. coli could also yield similar amount of ATP per each glucose molecule using fermentation as long as they have plenty of resources.

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T/F

False

Before pyruvate can enter the TCA cycle it must be transformed into what molecule?

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pyruvate dehydrogenase

oxaloacetate

Acetyl-CoA

Malate

Acetyl-CoA

The glyoxylate Bypass (shunt) can be utilized by some organisms when carbon sources are limited. The bypass incorporate a second molecule of Acetyl-CoA to form succinate and ______ molecules.

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isocitrite

oxaloacetate

malate

pyruvate

malate

Which of the following pathways would be fully operational only in respiring bacteria?

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fermentation

PPP

TCA

Glycolysis

TCA

How many electron carriers in total are created from just the TCA cycle from 2 glucose molecules?

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16

12

8

24

16

Production of ATP by ATP synthase directly depends on. which of the following?

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GTP

Proton motive force

electron carrier force

neutron motive force

Proton motive force

Which of the following is not a component of E. coli Electron Transport System?

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NADH Dehydrogenase (oxidoreductase)

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Terminal oxidase

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Cytochrome oxidase complex

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mobile electron carrier

Cytochrome oxidase complex

Anaerobic respiration uses an electron transport system while fermentation does not utilize an electron transport system.

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T/F

True

Oxygen is always required for oxidation of NADH to NAD+.

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T/F

False

Which of the. following statements about anaerobic respiration is true?

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it does not require ETS

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use oxidized ions of nitrogen, and sulfur as their final electron acceptor

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it generates only 2 ATP per single glucose

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uses oxygen as a final electron acceptor

use oxidized ions of nitrogen, and sulfur as their final electron acceptor

If you feed Streptococcus pyogenes 5 glucose molecules in aerobic condition, what is the maximum theoretical amount. of ATP. produced? (aerobic respiration)

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160

190

125

150

190

Which group of microorganisms are most likely to spoil a fish kept at a refrigerator (low temp)?

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psychrophiles

halophiles

anaerobes

thermophiles

psychrophiles

The following data show growth of 2 bacteria on different media.

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The table shows that S. aureus is an?

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alkalophile

anaerobe

mesophile

halophile

halophile

The term aerotolerant anaerobe refers to an organism that

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use oxygen if present in high concentration

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requires less oxygen than is present in air

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use oxygen but prefers nitrogen compounds

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does not use it oxygen and is not affected by it

does not use it oxygen and is not affected by it

Which of the following determines if microorganisms are going to use oxygen or not?

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their ability to use oxygen to oxidize glucose

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their ability to use oxygen during glycolysis

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their ability to use oxygen as a terminal electron acceptor

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their ability to have enzymes that deals with ROS

their ability to use oxygen as a terminal electron acceptor

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their ability to have enzymes that deals with ROS

Which shows phenol red test result of heterolactic fermentation?

left tube (yellow one)