Answer to Question 1
Correct Answer: 1
Rationale 1: Antibiotic selective toxicity allows pathogens to be killed or their growth severely hampered without major effects on human cells.
Rationale 2: Selective synthesis is not an action of antibiotics.
Rationale 3: Bacteriostatic action is the ability of the antibiotic to halt bacterial growth.
Rationale 4: Opportunistic action is the ability of a pathogen to invade a host that is immunocompromised.
Global Rationale: Antibiotics exert selective toxicity by targeting these unique differences between human and bacterial, fungal, and protozoan cells. Through this selective action, these pathogens can be killed, or their growth severely hampered, without any major effects on human cells.
Answer to Question 2
Correct Answer: 1
Rationale 1: Gram-negative cocci are round with thin cell walls.
Rationale 2: Gram-positive bacteria have thick walls.
Rationale 3: Bacilli are rod shaped.
Rationale 4: Spirilla are spiral shaped.
Global Rationale: Bacteria are often described by their basic shape, which can be readily determined microscopically. Those with rod shapes are called bacilli, those that are spherical are called cocci, and those that are spiral are called spirilla. One of the simplest methods of classifying microbes is to examine them microscopically after a crystal violet Gram stain has been applied to the microbes. Bacteria that have thinner cell walls will lose the violet stain and are called gram negative.
Human sex chromosomes
Human embryonic stem cells forming rosettes, a sign of neural differentiation
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Hormones and their target cells.
Maternal age is the major risk factor for autosomal trisomies of all types. By age 42, about one in