Mechanisms that move substances across membranes against concentration gradients are

a. calcium ions in the calcium pump.
b. membrane pumps.
c. ATP molecules.
d. passive transport.
e. facilitated diffusion.


B

Biology & Microbiology

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At least some of the cells of a mammalian heart in the final phase of development would most likely be

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During which step of urine formation will water, glucose and amino acids be returned to the blood? a. Urination b. None of these choices

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The cells of a gametophyte are

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