Q: Bacteria may become untreatable if they develop what in response to multiple antibiotics? Read this paragraph and choose the correct option from the provided answers: Evasion of the Immune System by Pathogens It is important to keep in mind that although the immune system has evolved to be able to control many pathogens, pathogens themselves have evolved ways to evade the immune response. An example already mentioned is in Mycobactrium tuberculosis, which has evolved a complex cell wall that is resistant to the digestive enzymes of the macrophages that ingest them, and thus persists in the host, causing the chronic disease tuberculosis. This section briefly summarizes other ways in which pathogens can "outwit" immune responses. But keep in mind, although it seems as if pathogens have a will of their own, they do not. All of these evasive "strategies" arose strictly by evolution, driven by selection. Bacteria sometimes evade immune responses because they exist in multiple strains, such as different groups of Staphylococcus aureus. aureus is commonly found in minor skin infections, such as boils, and some healthy people harbor it in their nose. One small group of strains of this bacterium, however, called methicillin-resistant Staphylococcus aureus, has become resistant to multiple antibiotics and is essentially untreatable. Different bacterial strains differ in the antigens on their surfaces. The immune response against one strain (antigen) does not affect the other; thus, the species survives. Another method of immune evasion is mutation. Because viruses' surface molecules mutate continuously, viruses like influenza change enough each year that the flu vaccine for one year may not protect against the flu common to the next. New vaccine formulations must be derived for each flu season. Genetic recombinationthe combining of gene segments from two different pathogensis an efficient form of immune evasion. For example, the influenza virus contains gene segments that can recombine when two different viruses infect the same cell. Recombination between human and pig influenza viruses led to the 2010 H1N1 swine flu outbreak. Pathogens can produce immunosuppressive molecules that... Choices: - affinity - weakness - acceptance - resistance A:
resistance
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Q: What is the basic unit of computer memory? Read this paragraph and choose the correct option from the provided answers: Multiplicative prefixes are used for other units as well, such as computer memory. The basic unit of computer memory is the byte (b). What is the unit for one million bytes?. Choices: - Megabyte - Teraybte - Bit - byte A:
byte
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Q: What is the name for a heterotroph that eats only or mainly animal foods? Read this paragraph and choose the correct option from the provided answers: Some mammals are carnivores. Carnivores are heterotrophs that eat only or mainly animal foods. Depending on their species, carnivorous mammals may eat other mammals, birds, reptiles, amphibians, fish, mollusks, worms, and/or insects. Mammals that are carnivores include anteaters, whales, hyenas, wolves, and seals. The bat in Figure below is also a carnivorous mammal. It eats insects. Carnivores that eat mainly insects are classified as insectivores. Choices: - macrophage - omnivore - herbivore - carnivore A:
carnivore
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Q: Time, mass, length, and temperature are considered to be what kinds of units? Read this paragraph and choose the correct option from the provided answers: Base units have independent scales and cannot be described by a combination of any other base units. Examples of base units used in chemistry are length, mass, temperature, and time. Choices: - support - measurement - unitary - base A:
base
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