Which of the following is (are) essential element(s)

in ecosystems?
a. oxygen
b. hydrogen
c. carbon
d. nitrogen
e. all of these


Answer: e

Biology & Microbiology

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The structure indicated by the letter "C" above

represents a. actin. b. myofibril. c. myosin. d. myofilament. e. muscle fiber

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Phagocytic cells that digest a pathogen, then insert a bit of pathogenic antigen on their cell membrane, are described as being _____ cells.

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