Chapter 7 Microbiology

Both human and bacterial cells divide by mitosis. True or False

False

Cell division is triggered exclusively when cells attain a threshold mass. True or False

False

Cells cannot begin a new round of replication until they have completely finished dividing. True or False

False

DNA helicase is responsible for adding nucleotides to the growing end of the DNA. True or False

False

Environmental factors control microbial growth through their influence on enzyme activity. True or False

False

Escherichia and Salmonella are cocci that divide by binary fission. True or False

False

Place the steps of binary fission in the correct order to test your understanding of bacterial cell division.

1) Cell enlarges and the chromosome is replicated. 2)Septum is completed. 3)A transverse septum grows inward as the two chromosomes are pulled towards opposite ends of the elongating cell. 4)Daughter cells are separated or may remain attached.

Rod-shaped bacteria synthesize new cell walls over the entire surface of the cell. True or False

True

The degree of turbidity in a broth culture correlates to the amount of cell growth. True or False

True

Choose the phase of the bacterial growth curve during which a bacterial population has the shortest doubling time. a) Exponential growth phase b) Lag phase c) Death phase d) Stationary growth phase

a) Exponential growth phase

Select the physical factors below that can affect microbial growth. a) Temperature b) Radiation (visible light, UV, gamma) c) Availability of nutrients d) Barometric pressure e) Extreme drying/dehydration g) pH level

a) Temperature b) Radiation (visible light, UV, gamma) c) Availability of nutrients g) pH level

By keeping food cold, the growth of microorganisms is ______. a) minimized b) increased c) not changed d) stopped and they are killed

a) minimized

In this animation, on which day does the room temperature orange begin to show spoilage? a) Day 12 b) Day 8 c) Day 4 d) Day 0

b) Day 8

Select the characteristics of biofilms that differentiate them from planktonic bacteria. Check all that apply. a) Microorganisms live singly and independently. b) Microorganisms participate in quorum sensing. c) Microorganisms secrete extracellular material, usually polysaccharide, that forms a matrix. d) Microorganisms are readily eradicated using antibiotics. e) Microorganisms exist as part of a diverse interdependent community.

b) Microorganisms participate in quorum sensing. c) Microorganisms secrete extracellular material, usually polysaccharide, that forms a matrix. d) Microorganisms are readily eradicated using antibiotics. e) Microorganisms exist as part of a diverse interdependent community.

Which enzyme is NOT involved in DNA replication? a) Gyrase b) RNA polymerase c) Helicase d) DNA polymerase

b) RNA polymerase

Select the statement that most accurately reflects biofilms. a) They communicate via remote sensing. b) They are associated with chronic ear infections. c) They are easily treated with antibiotic therapy. d) They are comprised of one microbial species.

b) They are associated with chronic ear infections.

Select the statements that characterize obligate saprobes. Check all that apply. a) They live in a host. b) They live on a host. c) They feed off of dead organic matter in water. d) They feed off of dead organic matter in soil. e) They lack enzymes to degrade organic matter.

b) They live on a host. d) They feed off of dead organic matter in soil. e) They lack enzymes to degrade organic matter.

In the viable plate count method, a measured volume of a culture is evenly spread across an agar surface and incubated. Each _____ represents one _____ from the original sample. a) generation; cell b) colony; cell c) species; colony d) cell; colony

b) colony; cell

Microorganisms that live in severe habitats, such as very hot, acidic, or salty environments, are called ______. a) halophiles b) extremophiles c) barophiles d) psychrophiles e) thermophiles

b) extremophiles

The generation time of Mycobacterium tuberculosis is ______. a) 10 days b) 33 hours c) 12 hours d) 3 hours e) 30 minutes

c) 12 hours

How many generations does it take for a single bacterial cell to become 256? a) 6 b) 5 c) 8 d) 7 e) 9

c) 8

How common are food spoilage microorganisms? a) Almost none of our foods contain them. b) A few of our foods contain them. c) Almost all of our foods contain them. d) They are extremely rare.

c) Almost all of our foods contain them.

Most cultured bacteria tend to multiply by ______. a) fragmentation b) budding c) binary fission d) sexual reproduction

c) binary fission Cell division is triggered exclusively when cells attain a threshold mass.

The structure that divides the bacterial cell in two is termed the ______. a) cell plate b) demarcation zone c) cross septum d) fission line e) cleavage furrow

c) cross septum

This animation shows that food spoilage microorganisms can be classified by their a) growth time preferences. b) food source. c) growth temperature preferences. d) growth moisture preferences.

c) growth temperature preferences.

Cells must ______ their DNA prior to cell division a) transcribe b) translate c) replicate d) hydrolyze

c) replicate

The FtsZ protein is needed to form the _____. a) ribosomes b) replicated DNA c) septum d) All of these are correct.

c) septum

The energy source for contraction of the FtsZ ring during cell division comes from _____. a) the hydrolysis of gyrase b) the synthesis of G c) the hydrolysis of GTP d) the hydrolysis of ATP

c) the hydrolysis of GTP

An organism with a temperature growth range of 45°C to 60°C would be called a(n) ______. a) facultative psychrophile b) thermoduric microbe c) thermophile d) extremophile e) psychrophile

c) thermophile

Carbon, nitrogen, oxygen and hydrogen are considered _______ because they are required in relatively large quantities, whereas manganese, zinc, and copper are considered _____ because they are required in very small quantities. a) elements, atoms b) nonessential, essential c) micromolecules, macromolecules d) macronutrients, micronutrients

d) macronutrients, micronutrients

The most common organisms causing food spoilage are bacteria, _______. a) insects and parasites b) molds and insects c) yeasts and insects d) yeasts and molds

d) yeasts and molds

Microorganisms require large quantities of ______ for use in cell structure and metabolism. a) water b) trace elements c) growth factors d) electrolytes e) macronutrients

e) macronutrients

Microorganisms require small quantities of ______ for enzyme function and maintenance of protein structure. a) macronutrients b) electrolytes c) growth factors d) water e) trace elements

e) trace elements