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Microbiology > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

Which of the following terms are mismatched?

A

gram-negative outer membrane; teichoic acids

Correctly matched:
LPS; outer membrane
Peptidoglycan; D-alanine
Endospore; dipicolinic acid

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2
Q

Which of the following terms refers to a bacterium with a spherical shape?

A

Coccus

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3
Q

Which of the following statements best describes how fimbriae and capsules differ from each other?

A

Fimbriae are filamentous structures; whereas capsules are not

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4
Q

What molecules reduce the water content of a bacterial endospore?

A

Dipicolinic acid and calcium

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5
Q

What molecule cleaves the b-1,4 bond between N-acetylglucosamine and N-acetylmuramic acid?

A

lysozyme

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6
Q

The cytoplasmic membrane is termed “semi-permeable” because some substances, like water and alcohols, can pass freely through while others, life sugars, amino acids, and ions, cannot. What molecular characteristics largely determine whether or not a substance can pass through the membrane?

A

size and hydrophobicity

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7
Q

Which of the following is NOT a part of the endospore structure?

A

Water

Spore coat, cortex, and exosporium are a part of the structure.

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8
Q

Which of the following is the best explanation for how membranes conserve energy?

A

They allow the development of a proton motive force, which drives the activity of ATP synthase.

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9
Q

Which of the following is NOT a function of the cytoplasmic membrane?

A

protection from hypotonic stress caused by osmosis

It does provide the framework for the generation of proton motive force, also provides a barrier to hydrophilic molecules, and transports nutrients.

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10
Q

Explain why the presence of a capsule or slime layer would benefit a bacterial cell

A

These outer layers can aid in attachment to solid surfaces

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11
Q

Which of the following characteristics was found in the earliest cellular organisms?

A

anaerobic metabolism

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12
Q

A pure culture

A

is a population of identical cells

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13
Q

Microbes that live at high temperatures in hot springs are

A

called extremophiles

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14
Q

Which types of organisms are the most important for the maintenance of life on Earth?

A

Microorganisms

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15
Q

Microbes playing a role in nitrogen fixation in plants live in _____, while those playing a role in the digestive tract of certain herbivores live in ______

A

nodules/rumens

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16
Q

Microbial ecology is the study of

A

microorganisms in their natural environments

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17
Q

What kind of cells do NOT have a cell wall?

A

animal cells

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18
Q

A colony on a Petri plate arises from a single cell. How many cells does a typical bacterial colony contian?

A

10^7

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19
Q

A microbial cell’s membrane is considered _______, because its internal constituents are maintained within the cell. However, it also imports and exports other molecules in response to its environment.

A

semipermeable

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20
Q

In what/which domain(s) of life is/are microorganisms represented

A

Archaea, Bacteria, Eukarya

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21
Q

An example of a differential stain is ____

A

The gram stain

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22
Q

Actin is found within

A

eukaryotic microfilaments

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23
Q

Which of the following statements is TRUE

A

Eukaryotic flagella do not rotate in the same manner as prokaryotic flagella

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24
Q

All eukaryotes contain

A

a membrane-enclosed nucelus

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25
Q

What would happen to a eukaryotic cell if the membranes of its lysosomes are disrupted?

A

The cell would be digested from the inside out

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26
Q

While examining cellular material, you find that organelle DNA is present. What organelle(s) must be within the sample?

A

chloroplasts or mitochondira

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27
Q

The Golgi complex functions to

A

both modify and sort proteins into those destined for secretion and those that function in membrane structures

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28
Q

Which list contains the correct components of a bacterial flagellum?

A

filament, hook, basal body

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29
Q

Where within a eukaryotic cell is ribosomal RNA (rRNA) synthesized?

A

nucleolus

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30
Q

All of the following contain chloroplasts in their cells except ______

A

cyanobacteria

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31
Q

Modern endosymbiotic theory proposed that eukaryotic cells arose from

A

a bacterial cell taking up residence within an archaeal cell

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32
Q

Under a microscope, you see a bacterium quickly reverse direction and continue to move and, therefore, conclude that

A

The bacterium has polar flagella

33
Q

Which of the following characteristics was found in the earliest cellular organisms?

A

anaerobic metabolism

34
Q

ATP is an important compound in all living cells. This is because _____

A

it is an energyrich compound that can be broken down to liberate energy for cellular function

35
Q

Lactic acid bacteria convert pyruvate to lactic acid via lactate dehydrogenase. Which of the following statements is FALSE

A

The enzymatic reaction requires aerobic conditions

TRUE: LActic acid is formed by the reduction of pyruvate, NADH produced during glycolysis is oxidized to NAD+, and fermentation allows for the continued production of ATP

36
Q

The reduction potential (E0’) of a substrate reflects its tendency to donate or accept electrons. The larger the difference (deltaE0’) between the reduction potential of the electron donor and the electron acceptor, ____

A

the greater the change in free energy (deltaG0’), and the greater the energy released

37
Q

What is the correct classification for a microorganisms that can oxidize Fe2+ to produce energy?

A

chemolithotroph

38
Q

The ability of a substance to become oxidized or reduced is known as the

A

reduction potential

39
Q

Heterotrophic microorganisms acquire their cell carbon

A

from organic chemicals

40
Q

Making wine and bread uses the metabolic activities of yeast cells, known as

A

Fermentation

41
Q

Redox reactions in microbial cells require small molecules to serve as electron carriers. An example of an electron carrier is

A

NAD+

42
Q

Enzymes are cellular catalysts. This is because

A

They lower the activation energy of a reaction, thereby increasing its rate

43
Q

Which of the following are most likely to be autotrophic?

A

chemolithotrophs and phototrophs

44
Q

During glycolysis, the change in free energy is greatest in which of the following molecules?

A

phosphoenolpyruvate

45
Q

Which of the following molecules involved in electron transport has the most positive reduction potential?

A

Cytochromes

46
Q

The sum of all biosynthetic reactions in a cell is known as

A

anabolism

47
Q

Why are electron carriers necessary in respiration?

A

to facilitate the transfer of electrons from primary donor to terminal acceptor, and to set up a proton motive force

48
Q

In addition to completing the oxidation of glucose during respiration, the citric acid cycle is important for which of the following processes?

A

the synthesis of amino acids using a-ketoglutarate and succinate as precursors

49
Q

Electron carriers used in electron transport chains are always found in membranes. Which of the following statements is NOT a reason why electron transport chains are found in membranes?

A

So that they can transport NADH out of the cells to the periplasm

TRUE:
So that they can efficiently pass electrons in sequence from the carriers with the more negative reduction potentials to those with the more positive reduction potentials, so that electron-only carriers can be arranged to alternate with electron-plus proton carriers in the chain, and so that the electron carriers can be oriented within the membrane such that protons are passed from one side of the membrane to the other.

50
Q

Distinguish how fermentation and respiration differ

A

Fermentation forms organic acids and takes place in the absence of oxygen, while respiration forms water and carbon dioxide in the presence of oxygen

51
Q

How many ATP are generated during respiration?

A

38

52
Q

Proton motive force generates an energized membrane where

A

H+ accumulates on the outside of the membrane and OH- accumulates on the inside of the membrane

53
Q

Which of the following statements is FALSE

A

Most available nitrogen is in organic forms

TRUE: most bacteria are capable of using ammonia as their sole nitrogen source, some bacteria are able to use nitrates or nitrogen gas as their nitrogen source, and nitrogen is a major component of proteins and nucleic acids.

54
Q

Which of the following statements is NOT true about fermentation?

A

Fermentation products are limited to lactic acid and carbon dioxide.

TRUE: fermentation yields less ATP than respiration, fermenting organisms are a diverse group, and fermenting organisms rely on substrate-level phosphorylation to conserve energy.

55
Q

Which of the following antimicrobial agents kills bacteria?

A

bactericidal agents

56
Q

A closed system, used for bacterial growth, where nothing is added and nothing is removed is called a

A

a batch culture

57
Q

Which choice best illustrates what occurs in the stationary phase of bacterial growth?

A

cryptic growth, where the number of new cells equals the number of dying cells

58
Q

Which of the following choices represents one of the most common reasons bacterial growth is limited in a batch culture?

A

The accumulation of waste products is toxic to cells

59
Q

In a batch culture, bacterial cultures typically exhibit four different phases of growth. In which phase are the cells rapidly synthesizing proteins, but cell numbers are not changing?

A

lag phase

60
Q

Under which of the following conditions is a long lag phase LEAST likely to occur?

A

An exponentially growing culture is transferred into the same medium under the exact same conditions of growth

61
Q

What is the partition called that forms between two dividing daughter cells?

A

Septum

62
Q

Which is one of the major elements that is required by cells, making up most of their dry weight?

A

Sulfur (S)

63
Q

For unicellular organisms within certain limits, what is the relationship between optical density and cell numbers?

A

proportional

64
Q

Which of the following is NOT a difficulty when using turbidity to track cell growth?

A

Some bacteria have short generation times

65
Q

What type of growth explains the plaque buildup on your teeth every morning even though you brushed your teeth right before bed?

A

exponential growth

66
Q

The citric acid cycle

A

completely oxidizes pyruvate to CO2

67
Q

Staining increases the visible contrast of cells compared with the background. Because the Gram stain results in some types of bacteria staining purple and other types appearing pink, this is called ______ staining.

A

Differential

68
Q

Which statement below demonstrates why the majority of organisms are heterotrophs?

A

The majority of organisms obtain their carbon form organic sources.

69
Q

What components of the peptidoglycan can be altered to change the thickness of a gram-negative peptidoglycan layer?

A

The number of NAG/NAM sheets

70
Q

Which of the following would be the order in which a facultative organism would break down glucose?

A

It would first respire glucose in the presence of oxygen and ferment glucose if oxygen is lacking

71
Q

The number of colonies obtained in a plate count does NOT depend on the size of the colony but it does depend on

A

the type of culture medium, the inoculum volume, and the incubation time

72
Q

The reduction potential of a substance reflects its tendency to donate or accept electrons. The larger the difference between the reduction potentials of the electron donor and the electron acceptor

A

the greater the change in free energy and the greater the energy released

73
Q

The role of an enzyme includes all EXCEPT which of the following?

A

reducing the rate of a reaction to allow for better control

74
Q

Given that the cytoplasmic membrane has a fluid dynamic nature, with phospholipids and proteins able to move about within the bilayer structure, what force or structure keeps the membrane from falling apart?

A

hydrophilic/hydrophobic forces

75
Q

Microbial contamination is prevented by the

A

use of aseptic technique

76
Q

Four bacteria have been isolated from the soil, and each one uses a different final electron acceptor that is not oxygen. Which will produce the most ATP per FADH2 molecule (E0 for FADH = -0.42V)

A

One that uses nitrite (E0= +0.44V)

77
Q

In a bacterial cell undergoing binary fission and balanced growth

A

the proportion of all cell consituents will remain the same over time

78
Q

Optical density and viable cell concentration are LEAST proportional to each other during the

A

death phase

Microbiology (3 decks)

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