Which of the following symbiotic relationships applies to a E. coli in the large intestine? A. Parasitism B. Commensalism C. Mutualism A. the dose that will kill some of the test population B. the dose that will cause an infection in 50% of the test population C. a measure of pathogenicity D. the dose that will cause an infection in all individuals of the test population E. the dose that will kill 50% of the test population
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Lethal dose 50 (LD50), number of pathogens that kill 50% of an experimental group (animal model) of hosts in a specified time, and infectious dose 50 (ID50), number of pathogens that infect 50% of an experimental group (animal model) of hosts in a specified time. To understand pathogenicity of two bacterial strains (A and B), various doses of the bacterial pathogen (Strain A or Strain B) are introduced into experimental host animals. The results were shown as the picture. Based on the results, which strain (A or B) is more toxic? Explain your answer.
Adi S.
24. As N approaches K for a certain population, which of the following is predicted by the logistic equation? A. The growth rate will not change. B. The growth rate will approach zero. C. The population will show an Allee effect. D. The population will increase exponentially. E. The carrying capacity of the environment will increase. 25. According to the competitive exclusion principle, two species cannot continue to occupy the same ________ indefinitely. A. habitat B. niche C. territory D. range E. biome 26. An example of Mullerian mimicry is: A. an insect that resembles a twig. B. a butterfly that resembles a leaf. C. a beetle that resembles a scorpion. D. a moth with spots that look like large eyes. E. two poisonous frogs that resemble one another in coloration. 27. An example of an aposematic coloration is the: A. stripes of a skunk. B. eye color in humans. C. green color of a plant. D. colors of an insect-pollinated flower. E. mottled coloring of peppered moths living in the unpolluted regions of England. 28. Evidence shows that some grasses benefit from being grazed. Which of the following terms would best describe this plant-herbivore interaction? A. Mutualism B. Commensalism C. Parasitism D. Competition E. Predation 29. Which of the following is LEAST likely to kill the organism it feeds on? A. Parasitoid B. Predator C. Seed eater D. Carnivore E. Parasite
Suman K.
When two bacterial strains are orally ingested by mice, Bacterium A has an ID50 = 10,000, whereas Bacterium B has an ID50 = 10, where infection is indicated by recovery of significant numbers of bacteria from feces. However, when the two bacterial strains are intraperitoneally (IP) injected into mice, Bacterium A has an LD50 = 10, whereas Bacterium B has an LD50 = 10,000, based on moribundity. a. Please draw the ID50 and LD50 curves for each bacterium. Clearly label all axes. b. Which bacterium is more virulent in the oral model of infection? c. Which bacterium is more virulent in the IP model of infection? d. Provide an explanation for the differences in ID50 and LD50 for the two bacteria in the two infection models (i.e., please explain how these results are possible).
Supreeta N.
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