Interacting systems of molecules enclosed in compartments called __________ evolved 3.8 billion years ago in living organisms.

A. cells
B. organs
C. microspheres
D. tissues


Answer: A. cells

Biology & Microbiology

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Humans are unable to get metabolic energy from cellulose because:

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This type of cell is closely associated with a companion cell

a. sieve tube member b. tracheid c. vessel elements d. sclerenchyma e. collenchyma

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What is the most important role of bacteria in the environment?

A) as disease-causing agents B) as fungal control C) as decomposers D) as a source of restriction enzymes

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Which of the following is NOT characteristic of RNA?

A) It is a helical polymer. B) It is usually double-stranded. C) Its "backbone" is composed of pentoses and phosphates. D) It contains both purines and pyrimidines. E) It can function as a catalyst.

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