MBS PRACTICE TEST 1

Which statement best describes a microbe according to the study guide? A. A nonliving particle that requires a microscope to be seen B. A living organism that requires a microscope to be seen C. Any organism that causes disease D. Any organism smaller than a human

B. A living organism that requires a microscope to be seen

Which organism is a prokaryote? A. Fungus B. Protozoan C. Bacterium D. Alga

C. Bacterium

Which characteristic distinguishes Archaea from Bacteria? A. Archaea have a nucleus B. Archaea have membrane-bound organelles C. Archaea do not have peptidoglycan D. Archaea have linear chromosomes

C. Archaea do not have peptidoglycan

Why are viruses different from living organisms? A. They are always smaller than bacteria B. They contain genetic material C. They cannot reproduce independently and lack their own metabolism D. They do not contain genetic material

C. They cannot reproduce independently and lack their own metabolism

Which observation supported the concept of biogenesis? A. Broth spontaneously produced microorganisms B. Pasteur's S-shaped flask prevented microorganisms from reaching the broth C. Microorganisms appeared in sealed flasks D. Boiling broth caused microorganisms to form

B. Pasteur's S-shaped flask prevented microorganisms from reaching the broth

Which scientist is associated with discovering that a mold could inhibit bacterial growth? A. Koch B. Pasteur C. Jenner D. Fleming

D. Fleming

Which best describes an opportunistic pathogen? A. A microorganism that always causes disease B. A microorganism that is less likely to cause disease in a healthy host but can cause disease under certain conditions C. A microorganism that cannot cause disease D. A microorganism that only infects plants

B. A microorganism that is less likely to cause disease in a healthy host but can cause disease under certain conditions

A researcher determines that 50 organisms are sufficient to infect 50% of an experimental population. What measurement is being described? A. LD50 B. ID50 C. Host range D. Incubation period

B. ID50

A pathogen has an ID50 of 10 organisms, while another has an ID50 of 10,000 organisms. What does the difference suggest? A. The second pathogen is more infectious B. Both pathogens have equal infectivity C. The first pathogen is more infectious based on the amount needed to infect 50% of the population D. The first pathogen is less infectious

C. The first pathogen is more infectious based on the amount needed to infect 50% of the population

Which is an example of a sign rather than a symptom? A. Headache B. Nausea C. Fatigue D. Fever measured at 102°F

D. Fever measured at 102°F

A person is infected with a pathogen but does not show symptoms and can transmit it to others. This person is best described as a: A. Carrier B. Reservoir C. Vector D. Fomite

A. Carrier

Which situation represents vertical transmission? A. Touching a contaminated doorknob B. Eating contaminated food C. A mother transmitting an infectious agent to her offspring D. Inhaling airborne droplets

C. A mother transmitting an infectious agent to her offspring

Which is an example of a fomite? A. Mosquito B. Contaminated doorknob C. Contaminated water D. Infected mother

B. Contaminated doorknob

An animal normally harbors a pathogen and can serve as a source for transmission to humans. This animal is a: A. Vector B. Reservoir C. Carrier D. Portal of entry

B. Reservoir

Which portal of entry is associated with breaks in the skin? A. Respiratory B. Gastrointestinal C. Parenteral D. Conjunctival

C. Parenteral

Which sequence correctly represents the basic stages of infectious disease? A. Illness → incubation → decline → prodromal → convalescence B. Incubation → prodromal → illness → decline → convalescence C. Prodromal → incubation → illness → convalescence → decline D. Incubation → illness → prodromal → decline → convalescence

B. Incubation → prodromal → illness → decline → convalescence

A student uses an acidic dye for a negative stain. What will primarily become stained? A. The cell wall B. The nucleus C. The background D. The capsule

C. The background

Which statement correctly compares brightfield and darkfield microscopy? A. Both have dark backgrounds B. Brightfield has a dark background, while darkfield has a bright background C. Brightfield has a lit background, while darkfield has a dark background D. Brightfield uses electrons, while darkfield uses visible light

C. Brightfield has a lit background, while darkfield has a dark background

Which combination correctly represents total magnification? A. Ocular + objective B. Ocular × objective C. Objective ÷ ocular D. Ocular − objective

B. Ocular × objective

Why is immersion oil used with the oil-immersion objective? A. To increase the wavelength of light B. To prevent light from refracting as it passes between the slide and lens C. To stain the specimen D. To increase the size of the specimen

B. To prevent light from refracting as it passes between the slide and lens

Which of the following is NOT one of the four interactions of light listed in your study guide? A. Reflection B. Refraction C. Scattering D. Magnification

D. Magnification

Light changes direction as it passes from one medium into another. Which interaction is occurring? A. Reflection B. Refraction C. Absorption D. Scattering

B. Refraction

Light strikes a surface and bounces back toward its original medium. This is: A. Reflection B. Refraction C. Absorption D. Scattering

A. Reflection

Which statement about electron microscopy is correct? A. It uses visible light and can routinely view living cells B. It has lower resolution than light microscopy C. It uses electrons and generally requires specimens that are not living D. It can only be used to view bacteria

C. It uses electrons and generally requires specimens that are not living

Which sequence correctly represents the major steps of a Gram stain? A. Mordant → primary stain → counterstain → decolorizer B. Primary stain → mordant → decolorizer → counterstain C. Counterstain → decolorizer → primary stain → mordant D. Primary stain → decolorizer → mordant → counterstain

B. Primary stain → mordant → decolorizer → counterstain

A student performs a Gram stain but accidentally skips the decolorizer. What is the most likely result? A. Gram-positive cells become pink B. Gram-negative cells may remain purple C. Both Gram-positive and Gram-negative cells become colorless D. Gram-positive cells become green

B. Gram-negative cells may remain purple

Which characteristic is most associated with Gram-positive bacteria? A. Thin peptidoglycan layer B. Thick peptidoglycan layer C. Outer membrane containing LPS D. No cell wall

B. Thick peptidoglycan layer

Why is an acid-fast stain particularly useful for Mycobacterium? A. It contains cellulose B. It contains mycolic acid in its envelope C. It lacks a cell wall D. It contains an outer membrane with LPS

B. It contains mycolic acid in its envelope

Which situation is an example of bioremediation? A. Using bacteria to break down environmental pollutants B. Using antibiotics to treat an infection C. Using a microscope to identify bacteria D. Using heat to sterilize equipment

A. Using bacteria to break down environmental pollutants

A bacterial growth curve shows four major phases. During which phase are cells adapting to their new environment rather than rapidly dividing? A. Lag phase B. Log phase C. Stationary phase D. Death phase

A. Lag phase