C1 Sample Questions from Brock

Question 1

Which of the following statements is FALSE?
A) Microbial cells can exist as single cells.
B) Microbial cells carry out their life processes of growth independently.
C) Microbial cells include both bacteria and viruses.
D) Microbial cells are surrounded by a plasma membrane.

Answer 1

C) Microbial cells include both bacteria and viruses.

Viruses are not cells; they are acellular entities that require a host cell for replication. Bacteria are cellular microorganisms.

Question 2

Which of the following statements is correct?
A) Microorganisms are significant contributors to the total biomass on Earth.
B) Microorganisms represent a much smaller amount of Earth’s biomass than plants.
C) Microorganisms represent a much smaller amount of Earth’s biomass than animals.
D) Microorganisms are significant in number, but not in overall biomass.

Answer 2

A) Microorganisms are significant contributors to the total biomass on Earth.

While individually tiny, the sheer number of microorganisms across diverse habitats makes them a major component of Earth’s biomass.

Question 3

In what/which domain(s) of life is/are microorganisms represented?
A) Archaea
B) Bacteria
C) Eukarya
D) All of the above

Answer 3

D) All of the above. Microorganisms are found in all three domains of life.

Question 4

Differential selection and reproduction of phenotypes occurs during a process called
A) cellular differentiation.
B) evolution.
C) growth.
D) transformation.

Answer 4

B) evolution.

Differential selection and reproduction of phenotypes are the core principles of evolution by natural selection.

Question 5

Biological catalysts involved in the acceleration of the rate of chemical reactions are called
A) catalytic converters.
B) growth agents.
C) evolutionary molecules.
D) enzymes.

Answer 5

D) enzymes.

Enzymes are biological catalysts that speed up chemical reactions.

Question 6

Regarding early life on Earth
A) microbial life existed for billions of years before plant and animal life.
B) microbial life existed long before animals but has been around for about the same amount of time as plants.
C) microbial life, plant life, and animal life all appeared at about the same time.
D) it is impossible to determine which type of life first appeared.

Answer 6

A) microbial life existed for billions of years before plant and animal life.

Evidence suggests microbial life arose early in Earth’s history, long before more complex multicellular life.

Question 7

The person who described the “wee animalcules” was
A) Robert Hooke.
B) Antoni van Leeuwenhoek.
C) Louis Pasteur.
D) Ferdinand Cohn.

Answer 7

B) Antoni van Leeuwenhoek.

Leeuwenhoek is credited with the first observations of microorganisms, which he called “wee animalcules.”

Question 8

Walther Hesse and ________ pioneered the use of agar as a solidifying agent.
A) Louis Pasteur
B) Ferdinand Cohn
C) Robert Koch
D) Sergei Winogradsky

Answer 8

C) Robert Koch

While Hesse initially suggested agar, Koch and his lab popularized its use in microbiology.

Question 9

Which of the following is/are characteristic of all cellular organisms?
A) communication
B) evolution
C) motility
D) communication, evolution, and motility

Answer 9

B) evolution.

All cellular organisms are subject to evolutionary processes. Motility and communication are not universal traits.

Question 10

Deduce why viruses are excluded from the ribosomal RNA—based tree of life.
A) Some viruses contain multiple strands of RNA.
B) Their genetic elements cannot be sequenced.
C) They can infect other organisms, which complicates the genetic comparisons.
D) They lack ribosomal RNA (rRNA).

Answer 10

D) They lack ribosomal RNA (rRNA).

Ribosomal RNA is used to construct the tree of life. Since viruses don’t have ribosomes, they cannot be included in this tree.

Question 11

Louis Pasteur developed the vaccine(s) for
A) anthrax only.
B) fowl cholera only.
C) rabies only.
D) anthrax, fowl cholera, and rabies.

Answer 11

D) anthrax, fowl cholera, and rabies.

Pasteur developed vaccines for all three diseases.

Question 12

The discovery of antibiotics and other important chemicals led to the field of
A) industrial microbiology.
B) agricultural microbiology.
C) marine microbiology.
D) aquatic microbiology.

Answer 12

A) industrial microbiology.

The discovery of these chemicals led to their exploitation for industrial processes, giving rise to industrial microbiology.

Question 13

Microbial sterilization is used to
A) decrease the possibility of contaminants growing in a culture.
B) kill bacteria but not necessarily viruses or other microbes.
C) kill all microbes in or on objects.
D) clean a work area.

Answer 13

C) kill all microbes in or on objects.

Sterilization aims for complete elimination of microbial life.

Question 14

Transparent double-sided dishes used for growing microbes are most commonly called
A) Petri dishes.
B) baker dishes.
C) sterilization plates.
D) culture medium plates.

Answer 14

A) Petri dishes.

These dishes provide a convenient and sterile surface for microbial growth.

Question 15

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) rumens / nodules
B) nodules / rumens
C) nodules / fortrans
D) fortrans / rumens

Answer 15

B) nodules / rumens

Nitrogen-fixing bacteria reside in root nodules of plants, while those aiding digestion in herbivores are found in the rumen.

Question 16

Which of the following is NOT an accomplishment of Louis Pasteur?
A) determined that the alcohol-making process was mediated by microbial fermentation and thus refuted the theory of spontaneous generation
B) developed enrichment culture techniques
C) developed heat sterilization techniques that involved the creation of a specialized swan-necked flask
D) developed the first rabies vaccine and treated thousands of individuals

Answer 16

B) developed enrichment culture techniques

Beijerinck developed enrichment culture techniques.

Question 17

The theory of spontaneous generation was refuted by the work of
A) Louis Pasteur.
B) Robert Koch.
C) Robert Hooke.
D) Antoni van Leeuwenhoek.

Answer 17

A) Louis Pasteur.

Pasteur’s swan-necked flask experiments disproved spontaneous generation.

Question 18

A Pasteur flask has a(n)
A) swan neck to prevent particulate matter from getting into the main body of the flask.
B) double neck so two substances may be added at the same time.
C) secondary opening at the base to allow for drainage.
D) inverted upper edge to prevent spillage while swirling.

Answer 18

A) swan neck to prevent particulate matter from getting into the main body of the flask.

This design allowed air exchange but prevented dust and microbes from entering the sterile broth.

Question 19

Predict how Pasteur’s conclusions on spontaneous generation with swan flasks would have changed if he worked with and maintained the flasks in a sterile laminar flow hood.
A) Sterilization of the swan flask solutions would not have been necessary to reject spontaneous generation. If he did sterilize the flasks, the spontaneous generation hypothesis would have been supported.
B) His incubation times would not have been sufficient to refute spontaneous generation.
C) Pasteur’s flasks never would have putrefied, and the experiment would not have refuted spontaneous generation.
D) Viruses would have still been present, and his conclusion would have been unchanged.

Answer 19

C) Pasteur’s flasks never would have putrefied, and the experiment would not have refuted spontaneous generation.

In a sterile environment, there would be no contaminating microbes to grow, even if the flask neck was broken, thus not supporting his original conclusion.

Question 20

A pure culture
A) is sterile.
B) is a population of identical cells.
C) is made of a clearly defined chemical medium.
D) contains one microbial cell.

Answer 20

B) is a population of identical cells.

A pure culture originates from a single cell and, therefore, consists of genetically identical offspring.

Question 21

Martinus Beijerinck was the first to isolate
A) green algae.
B) certain nitrogen-fixing root nodule bacteria.
C) certain sulfate-reducing bacteria.
D) green algae, certain nitrogen-fixing root nodule bacteria, and certain sulfate-reducing bacteria.

Answer 21

D) green algae, certain nitrogen-fixing root nodule bacteria, and certain sulfate-reducing bacteria.

Beijerinck made significant contributions to isolating these diverse microbial groups.

Question 22

Chemolithotrophy involves
A) oxidation of organic compounds.
B) oxidation of inorganic compounds.
C) reduction of organic compounds.
D) metabolic autotrophy.

Answer 22

B) oxidation of inorganic compounds.

Chemolithotrophs obtain energy from the oxidation of inorganic substances.

Question 23

Developments in the fields of immunology and medical microbiology were practical extensions of the work of
A) Sergei Winogradsky.
B) Antoni van Leeuwenhoek.
C) Joseph Lister.
D) Robert Koch.

Answer 23

D) Robert Koch.

Koch’s postulates and work on infectious diseases laid the groundwork for these fields.

Question 24

Robert Koch contributed to the field of microbiology by being the first person to
A) develop the tuberculin test only.
B) formulate four postulates for definitively linking a specific microorganism to a specific disease only.
C) use agar as a solidifying agent in growth media only.
D) develop the tuberculin test, formulate four postulates for definitively linking a specific microorganism to a specific disease, and use agar as a solidifying agent in growth media.

Answer 24

D) develop the tuberculin test, formulate four postulates for definitively linking a specific microorganism to a specific disease, and use agar as a solidifying agent in growth media.

Koch achieved all three of these milestones.

Question 25

Mycobacterium tuberculosis is very difficult to stain because of the
A) presence of ribosomes in the cytoplasm.
B) location of the DNA within the cell.
C) large amounts of a waxlike lipids present in its cell wall.
D) lack of a cell wall.

Answer 25

C) large amounts of a waxlike lipids present in its cell wall.

This waxy layer makes traditional staining difficult, requiring specialized techniques like acid-fast staining.

Question 26

Louis Pasteur’s most famous success was his work on
A) Mycobacterium tuberculosis.
B) the rabies vaccine.
C) optical isomers.
D) cultivation of coli.

Answer 26

B) the rabies vaccine.

While Pasteur made many contributions, the rabies vaccine is particularly noteworthy.

Question 27

Microorganisms play key roles in the cycling of important nutrients in plant nutrition, particularly those of
A) carbon only.
B) nitrogen only.
C) sulfur only.
D) carbon, nitrogen, and sulfur.

Answer 27

D) carbon, nitrogen, and sulfur.

Microbes play critical roles in the biogeochemical cycles of these elements.

Question 28

Microbial ecology is the study of
A) microbial processes in the rhizosphere that benefit plant growth.
B) the diversity and activities of microorganisms.
C) the grouping and classifying of microorganisms.
D) microorganisms in their natural environments.

Answer 28

D) microorganisms in their natural environments.

Microbial ecology studies the relationships between microorganisms and their surroundings.

Question 29

Robert Koch received the 1905 Nobel Prize in Physiology or Medicine for
A) developing a smallpox vaccination.
B) identifying Mycobacterium tuberculosis as the causative agent of tuberculosis.
C) making an effective rabies vaccine.
D) developing a smallpox vaccination, identifying Mycobacterium tuberculosis as the causative agent of tuberculosis, and making an effective rabies vaccine.

Answer 29

B) identifying Mycobacterium tuberculosis as the causative agent of tuberculosis.

This was a landmark achievement in medical microbiology.

Question 30

Archaea and Bacteria are unified as prokaryotes in lacking _______ which Eukarya contain, such as mitochondria.
A) membranes
B) nuclei
C) membrane-enclosed organelles
D) nuclei and membrane-enclosed organelles

Answer 30

D) nuclei and membrane-enclosed organelles

Prokaryotes lack both a nucleus and membrane-bound organelles, while eukaryotes possess them.

Question 31

______ was the first to identify a new form of autotrophy in which energy is obtained from oxidizing inorganic compounds called ______.
A) Martinus Beijerinck / heteroautotrophy
B) Martinus Beijerinck / chemolithotrophy
C) Sergei Winogradsky / heteroautotrophy
D) Sergei Winogradsky / chemolithotrophy

Answer 31

D) Sergei Winogradsky / chemolithotrophy

Winogradsky discovered this metabolic process.

Question 32

Electron microscopy has greater ________ than light microscopy, because the wavelength of visible light is much larger than the wavelength of electrons.
A) contrast
B) magnification
C) resolution
D) penetration

Answer 32

C) resolution

Electron microscopy’s shorter wavelengths enable much higher resolution than light microscopy.

Question 33

Which of the following types of microscopy is especially effective for viewing details of internal structures within live cells?
A) phase-contrast microscopy
B) transmission electron microscopy
C) bright-field microscopy
D) scanning electron microscopy

Answer 33

A) phase-contrast microscopy

Phase-contrast allows visualization of internal structures in live cells without staining.

Question 33

Which of the following types of microscopy could be used to visualize the layers of the cell membrane and the cell wall?
A) phase-contrast microscopy
B) transmission electron microscopy
C) bright-field microscopy
D) confocal microscopy

Answer 33

B) transmission electron microscopy

TEM offers sufficient resolution to visualize these fine details.

Question 34

Who was the first researcher to provide direct experimental data that supported the germ theory to explain infectious disease?
A) Pasteur
B) Winogradsky
C) Lister
D) Koch

Answer 34

D) Koch

Koch’s postulates provided the framework for linking specific microbes to specific diseases.

Question 35

When medical devices are left in the body, bacteria may grow on them as _______, which makes them especially resistant to treatment.
A) biofilms
B) liquids
C) populations
D) communities

Answer 35

A) biofilms

Biofilms are surface-attached communities of microbes that are more resistant to treatment.

Question 36

Microbes that live at high temperatures in hot springs are ______.
A) always Archaea.
B) also able to thrive at low temperatures.
C) called extremophiles.
D) rarely found.

Answer 36

C) called extremophiles.

Extremophiles thrive in extreme environments, including high temperatures.

Question 37

Which statement about the relationship between microbes and humans is FALSE?
A) Most microbes are pathogenic.
B) Infectious disease is an important public health concern.
C) Bacteria in the digestive tract are important for digestion.
D) Microbes in root nodules fix nitrogen and allow plants to make nitrogen-rich products.

Answer 37

A) Most microbes are pathogenic.

Only a small fraction of microbes are pathogenic to humans.

Question 38

Why is ribosomal RNA especially useful for the study of phylogenetic relationships?
A) It is only found in some species, helping to distinguish them from others.
B) It is highly conserved.
C) It is highly variable.
D) It is extremely short.

Answer 38

B) It is highly conserved.

The slow evolution of rRNA makes it useful for studying broad phylogenetic relationships.

Question 39

Why is it important to use cultivation-independent methods to help understand microbial diversity?
A) It allows researchers to identify species that cannot be grown in culture.
B) It is the only way that phylogenetic trees can be constructed.
C) It must be used after bacteria are cultured to more fully sequence their DNA.
D) It is necessary to be able to examine ribosomal RNA.

Answer 39

A) It allows researchers to identify species that cannot be grown in culture.

Many microbes are difficult or impossible to cultivate in the lab, making cultivation-independent methods essential for understanding microbial diversity.