What instruments are used to perform sterile transfer from one medium to another
Loop & needle
Loop & syringe
needle & syringe
all above are true
The Correct Answer is A
A. Loop & needle: In microbiology, a sterile inoculating loop or needle is commonly used to transfer microorganisms from one culture medium to another while maintaining aseptic technique. Loops are typically used for streaking or spreading bacteria on agar, while needles are used for stabbing into agar or transferring small amounts of culture into broth, allowing precise and sterile handling.
B. Loop & syringe: Syringes are generally not used for routine transfer of microbial cultures between media because they increase the risk of contamination and are more appropriate for measuring or injecting liquids rather than streaking or inoculating media.
C. Needle & syringe: Needles with syringes are mainly used in clinical or laboratory procedures for injecting liquids or drawing samples. They are not standard instruments for sterile transfer between culture media in microbiology because they are less precise for streaking or isolating colonies.
D. all above are true: Only the loop and needle are routinely used for sterile transfers in microbiology. Syringes are not standard instruments for transferring cultures between media, so this option is incorrect.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
A. To differentiate between Gram-positive and Gram-negative bacteria: Differentiating Gram-positive from Gram-negative bacteria is the purpose of Gram staining, a differential staining technique. Simple staining does not distinguish between bacterial cell wall characteristics or species based on Gram reaction.
B. To determine bacterial motility: Bacterial motility is assessed using methods such as the hanging drop technique or motility agar. Simple staining does not provide information about motility because it stains all cells uniformly and immobilizes them on the slide.
C. To visualize the size, shape, and arrangement of bacteria: The primary purpose of simple staining is to enhance the contrast between bacterial cells and the background, allowing clear observation of cellular morphology, including size, shape (cocci, bacilli, spirilla), and arrangement (chains, clusters, pairs). This information is fundamental for bacterial identification and classification in microbiology.
D. To identify bacterial endospores: Endospore identification requires special staining techniques, such as the Schaeffer-Fulton method using malachite green and safranin. Simple staining cannot differentiate spores from vegetative cells because all structures take up the basic dye similarly.
Correct Answer is B
Explanation
A. Enzymes that inhibit bacterial growth: Hemolysins do not inhibit bacterial growth; instead, they act on host cells. They are not antimicrobial agents but rather virulence factors that facilitate bacterial survival and spread within the host.
B. Toxins that lyse red blood cells: Hemolysins are exotoxins produced by certain bacteria, such as Streptococcus and Staphylococcus species. They disrupt the membrane of red blood cells, causing hemolysis and releasing hemoglobin. This action provides bacteria with access to nutrients, particularly iron, which is essential for their metabolism and pathogenicity.
C. Structural proteins in bacterial capsules: Capsules are composed of polysaccharides or proteins that protect bacteria from phagocytosis. Hemolysins are not structural components of capsules; they are secreted proteins that damage host cells rather than forming protective layers around the bacterium.
D. Antibiotic resistance factors: Hemolysins do not confer resistance to antibiotics. Antibiotic resistance factors include enzymes such as beta-lactamases or efflux pumps that prevent drugs from killing the bacteria. Hemolysins function solely as cytotoxins targeting host cells.
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