Question

question 21 of 25 when a muscle contracts, calcium ions are forced into an extracellular space against their concentration gradient. which mechanism explains how this happens? passive transport is used to move the calcium up its concentration gradient. the diffusion of calcium ions from high to low concentrations allows this to happen. an influx of atp provides the energy needed for an ion pump. atp and diffusion work to move the calcium ions up the gradient.

Explanation:

Moving ions against their concentration gradient requires energy. ATP is the energy - currency of the cell. Ion pumps use the energy from ATP hydrolysis to move ions against their concentration gradients. Passive transport and diffusion move substances along their concentration gradients, not against them.

Answer:

An influx of ATP provides the energy needed for an ion pump.