CH 7: Questions

Question 1

Which of the following can be used to isolate pure cultures of bacteria from mixtures: A. spread plates B. streak plates C. pour plates D. all of the above

Answer 1

all of the above

Question 2

T/F: serial dilutions can be used to estimate the total number of bacterial cells in a solution, including living and dead cells

Answer 2

false

Question 3

most bacterial and archaeal cells divide by

Answer 3

binary fission

Question 4

t/f: all bacterial and archaeal cells are diploid

Answer 4

false

Question 5

list the order of binary fission

Answer 5

cells elongates, replicates its chromosome, and separates the chromosome into the two parts of the cell , and a septum forms at midcells

Question 6

the __ is a group of proteins needed for DNA synthesis that assembles at the origin of the replication

Answer 6

replisome

Question 7

the process of forming a cross wall between wo daughter cells is known as

Answer 7

septation

Question 8

the cell wall of bacteria constrains the __ __ that results from the osmolarity of the cytoplasmic contents

Answer 8

turgor pressure

Question 9

the site at which replication of DNA starts in bacterial cells is known as the __ of ___

Answer 9

origin, replication

Question 10

T/F: the purpose of penicillin binding proteins is to link phospholipids together in the cellular membrane

Answer 10

false

Question 11

the actin- like protein that seems to be involved in determining cell shape is

Answer 11

MreB

Question 12

during cytokinesis, critical step in septation is the assembly of the

Answer 12

z ring

Question 13

the limitation on microbial growth rate at a high nutrient level is

Answer 13

the saturation of the transport proteins for nutrient uptake

Question 14

the total number of viable microorganisms remains constant in stationary phase because

Answer 14

either there is a balance between cell division and cell death or there is a cessation of cell division even though the cells may remain metabolically active

Question 15

cells may enter stationary phase because : A. the depletion of an essential nutrient b. a lack of available oxygen c. the accumulation of toxic waste products d. all of the choices

Answer 15

all of the choices

Question 16

a culture in a closed vessel to which no additional medium is added and from which no waste products are removed is called a __ culture

Answer 16

batch

Question 17

microorganisms are most nearly uniform in terms of chemical and physiological properties during what phase?

Answer 17

exponential

Question 18

T/F: when a young, vigorously growing culture of bacteria is transferred to fresh medium of the same composition, the lag phase is usually short or absent

Answer 18

true

Question 19

T/F: during the lag phase of microbial growth, the cells are metabolically inactive

Answer 19

false

Question 20

The length of the lag phase of growth can vary depending on:

Answer 20

condition of microorganisms, the nature of the growth medium, and the temperature

Question 21

T/F:when a young, vigorously growing culture of bacteria is transferred to fresh medium of DIFFERENT composition, the lag phase is usually short or absent

Answer 21

false; its longer

Question 22

T/F:the growth rate of a given species of microorganism is dependent on the composition of the medium in which it is grown

Answer 22

true

Question 23

microbial __ is an increase in cell constituents that may or may not be accompanied by an increase in cell number

Answer 23

growth

Question 24

a cultural system with constant environmental conditions maintained through continual provision of nutrient and removal of wastes is called ___ culture system

Answer 24

continous

Question 25

T/F: one of the major advantages of a continuous culture system is that the cells can be maintained in the exponential growth phase for extended periods of time

Answer 25

true

Question 26

in a continuous culture system, the rate at which media is added and removed is called the ___ rate

Answer 26

dilution

Question 27

organisms that are damaged by normal atmospheric levels of oxygen (20%) but require oxygen at levels of 2-10% for growth are called

Answer 27

microaerophiles

Question 28

when a microorganism is place in a(n) __ solution, water will enter the cell and cause it to burst unless something is done to prevent it

Answer 28

hypotonic

Question 29

the membranes of psychrophilic bacteria have relatively high levels of ___ fatty acids, which allow them to remain semi-fluid at cold temps

Answer 29

unsaturated

Question 30

organisms that are not drastically affected by increased pressure are called

Answer 30

barotoloerant

Question 31

organisms that require increased pressure for optimum growth are called

Answer 31

barophilic

Question 32

most microorganisms maintain their internal pH

Answer 32

near neutral (pH 7)

Question 33

organisms that grow near deep-sea volcanic vents are likely to be

Answer 33

thermophilic

Question 34

organisms that grow near deep - sea volcanic vents are likely to be

Answer 34

barophilic or barotolerant

Question 35

organism that grow in the mud under relatively nonturbulent bodies of water are likely to be

Answer 35

anaerobes

Question 36

T/F: obligate anaerobes are usually poisoned by molecular oxygen but may grow in aerobic habitats if associated with falcultative anerobes that use up all available oxygen

Answer 36

true

Question 37

DNA of thermophiles is stabilized by binding of special nucleoid-associated proteins

Answer 37

true

Question 38

membraines of some thermophilic archaea are stablized by ether linked phospholipids

Answer 38

true

Question 39

organisms that can grow in habitats with low water activity by maintaining a high internal salt concentration are called __ organism

Answer 39

osmotolerant

Question 40

organisms that require high levels of sodium chloride in order to grow are called __ organisms

Answer 40

halophilic

Question 41

organisms that have their optimum growth pH btwn 0.0 and 5.5 are called

Answer 41

acidophiles

Question 42

membranes of thermophilic bacteria are stabilized by phospholipids with fatty acids that :

Answer 42

tend to be more saturated

Question 43

organism that have their optimum growth pH between 5.5 and 8.0 are called

Answer 43

neurophiles

Question 44

organisms that have their optimum growth pH between 8.5 and 11.5 are called

Answer 44

alkaliphiles

Question 45

organisms that growth best at pH levels above 10 are called

Answer 45

extreme alkaliphiles

Question 46

many microbes that live in environments where there is high exposure to light use __ to provide protection from photoxidation by singlet oxygen

Answer 46

carotenoids

Question 47

complex microbial communities that grow tightly adhered to surfaces are called

Answer 47

biofilms

Question 48

quorum sensing in gram-positive bacteria generally involves the use of __ as the external signaling molecules

Answer 48

oligopeptides

Question 49

T/F: a microbial environment containing high nutrient concentration is called an oligotrophic environment

Answer 49

false

Question 50

a phenomenon in which bacteria monitor their own population density

Answer 50

quorum sensing

Question 51

quorum sensing depends on the sensing of signal __ molecules

Answer 51

protein

Question 52

quorum sensing plays an important role in formation of biofilms by what organism?

Answer 52

Pseudomonas aeruginosa

Question 53

organisms that ignore oxygen and grow equally well in its presence or absence are called

Answer 53

aerotolerant