Test 1: Chapters 1, 2, and 4

Question 1

Select the statements that accurately reflect characteristics of water molecules (select all that apply):

A. It is a nonpolar molecule
B. Polar covalent bonds are found between hydrogen and oxygen within a water molecule.
C. The atoms within a molecule of water exhibit ionic bonding.
D. Hydrogen bonds are found between different water molecules.
E. Electrons are shared between the oxygen and hydrogen atoms within a molecule of water.

Answer 1

B. Polar covalent bonds are found between hydrogen and oxygen within a water molecule.
D. Hydrogen bonds are found between different water molecules.
E. Electrons are shared between the oxygen and hydrogen atoms within a molecule of water.

Reason: The oxygen atom in water is bonded to each of two hydrogen atoms by polar covalent bonds, in which electrons are unequally shared. Because of this unequal sharing of electrons, the hydrogen atoms of one water molecule have a partial positive charge and are attracted to the partial negative charge of an oxygen atom in a different water molecule. This attraction between different water molecules is called hydrogen bonding.

Question 2

Select the structures that are possessed by some, but not all, bacteria (select all that apply):

A. Flagella
B. Cell membrane
C. Endospores
D. Ribosomes
E. Pili
F. Fimbriae
G. Glycocalyx

Answer 2

A. Flagella
C. Endospores
E. Pili
F. Fimbriae
G. Glycocalyx

Reason: Some, but not all, bacteria have flagella, endospores, pili, fimbriae, and a glycocalyx. All bacteria have a cell membrane and ribosomes.

Question 3

Select all of the correct statements below, comparing and contrasting inorganic and organic molecules (select all that apply):

A. If a molecule contains carbon, it is organic.
B. If a molecule contains carbon and hydrogen, it is inorganic.
C. Living things are composed of mostly organic molecules.
D. Carbon is an important molecule in living things because of its ability to covalently bond to up to four different atoms.
E. All four types of macromolecules are organic compounds.
F. The human body never contains inorganic compounds because carbon is the fundamental unit of life and inorganic compounds do not contain carbon.

Answer 3

C. Living things are composed of mostly organic molecules.
D. Carbon is an important molecule in living things because of its ability to covalently bond to up to four different atoms.
E. All four types of macromolecules are organic compounds.

Reason: Compounds with both carbon and hydrogen are called organic. All others are inorganic. For examples, carbon dioxide (CO2) is inorganic, whereas glucose (C6H12O6) is organic. Carbon has four electrons in its valence shell and therefore, it can easily bond to other atoms by sharing those electrons in a covalent bond. This makes it an important part of the building blocks of life, such as the four types of macromolecules (lipids, carbohydrates, nucleic acids, and proteins). Living things are mostly made up of these organic building blocks, but do contain inorganic compounds as well. Simple examples include respiratory gases such as CO2 and O2.

Question 4

The term used to describe a cluster of circular bacteria is:

A. streptobacilli
B. streptococci
C. vibrio
D. staphylococci

Answer 4

D. staphylococci

Reason: Staphylococci is the term used to describe a cluster of spherical bacteria.

Question 5

Select the main groups of macromolecules found in living things (select all that apply):

A. Nucleic acids
B. Oxygen compounds
C. Lipids
D. Proteins
E. Carbohydrates

Answer 5

A. Nucleic acids
C. Lipids
D. Proteins
E. Carbohydrates

Reason: The four main groups of macromolecules in living things are carbohydrates, lipids, proteins, and nucleic acids. While oxygen and carbon dioxide are important molecules in living things, they are not considered macromolecules.

Question 6

Select characteristics exhibited by all bacteria (select all that apply):

A. Chromosome
B. Fimbriae
C. Capsule
D. Ribosomes
E. Cell wall
F. Flagella
G. Endospores
H. Cell membrane

Answer 6

A. Chromosome
D. Ribosomes
H. Cell membrane

Reason: All bacteria possess a cell membrane, a chromosome, and ribosomes. Almost all bacteria possess a cell wall with the exception of a group of bacteria known as the mycoplasmas or bacteria that have been exposed to penicillin or lysozyme. Many, but not all bacteria have fimbriae, flagella, and endospores.

Question 7

As a major component of gram-negative outer membranes, lipopolysaccharide can stimulate shock and fever and its lipid portion is referred to as:

A. endotoxin
B. glycosphingolipid
C. phospholipid
D. exotoxin

Answer 7

A. endotoxin

Reason: The outer membrane of gram-negative envelopes contains lipopolysaccharide, also known as LPS. The lipid portion of lipopolysaccharide can cause fever and shock and is also known as endotoxin.

Question 8

Microorganisms are best defined as organisms that:

A. cause human disease
B. lack a cell nucleus
C. are infectious particles
D. can only be found growing in laboratories
E. are too small to be seen with the unaided eye

Answer 8

E. are too small to be seen with the unaided eye

Question 9

All atoms in an element have the same number of protons.

A. True
B. False

Answer 9

A. True

Reason: All atoms of an element have the same number of protons and will exhibit the same chemical properties. The number of neutrons may vary if there are different isotopes of the element. The number of electrons can vary as well, creating ions of that same element.

Question 10

Which of the following is/are prone to biofilm accumulation?

A. Catheters
B. All of the choices are correct
C. Teeth
D. Artificial heart valves

Answer 10

B. All of the choices are correct

Reason: All these structures are prone to biofilm accumulation.

Question 11

All bacteria can be classified as either gram-positive or gram-negative.

A. True
B. False

Answer 11

B. False

Reason: Some bacteria are classified as acid-fast, and others lack cell walls completely.

Question 12

When ethanol is applied correctly, gram-positive cells appear _________ and gram-negative cells appear _________.

A. colorless; purple
B. purple; colorless
C. pink/red; purple
D. purple; pink/red

Answer 12

B. purple; colorless

Reason: Only gram-negative cells lose their purple color after ethanol is used as a decolorizer.

Question 13

Which of the following is true of biofilms?

A. They can lead to systemic infections
B. They pose no risk to the health of hospital patients
C. They exhibit the same gene
D. None of the choices are correct

Answer 13

A. They can lead to systemic infections

Reason: Bacteria exhibit a unique pattern of gene expression when in a biofilm, resulting in new growth characteristics. Biofilm bacteria can adhere to medical equipment used in patient care, such as a catheter, leading to the potential possibility of entering the patient’s body and causing a systemic infection.

Question 14

Select all of the characteristics of fimbriae (select all that apply):

A. Allow bacterial cells to colonize host tissues
B. Hollow tubes for material exchange
C. Allow bacterial cells to avoid phagocytosis
D. Short appendages
E. Participate in biofilm formation

Answer 14

A. Allow bacterial cells to colonize host tissues
B. Hollow tubes for material exchange
C. Allow bacterial cells to avoid phagocytosis
D. Short appendages

Reason: Fimbriae are short appendages that aid the bacterium in attachment, allowing for colonization and biofilm formation.

Question 15

The majority of oxygen in earth’s atmosphere is a product of photosynthesis by:

A. green plants
B. agricultural lands
C. microorganisms
D. rain forests

Answer 15

C. microorganisms

Question 16

What general type of stain is used to separate types of bacteria based on their cellular structures?

A. Simple
B. Negative
C. Acidic
D. Differential

Answer 16

D. Differential

Reason: Differential staining techniques can be used to identify different types of bacteria, based on structures like their cell wall or the presence of endospores.

Question 17

Biofilms are often more sensitive to antibiotics:

A. True
B. False

Answer 17

B. False

Reason: Biofilms are often impervious to antibiotics.

Question 18

During bacterial conjugation, DNA can be transferred from the donor cell to the recipient cell because a/an __________ connects the two cells.

A. fimbria
B. axial filament
C. flagellum
D. pilus

Answer 18

D. pilus

Reason:
DNA can be transferred when two bacteria are connected by a hollow tube known as a pilus (pleural – pili) during bacterial conjugation.

Question 19

Why must fresh cells be used when performing a Gram stain?

A. All of these are reasons why fresh cells must be used for Gram staining.
B. Fresh cells do not smell as badly as older cells.
C. Old cells may not Gram stain properly.
D. As cells age, they won’t stick to the slide.

Answer 19

C. Old cells may not Gram stain properly.

Question 20

Bacteria are larger than human cells:

A. True
B. False

Answer 20

B. False

Reason: Bacteria are much smaller than eukaryotic cells.

Question 21

Bacteria are only visible with an electron microscope:

A. True
B. False

Answer 21

B. False

Reason: Bacteria are visible with the light microscope.

Question 22

Using microbes to detoxify a site contaminated with heavy metals is an example of:

A. bioremediation
B. immunology
C. decomposition
D. biotechnology
E. epidemiology

Answer 22

A. bioremediation

Question 23

What does the capsule typically look like on a stained smear when viewing under the light microscope?

A. Colored layers of threadlike structures surrounding the cell
B. Clear halos around the cells
C. Dark circles surrounding the cell wall

Answer 23

B. Clear halos around the cells

Reason: The capsule is usually resistant to dyes. Therefore, most staining methods that show the capsule will stain the cells and the background of the smear, leaving the capsules as clear halos around each cell.

Question 24

The smallest and most significant taxon is a:

A. phylum
B. species
C. family
D. kingdom
E. genus

Answer 24

B. species

Question 25

Choose the phrase that describes what will happen to pH as hydrogen ion concentration increases:

A. pH will increase
B. pH will decrease
C. pH will not change

Answer 25

B. pH will decrease

Reason: As hydrogen ion concentration increases, the pH will decrease. The higher the hydrogen ion concentration is in a solution, the lower the pH and the more acidic a solution will be.

Question 26

The bacterial flagellum moves the cell forward during _________, and the cell spins around during _________.

A. tumbles; runs
B. beating; rotating
C. positive rotations; negative rotations
D. runs; tumbles
E. negative rotations; positive rotations

Answer 26

D. runs; tumbles

Question 27

Analyze the following statements, and select those that correctly reflect the characteristics of archaea (select all that apply):

A. Bacteria and archaea are both classified into Kingdom Monera because they share the same cell wall chemistry; i.e., they all contain peptidoglycan.
B. Archaea are genetically more similar to bacteria than to eukaryotes.
C. The extreme halophiles are not only tolerant to high salt levels; they require it to grow.
D. Metabolically, archaea are the most diverse group of organisms on the planet, surviving in extreme conditions such as extreme heat, high salt levels, extreme pH, and high pressure.
E. Archaea are strictly environmental microbes; they are not part of the normal biota of higher organisms.

Answer 27

C. The extreme halophiles are not only tolerant to high salt levels; they require it to grow.
D. Metabolically, archaea are the most diverse group of organisms on the planet, surviving in extreme conditions such as extreme heat, high salt levels, extreme pH, and high pressure.

Question 28

You are preparing a solution by mixing 10 grams of glucose into distilled water. In this solution, distilled water is the:

A. precipitate
B. solvent
C. ion
D. solute

Answer 28

B. solvent

Reason: In this solution, water is the dissolving medium or solvent. Glucose is the solute. Water is the most common solvent in biological systems.

Question 29

What type of macromolecule makes up the bacterial capsule?

A. Proteins
B. Carbohydrates
C. Lipids
D. Nucleic acids

Answer 29

B. Carbohydrates

Reason: The capsule is made of polysaccharides, a complex type of carbohydrate.

Question 30

What component provides for a stronger cell wall structure in gram-positive cells in comparison to gram-negative cells?

A. Phospholipids
B. Outer membrane
C. Thick peptidoglycan layer
D. Teichoic acids
E. Lipopolysaccharide

Answer 30

C. Thick peptidoglycan layer

Reason: It is the thickness of the peptidoglycan layer that makes gram-positive cell walls stronger than gram-negative cells walls. The teichoic acids in gram-positive cell walls do not significantly contribute to the strength of the cell wall. Both cell types have phospholipids in their cell membrane. Gram-positive cells do not have an outer membrane or lipopolysaccharide.

Question 31

Select all of the structures that are found in a gram-positive cell envelope (select all that apple):

A. Thick layer of peptidoglycan
B. Outer membrane
C. Cell membrane
D. Teichoic acids
E. Lipopolysaccharide
F. Lipoteichoic acids
G. Thin layer of peptidoglycan

Answer 31

A. Thick layer of peptidoglycan
C. Cell membrane
D. Teichoic acids
F. Lipoteichoic acids

Reason: The structures found in a gram-positive cell envelope include the cell membrane, a thick layer of peptidoglycan, and a combination of teichoic acids and lipoteichoic acids. The outer membrane, cell membrane, a thin layer of peptidoglycan, and lipopolysaccharide are found in gram-negative cell envelopes.

Question 32

Alpha helices and beta pleated sheets are examples of the __________ level of protein structure.

A. tertiary
B. secondary
C. quaternary
D. primary

Answer 32

B. secondary

Reason: There are four levels of protein structure. Alpha helices and beta pleated sheets are two different forms of secondary structure, which form due to hydrogen bonding between functional groups on the amino acids that make up the primary chain.

Question 33

The thinner peptidoglycan layer of gram-positive bacteria allows the crystal-violet-iodine complex to leave the cell.

A. True
B. False

Answer 33

B. False

Reason: Gram-positive bacteria have a thicker peptidoglycan layer that traps the crystal-violet-iodine complex inside the cell.

Question 34

What condition most commonly triggers sporogenesis among endospore-forming bacteria?

A. Nutrient depletion
B. Presence of toxic chemicals
C. Lack of water
D. Excess heat
E. Ultraviolet light exposure

Answer 34

A. Nutrient depletion

Reason: Sporogenesis (endospore formation) is triggered within a vegetative cell by nutrient depletion, particularly the depletion of carbon or nitrogen.

Question 35

Select the components of ATP (Select all that apply):

A. Ribose
B. Adenine
C. Phosphate
D. Deoxyribose

Answer 35

A. Ribose
B. Adenine
C. Phosphate

Reason: ATP is a ribonucleotide, containing ribose, adenine, and three phosphates. There is no deoxyribose in ATP.

Question 36

A cell contains a fertility (F) plasmid that allows it to produce a structure for exchanging DNA with another cell. What structure is coded for by the genes of this plasmid?

A. Capsule
B. Fimbria
C. Pilus
D. Flagellum

Answer 36

C. Pilus

Reason: A pilus is a hollow tube allowing for DNA exchange between cells.

Question 37

Place this in order, starting with the first step:

A. Safranin is applied to stain the colorless gram-negative cells.
B. Gram’s iodine, which complexes with the purple crystal violet molecules is added.
C. The addition of crystal violet, where both cell types take up the purple dye.
D. Alcohol is added and removes the purple dye molecules from the thin peptidoglycan layer of the gram-negative cells only.

Answer 37

C. The addition of crystal violet, where both cell types take up the purple dye.
B. Gram’s iodine, which complexes with the purple crystal violet molecules is added.
D. Alcohol is added and removes the purple dye molecules from the thin peptidoglycan layer of the gram-negative cells only.
A. Safranin is applied to stain the colorless gram-negative cells.

Question 38

After Gram’s iodine is added, what color do the cells appear under a light microscope?

A. All cells appear colorless
B. Some cells may be purple and some may be pink/red
C. All cells appear purple
D. All cells appear pink/red

Answer 38

C. All cells appear purple

Reason: After iodine is added to a smear, all the cells appear purple.

Question 39

Endospores are reproductive structures produced by multiple bacterial cell divisions, with one vegetative cell producing many endospores:

A. True
B. False

Answer 39

B. False

Endospores are not reproductive structures. One vegetative cell will form one endospore. When the spore is released, the vegetative cell (sporangium) is lysed. When the endospore germinates, it will form one vegetative cell.

Question 40

The term used to describe a gently curved bacterium is:

A. spirochete
B. coccobacillus
C. vibrio
D. streptobacillus

Answer 40

C. vibrio

Reason: Vibrio is the term used to describe bacteria that are shaped like a comma, or a gently curved bacterium.

Question 41

If the Gram’s iodine step was skipped in this technique, what would likely be seen under the microscope?

A. Most cells would appear blue.
B. All cells would appear colorless.
C. Most cells would appear red/pink.
D. Most cells would appear purple.

Answer 41

C. Most cells would appear red/pink.

Reason: The iodine forms a complex with the purple dye molecules, helping it stick in the thick gram-positive cell wall. Without it, the alcohol would most likely wash the crystal violet from all cells, and they would stain pink/red in the last step.

Question 42

The scientific method is used by scientists to explain a certain natural phenomenon, and it involves the formation of a __________ as a tentative explanation of the observed or measured phenomenon.

A. experiment
B. hypothesis
C. theory
D. variable

Answer 42

B. hypothesis

Reason: Science is a process of investigation, using observation, experimentation, and reasoning. The scientific method is a process for investigating events or phenomena around us, and the investigation starts with the formulation of a hypothesis or a supposition of why the event occurred.

Question 43

Biofilms typically do not develop on healthy tissue:

A. True
B. False

Answer 43

A. True

Reason: Biofilms tend to accumulate on damaged tissues.

Question 44

Choose the term that describes the overall system of discovering, arranging, and naming organisms:

A. Classification
B. Hierarchy
C. Nomenclature
D. Identification
E. Taxonomy

Answer 44

E. Taxonomy

Question 45

Which external structure directly impacts the effectiveness of the host immune system?

A. Capsule
B. Pilus
C. Flagellum
D. Fimbria

Answer 45

A. Capsule

Reason: The capsule allows a bacterium to avoid phagocytosis by white blood cells, therefore evading a major host immune defense.

Question 46

Which of these pairs is incorrectly matched?

A. Pilus–attachment
B. Flagellum–motility
C. Capsule–protective layer
D. Fimbriae–motility

Answer 46

D. Fimbriae–motility

Reason: Fimbriae are involved in attachment, not motility.

Question 47

A hypothesis must be tested many times before it can be considered a theory:

A. True
B. False

Answer 47

A. True

Question 48

Which of the following are not considered microorganisms?

A. Fungi
B. Viruses
C. Mosquitoes
D. Protozoa
E. Bacteria

Answer 48

C. Mosquitoes

Question 49

The presence of flagella can be determined by a Gram stain.

A. True
B. False

Answer 49

B. False

Reason: Special stains are needed to visualize flagella.

Question 50

Select the components of DNA to test your understanding of nucleotide composition (select all that apply):

A. Amino acids
B. Phosphate
C. Deoxyribose
D. Nitrogen bases
E. Fatty acids

Answer 50

B. Phosphate
C. Deoxyribose
D. Nitrogen bases

Reason: Nucleic acids are polymers of nucleotides. Nucleotides are composed of phosphate, a pentose sugar (deoxyribose in DNA and ribose in RNA), and nitrogenous bases. There are no amino acids and no fatty acids in nucleic acids.

Question 51

The differential stage of the Gram stain is the application of:

A. crystal violet
B. ethanol
C. safranin
D. iodine

Answer 51

B. ethanol

Reason: Ethanol is the first step in the staining process that shows differences between the two types of bacteria. After its application, the gram-positive bacteria will be purple, and the gram-negative bacteria will be colorless.

Question 52

Rod-shaped bacteria:

A. are all gram-negative.
B. are never gram-positive or gram-negative.
C. can be either gram-positive or gram-negative.
D. are all gram-positive.

Answer 52

C. can be either gram-positive or gram-negative.

Reason: Rod-shaped bacteria can be gram-positive, gram-negative, or acid-fast.

Question 53

Select characteristics exhibited by all cells (select all):

A. Cytoplasmic membrane
B. Nucleus
C. DNA
D. Ribosomes
E. Cell wall
F. Organelles

Answer 53

A. Cytoplasmic membrane
C. DNA
D. Ribosomes

Reason: All cells (bacteria, archaea, and eukaryotic cells) have a cytoplasmic membrane, DNA (chromosome), ribosomes, and cytoplasm. Bacterial and archaeal cells lack a nucleus and organelles. Animal cells and some protists lack a cell wall.

Question 54

Astrobiology is considered a sub-discipline of microbiology because:

A. all extraterrestrials known are microbial
B. only microbes can reproduce under the extreme conditions in outer space
C. life elsewhere in the universe is likely to be microbial
D. microbes are known to exist on other planets

Answer 54

C. life elsewhere in the universe is likely to be microbial

Question 55

Which of the following statements about flagellar structure is TRUE?

A. The hook anchors the flagellum in the cell membrane.
B. The basal body is a short curved segment.
C. The filament extends out of the cell.
D. The hook anchors the flagellum in the cell membrane and the basal body is a short curved segment.
E. The hook anchors the flagellum in the cell membrane, the basal body is a short curved segment, and the filament extends out of the cell.

Answer 55

C. The filament extends out of the cell.

Question 56

Select all of the structures that are found in a gram-negative cell envelope (select all that apply):

A. Thick layer of peptidoglycan
B. Outer membrane
C. Periplasmic space
D. Cell membrane
E. Teichoic acids
F. Lipopolysaccharide
G. Lipoteichoic acids
H. Thin layer of peptidoglycan

Answer 56

B. Outer membrane
C. Periplasmic space
D. Cell membrane
F. Lipopolysaccharide
H. Thin layer of peptidoglycan

Reason: The outer membrane, periplasmic space, lipopolysaccharide, cell membrane, and thin layer of peptidoglycan are found in gram-negative cell envelopes. The structures found in a gram-positive cell envelope include the cell membrane, a thick layer of peptidoglycan, and a combination of teichoic acids and lipoteichoic acids.