NCLEX : Bacterial Physiology

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Example Questions

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Example Question #1 : Bacterial Physiology

Which of the following patients are most at risk for contracting a nosocomial infection?

Possible Answers:

A 55-year-old man with an asthma exacerbation

A 22-year-old mother in her third trimester

A 75-year-old woman receiving chemotherapy for colon cancer

A 60-year-old admitted with pancreatitis

A 10-year-old patient admitted for abdominal pain

Correct answer:

A 75-year-old woman receiving chemotherapy for colon cancer

Explanation:

A nosocomial infection is an infection that is transmitted from one person to another inside the hospital or other healthcare facility. It is often a result of healthcare workers failing to preform adequate hand hygiene and standard precautions. Those most at risk for infection are those who are immunocompromised (chemotherapy patients), those with breaks in skin integrity (wounds), and those with invasive devices (PICC lines, urinary catheters, invasive monitoring). 

Example Question #2 : Bacterial Physiology

Which of the following regarding pathogenic bacteria is false?

Possible Answers:

Pathogenic bacteria contain a protein envelope called a capsid

Some bacteria have cell walls

Pathogenic bacteria may secrete toxins that make the host ill

Many bacteria do not have flagella

Pathogenic bacteria may reproduce inside a host or human's own cells

Correct answer:

Pathogenic bacteria contain a protein envelope called a capsid

Explanation:

A pathogenic bacteria is a disease-causing bacteria. They may secrete toxins to make a host ill or reproduce inside the host's own cells. Bacteria may have cell walls, although some do not. Similarly, some bacteria may have flagella and others do not. It is typical for viruses to have a capsid (protein coat). Some viruses such as the human immunodefficiency virus (HIV) have envelopes, which makes it difficult for the immune system to detect and destroy them.  

Example Question #3 : Bacterial Physiology

Clostridium difficile is difficult to prevent in a hospital setting due to what feature?

Possible Answers:

Difficult to culture

Poor sanitation management

Endospore formation

Route of transmission

Correct answer:

Endospore formation

Explanation:

C. difficile is an endospore-forming bacteria. While in the endospore (or dormant) stage, C. difficile spores are highly resistant to disinfectants. This renders sterilization procedures less effective in a hospital setting and leads to a higher frequency of infection. While route of transmission and hospital sanitation are important factors in C. difficile transmission, it is their endospore formation that gives these bacteria a level of resistance above other fecal-oral species present in a hospital setting.

Example Question #4 : Bacterial Physiology

Antibiotics work exclusively against __________

Possible Answers:

Bacteria only

Fungi only

Viruses and bacteria

Viruses only

Correct answer:

Bacteria only

Explanation:

Antibiotics work exclusively against bacteria. They are not effective against fungal infections, and they are not effective against viruses such as influenza, rotovirus, or rhinovirus (the most frequent cause of the common cold). 

Example Question #5 : Bacterial Physiology

Conjugation between bacteria is carried out via what structure?

Possible Answers:

Pili

Cilia

Capsule

Flagella

Correct answer:

Pili

Explanation:

Pili are short, hairlike structures on the surface of some bacteria. Conjugative pili can form a sort of tube between bacterial cells, allowing for the transfer of DNA from one bacteria to another.

Flagella are whip-like structures that allows bacteria to move within a fluid medium. Cilia are hair-like structures found primarily on the surface of mammalian cells, but are also found on bacterial cells, where they aid in attachment. A bacterial capsule is a polysaccharide layer outside the cell envelope that does not take part in bacterial conjugation, and may secrete "slime" which protects the bacteria from the surrounding environment.

Example Question #6 : Bacterial Physiology

Which of the following terms describes the form of asexual reproduction in which a single-celled organism divides into two cells of the same size?

Possible Answers:

Conjugation

Binary fission

Meiosis

Mitosis

Correct answer:

Binary fission

Explanation:

The process of asexual reproduction in which a single-celled organism divides into two cells of the same size is called binary fission. This occurs among prokaryotes and is the primary method of reproduction in bacterial species. Mitosis and meiosis are forms of cell division among eukaryotic cells. Conjugation is not a method of bacterial reproduction; rather, it is a method by which joined bacteria may transmit DNA, especially genes on plasmids that confer resistance. 

Example Question #7 : Bacterial Physiology

Which of the following is found in greater quantity in Gram negative bacteria than in Gram positive bacteria?

Possible Answers:

Teichoic acid

Lipopolysaccharide

Peptidoglycan

Murein

Correct answer:

Lipopolysaccharide

Explanation:

Gram negative strains of bacteria possess more lipopolysaccharide than do Gram positive strains. This higher proportion of lipopolysaccharide lies on the exterior of Gram negative bacteria's outer membranes of their cell walls. Gram negative bacteria have significantly less peptidoglycan than do Gram positive strains, which accounts for their observable chromatic differences when using the Gram stain technique. Specifically, the this thin layer of peptidoglycan in Gram negative bacteria fails to retain crystal violet during Gram staining, especially after iodine is added, which acts as a mordant. Subsequent staining with safranin gives Gram negative bacteria a pink or light red color when viewed under a light microscope. Teichoic acid, present in Gram positive bacteria only, functions to increase the rigidity of the cell wall. Murein is another name for peptidoglycan.

Example Question #8 : Bacterial Physiology

Which of the following is found in prokaryotes and not eukaryotes?

Possible Answers:

Ribosomes

Mitochondria

Flagella

Plasmids

Correct answer:

Plasmids

Explanation:

Plasmids are found only in prokaryotes. In bacteria, they are transferred either via conjugation, transduction, or transformation. Both prokaryotes and eukaryotes contain ribosomes, however the subunits of eukaryotes are smaller (have a lower sedimentation rate). Both can contain flagella, but they differ in complexity and type of motion. Only eukaryotes contain mitochondria, which is the site of the Krebs cycle, beta-oxidation of fatty acids, and electron transport.

Example Question #9 : Bacterial Physiology

A bacterium has a generation time of 25 minutes. Starting with a single cell, how many cells are present in 200 minutes?

Possible Answers:

Correct answer:

Explanation:

This question involves the concept of generation time, which is the time it takes one colony to double. Therefore, there will be 2 cells in 25 minutes, 4 cells in 50 minutes, 8 cells in 75 minutes, 16 in 100 minutes, 32 cells in 125 minutes, 64 cells in 150 minutes, 128 cells in 175 minutes, and 256 cells in 200 minutes. Note that it is very rare for a single bacterium to be isolated, thus a bacterial colony grows exponentially over a short period of time. Note that 200 minutes represents 8 generation times. The number of bacteria, when starting with a single cell, can be calculated as  where  is the number of generation (doubling) times. Here, we have .

Example Question #10 : Bacterial Physiology

Which sterilization method is best for destroying endospores?

Possible Answers:

Oven

Autoclave

Pasteurization

Refrigeration

Correct answer:

Autoclave

Explanation:

Students should possess the knowledge that the Clostridium genus produces endospores. This fact makes them extremely virulent. Heating alone will not kill the spores. Only heat, accompanied by pressure, will penetrate spores. This method is obtained either by an autoclave or pressure cooker.

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