Practice Exam 1

Any molecule that serves as an electron receptor will be

reduced

Which type of chemical reaction in cells release energy?

catabolic

Which type of metabolic reaction synthesizes large molecules from smaller ones?

anabolic

What term is used to describe the gain of one or more electrons by a molecule?

reduction

Why are denatured enzymes no longer functional?

denatured enzymes lose the secondary and tertiary structures that determine the correct shape of the active site

How does a competitive inhibitor slow enzyme catalysis?

they compete with the substrate for the enzyme's active site

What enables competitive inhibitors to bind to a specific enzyme?

competitive inhibitors have structures that resemble the enzymes substrate

If high amounts of sulfanilamide are in the presence of an enzyme whose substrate is PABA, what outcome is expected?

PABA will not be catalyzed

Which of the following statements regarding competitive inhibitors is true?

competitive inhibitors decrease the rate of enzyme activity

How does a noncompetitive inhibitor reduce an enzyme's activity?

the inhibitor binds to the enzyme in a location other than the active site changing the shape of the active site

What would be the likely outcome if you increased the concentration of substrate for an enzyme in the presence of a noncompetitive inhibitor?

no change in enzyme activity would be observed

How is nevirapine used to treat HIV infections?

It alters the active site of reverse transcriptase, decreasing that enzyme's activity.

which of the following is NOT a basic process of life?

sexual reproduction

A bacterial cell stains positive with the acid-fast stain. Which of the following is FALSE?

it has a cell wall that contains endotoxin

One distinction between Gram-positive and Gram-negative cells is the relative thickness of peptidoglycan. Which group has a thicker layer of peptidoglycan?

gram-positive

Which end of a phospholipid orients itself toward the interior of a phospholipid bilayer?

the hydrocarbon tail

What term describes an aqueous solution in which animal cells swell and burst?

hypotonic

why do some bacteria form endospores?

A defense strategy against hostile conditions

what never has cell walls?

animal cells

which of the following statements about the endoplasmic reticulum (ER) is correct?

transport system within the cytoplasm

Consider bacteria, fungi, protozoa, and viruses. Which of these is generally smallest in size?

viruses

what is the main difference in gram-positive and gram-negative bacteria?

gram-positive bacteria have a cell wall with a thick layer of peptidoglycan, while gram-negative bacteria have a thin layer of peptidoglycan and a extra outer membrane

Among endospores, fimbriae, flagella, and inclusions, which allow bacteria to survive very harsh conditions?

endospores

one-thousandth of a meter is.... (67)

millimeter

which style of microscope uses a white light source below the specimen to illuminate the specimen?

bright-field microscope

after gram staining E.coli are pink in color. This means..

it's gram negative

if safranin is left out of a Gram staining process, what happens?

gram-positive cells would be purple and gram-negative cells would be colorless/transparent

A chemoheterotroph obtains its energy from ____ and its carbon from _____

redox reactions ; organic

A blank organism requires oxygen for growth

obligate aerobic

what type of media is used to prevent growth of certain microbes while allowing growth of others?

selective media

CFU (colony-forming units) are the source for

pure cultures

Blood agar plates are an example of ____ medium

differential

Microbes in the __________ phase of the microbial growth curve are most susceptible to antimicrobial drugs.

log phase

blank are used for communication by microbes in biofilms

quorum-sensing molecules

What type of microorganisms reproduce by binary fission?

unicellular microorganisms

what term describes a procedure that destroys all microbes?

sterilization

Which of the following is an example of pasteurization?

a heat is used to kill potential pathogens in apple juice

which of the following is most susceptible to antimicrobial agents?

vegetative bacteria

Desiccation, a time-honored method of preserving food, is effective because the

water content is too low to support metabolic function

Compared to moist heat methods, dry heat needs which of the following in order to sterilize effectively?

higher temperature and increased time

Technically speaking, which antimicrobial drugs are produced naturally?

antibiotics

any drug that acts against a disease is called a (n) (analog/antibiotic/chemotherapeutic agent)

chemotherapeutic

which of the following is NOT a direct mode of action of antimicrobial drugs?

inhibition of flagella information

Bacitracin blocks the transport of NAG and NAM across the cytoplasmic membrane to the cell wall. Like other antimicrobials that block cell wall synthesis, this would result in weak cell walls and

cell lysis due to the effect of osmotic pressure

Amoxicillin is very effective for treating infections with Gram-positive bacteria but rarely causes side effects in humans. This is an example of

selective toxicity

Many antimicrobials have side effects. Which side effect can be circumvented, at least in part, by the use of probiotics?

disruption of normal microbiota

The therapeutic window of an antimicrobial is the

range of concentrations at which the antimicrobial is both effective and non-toxic.

Competition between beneficial microbes and potential pathogens is called microbial (antagonism/synergy/toxicity)

antagonism

If a particular bacterial species is resistant to beta-lactam antibiotics, which of the following might you expect to find inside the bacterial cells?

R plasmids

It is inappropriate to prescribe antibacterial agents to treat colds or flu because

hese diseases are caused by viruses.