In some cells, there are many ion electrochemical gradients across the plasma membrane even though there are usually only one or two proton pumps present in the membrane. The gradients of the other ions are most likely accounted for by _____

A) cotransport proteins
B) ion channels
C) pores in the plasma membrane
D) passive diffusion across the plasma membrane
E) cellular metabolic reactions that create or destroy ions


Answer: A

Biology & Microbiology

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Mendel selected pea plants for his experiments because ____

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The root apical meristem is surrounded and protected by a structure called the

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In adaptive immunity, the ______ are the cells that poke holes in foreign cells.

Fill in the blank(s) with the appropriate word(s).

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Which bacterial structures are important for adherence to surfaces?

A. endospores B. cell walls C. fimbriae D. capsules E. flagella

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