Microorganisms in the human colon are more often being described as mutualistic with human hosts rather than commensalistic. Why has this change in the definition of a symbiotic relationship occurred?
A. As we learn more about the ecology of the human microbiome, we have learned that these organisms are dependent on the nutrients that we provide for their survival.
B. As we learn more about the makeup of the human digestive tract, we realize that some microorganisms are potentially pathogenic, while others are not.
C. As we learn more about the ecology of the human microbiome, we recognize our dependence on these organisms for immunity, vitamin production, and other essential processes.
D. All of the choices are correct.
Answer: C
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It appears that eukaryotic diversity took off around 800 million years ago. Which of the following is thought to be responsible for this?
A. By 800 million years ago, enough time had passed since the arrival of eukaryotes for evolutionary adaptation to take place. B. Eukaryotic organisms first arrived 800 million years ago, so when they did, they quickly diversified. C. Chloroplasts first arrived 800 million years ago. D. Environmental conditions changed 800 million years ago, namely an increase in oxygen and a decrease in sulfide. E. All of the answer options are correct.
It is believed that eukaryotes evolved their mitochondria from a symbiotic relationship with a free-living aerobic bacteria.
Answer the following statement true (T) or false (F)
The study of the factors that influence changes in a population's size is
A. population density. B. population geology. C. population dynamics. D. population dispersion. E. population ethology.
A(n) ________ is a virus that infects bacterial cells
A) virion B) prion C) bacteriophage D) nucleocapsid E) envelope