Nitrogen has five electrons in its valence shell. How many electrons does it need to gain to complete its valence shell?
a. one
b. two
c. three
d. seven
e. eight
c
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A fisherman who cut himself on a fishing hook later develops a cutaneous disease at the inoculation site. The exudate is aspirated and set up on a routine AFB medium for culture. It is incubated at 37°C, but no growth is observed after 8 weeks; however, a slide of the exudate was AFB-positive. Which one of the following statements explains these findings?
a. The infection is most likely the result of a viral infection. b. The organism should have been incubated at 30°C. c. The organism should have been incubated at 42°C. d. The infection is most likely fungal in na-ture.
Which biome is characterized by an abundance of trees that lose all of their leaves at a specific time of
year? a. taiga only b. tropical rain forest only c. temperate rain forest only d. temperate deciduous forest only e. both the temperate and tropical rain forests
In your own words, explain why some bacterial species produce endospores. What are their purpose?
What will be an ideal response?
The half-life of carbon-14 is 5,600 years. A fossil that has one-eighth the normal proportion of carbon-14 to carbon-12 is probably
A. 11,200 years old. B. 16,800 years old. C. 5,600 years old. D. 22,400 years old. E. 2,800 years old.