A scientist suspects that the food in an ecosystem may have been contaminated with radioactive nitrogen over a period of months. Which of the following substances could be examined for radioactivity to test the hypothesis?
A) the cell walls of plants growing in the ecosystem
B) the hair produced by humans living in the ecosystem
C) the sugars produced during photosynthesis by plants growing in the ecosystem
D) the cholesterol in the cell membranes of organisms living in the ecosystem
Answer: B
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The process in which NH4
+ is oxidized to NO3 ? is called
a. nitrification. b. ammonification. c. nitrogen cycling. d. nitrogen fixation. e. nitrogen assimilation.
Which organ of the gastrointestinal tract has a large commensal population of microorganisms?
A. Large intestine B. Small intestine C. Pancreas D. Liver E. Salivary glands
What activity is likely to cause the intermediate filaments that make up the nuclear lamina to reassemble after mitosis has ended?
a) acetylation b) methylation c) phosphorylation d) dephosphorylation
Glucose is made during which of the following reactions?
A) The light reactions only B) The Calvin cycle only C) Both the light reactions and the Calvin cycle D) Neither the light reactions nor the Calvin cycle