Gram-positive bacteria appear purple because they contain:
Thick peptidoglycan layer
Outer membrane
Lipopolysaccharide
The Correct Answer is A
A. Thick peptidoglycan layer: Gram-positive bacteria have a thick, multilayered peptidoglycan cell wall that retains the crystal violet-iodine complex during the Gram staining process. This dense layer prevents the dye from being washed out during the alcohol decolorization step, causing Gram-positive bacteria to appear purple under a microscope.
B. Outer membrane: The outer membrane is characteristic of Gram-negative bacteria, not Gram-positive bacteria. It contains lipopolysaccharides and provides an additional barrier but does not contribute to the retention of crystal violet in Gram-positive organisms.
C. Lipopolysaccharide: Lipopolysaccharides (LPS) are components of the outer membrane of Gram-negative bacteria and play a role in pathogenicity and immune activation. LPS is absent in Gram-positive bacteria and therefore does not influence their purple coloration during Gram staining.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
A. sanitization: Sanitization refers to the process of reducing microbial populations on inanimate objects to levels considered safe by public health standards. It lowers the risk of infection but does not necessarily destroy all vegetative pathogens.
B. degermation: Degermation, also called degerming, is the mechanical removal of microbes from a surface, typically the skin, using friction and antiseptics. It reduces microbial load but does not fully destroy pathogens and is mainly used for living tissues.
C. disinfection: Disinfection is the use of physical (e.g., heat) or chemical agents to destroy vegetative pathogens on inanimate objects. It effectively eliminates most pathogenic microorganisms, though it may not destroy bacterial spores. Disinfection is commonly used for medical equipment, surfaces, and instruments that do not require sterilization.
D. sterilization: Sterilization is a process that destroys all forms of microbial life, including spores. It is more extreme than disinfection and is used for surgical instruments and other items that must be completely free of microorganisms.
E. antisepsis: Antisepsis refers to the application of chemical agents to living tissues to inhibit or destroy microorganisms. Unlike disinfection, antisepsis is safe for skin and mucous membranes but may not completely eliminate all pathogens.
Correct Answer is A
Explanation
A. Budding: Yeasts, which are unicellular fungi, primarily reproduce asexually through budding. In this process, a small protuberance forms on the parent cell, grows, and eventually detaches to become a new independent cell. Budding allows rapid population growth and is a hallmark characteristic of organisms like Saccharomyces cerevisiae.
B. Binary fission: Binary fission is the primary method of reproduction for most prokaryotic organisms, such as bacteria, in which a single cell divides into two genetically identical daughter cells. While yeasts can undergo mitotic divisions, budding is their main asexual reproductive mechanism.
C. Conjugation: Conjugation is a form of genetic recombination seen in some bacteria and protozoa, involving the transfer of genetic material between two cells. Yeasts generally do not use conjugation as their primary reproductive strategy, although sexual reproduction via mating types can occur under certain conditions.
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