Question 1

This form of DNA is commonly found in eukaryotic cells.

Accepted Answer

Eukaryotic cells typically have linear DNA molecules, which are organized into linear chromosomes.

Question 2

Name the numerous short (3 to 10 μm) projections that extend from the cell surface and are used for cellular locomotion.

Accepted Answer

Cilia are numerous short (3 to 10 μm) projections that extend from the cell surface and are used for cellular locomotion. Flagella, on the other hand, are longer (up to 200 μm) projections typically found only on certain cells, such as sperm cells, and are used primarily for propulsion. Mitochondria are organelles involved in energy production, while phospholipids are a type of lipid molecule that make up cell membranes.

Question 3

What enables the microbiologist to select the correct media for primary culture and optimize the chance of isolating a pathogenic organism?

Accepted Answer

Understanding the growth requirements of potential pathogens at specific body sites is critical in selecting the appropriate media for primary culture. This knowledge can optimize the chances of isolating a pathogenic organism as different organisms have different nutritional and growth requirements. For example, some bacteria may require specific nutrients such as blood or bile, while others may grow better under aerobic or anaerobic conditions.

Question 4

In the laboratory, the clinical microbiologist is responsible for all the following, except

Accepted Answer

While the clinical microbiologist may provide guidance on treatment options based on identified microorganisms, they are not ultimately responsible for selecting treatments for patients. This falls within the scope of the patient's physician or healthcare provider.

Question 5

Diagnostic microbiologists apply placement and naming of bacterial organisms into all the following categories, except

Accepted Answer

Diagnostic microbiologists do not apply placement of bacterial organisms into the category of order, as this is a higher taxonomic level and is typically used in the classification of more complex organisms, such as plants and animals. Bacteria are classified primarily based on their genetic and phenotypic characteristics at the levels of family, genus, and species.

Question 6

The function of a cell wall is to

Accepted Answer

The function of a cell wall is to provide rigidity and strength to the exterior of the cell. This is particularly important in organisms like plants and bacteria, where the cell wall helps to maintain the cell's shape and prevent it from bursting as a result of internal pressure. The cell wall also serves as a protective barrier against pathogens and other external threats. However, cell walls do not typically regulate the transport of macromolecules in and out of the cell, provide reserve energy, or protect the eukaryote from predators, so choices A, C, and D are incorrect.

Question 7

A microbiology technologist performs a traditional bacterial stain on a colony from a wound culture that is suspected to contain bacteria from the genus Clostridium. The unstained areas in the bacterial cell observed by the technologist are called

Accepted Answer

Endospores are resistant, dormant structures that form within certain bacterial cells, including those of the genus Clostridium. They are highly resistant to staining, which is why they appear as unstained areas in traditional bacterial stains. Cilia and mitochondria are not found in bacterial cells, and ribosomes are not typically visible using traditional stains.

Question 8

A microorganism that is a unicellular organism and lacks a nuclear membrane and true nucleus belongs to which classification?

Accepted Answer

Bacteria are unicellular organisms that lack a nuclear membrane and true nucleus. Fungi, algae, and parasites are all eukaryotic organisms with a well-defined nucleus and nuclear membrane.

Question 9

A clinical laboratory scientist is working on the bench, reading plates, and notices that a culture has both a unicellular form and a filamentous form. What type of organism exhibits these forms?

Accepted Answer

Fungi are known to exhibit both unicellular (yeast) and filamentous (mold) forms. Viruses, bacteria, and parasites typically do not exhibit these forms.

Question 10

The nuclear membrane in prokaryotes is

Accepted Answer

Prokaryotes, such as bacteria, do not have a nucleus or a nuclear membrane. Instead, their genetic material is contained within the cytoplasm.

Question 11

What structure is described as a phospholipid bilayer embedded with proteins and sterols that regulates the type and amount of chemicals that pass in and out of a cell?

Accepted Answer

The phospholipid bilayer embedded with proteins and sterols that regulates the type and amount of chemicals that pass in and out of a cell is called the plasma membrane. The other options listed (cell wall, mitochondria, and endoplasmic reticulum) are all structures found within a cell, but do not fit the description given in the question.

Question 12

To survive, microbial inhabitants have learned to adapt by varying all of the following, except

Accepted Answer

Bacteria have a fixed shape which is determined by their cell wall structure, and cannot vary it to adapt. However, they can adjust their growth rate, atmospheric requirements, and temperature preferences to survive in different environments.

Question 13

All of the following statements are true about viruses, except:

Accepted Answer

Viruses cannot survive or reproduce without a host cell, therefore option D is not true. Options A, B, and C are true statements about viruses.

Question 14

What makes the interior of the plasma membrane potentially impermeable to water-soluble molecules?

Accepted Answer

The hydrophobic tails of the phospholipid molecules are found in the interior of the plasma membrane, creating a hydrophobic barrier that prevents water-soluble molecules from passing through easily. This property of the plasma membrane is often referred to as selective permeability.

Question 15

Bacterial species that exhibit phenotypic differences are considered

Accepted Answer

Bacterial species that exhibit phenotypic differences may be classified as subspecies, which is a taxonomic rank below the level of species. Biovarieties are different strains of a species that differ in metabolic or physiological characteristics, while serovarieties are strains that possess different antigenic properties. Phagevarieties are strains that have different susceptibility to infection by bacteriophages.

Question 16

Prokaryotic cells have which of the following structures in their cytoplasm?

Accepted Answer

Prokaryotic cells lack membrane-bound organelles such as the Golgi apparatus, mitochondria, and endoplasmic reticulum. However, they do have ribosomes in their cytoplasm, which are responsible for protein synthesis.

Question 17

This constituent of a gram-positive cell wall absorbs crystal violet but is not dissolved by alcohol, thus giving the gram-positive cell its characteristic purple color.

Accepted Answer

Peptidoglycan is a major component of the gram-positive cell wall and is responsible for retaining the crystal violet stain during the gram staining process. It is not dissolved by alcohol, which allows the cell to remain purple in color. Mycolic acid is found primarily in the cell wall of mycobacteria, which are acid-fast bacteria and are not typically stained using the gram technique. Cholesterol is a component of eukaryotic cell membranes and is not found in the cell walls of bacteria. Carbolfuchsin is a stain used in acid-fast staining methods and is not used in the gram staining technique.

Question 18

When performing a Gram stain on a gram-negative organism, the crystal violet is absorbed into this outer cell wall layer, and then washed away with the acetone alcohol. What is the main component of the outer layer of the cell wall?

Accepted Answer

Lipopolysaccharide is the main component of the outer layer of the cell wall in gram-negative organisms. This component is responsible for the negative charge and endotoxin activity associated with these bacteria. Peptidoglycan is found in both gram-positive and gram-negative bacteria, while mycolic acid and N-acetyl-D-muramic acid are specific to certain bacterial groups (e.g. mycobacteria and gram-positive bacteria, respectively).

Question 19

Mycobacteria have a gram-positive cell wall structure with a waxy layer containing these two compounds.

Accepted Answer

Mycobacteria have a unique cell wall structure that includes a waxy layer made up of glycolipids and mycolic acid, which gives them their characteristic acid-fast staining property. Lipopolysaccharides are found in the outer membrane of gram-negative bacteria, not in the cell wall of mycobacteria, and phospholipids are present in all bacteria, not just mycobacteria.

Question 20

Who was considered the father of protozoology and bacteriology?

Accepted Answer

Anton van Leeuwenhoek is considered the father of protozoology and bacteriology because he was the first to observe and describe microscopic organisms, including protozoa and bacteria, and he discovered many new species.

Quiz 1: Bacterial Cell Structure, Physiology, Metabolism, and Genetics