Consider one such cell where the magnitude of the potential difference is 40 mV, and the inner surface of the membrane is at a higher potential than the outer surface. A sodium ion (Na ) is initially just outside the cell membrane (initially at rest). How much work (in J) is required for a cell to absorb the ion, so that it moves from the exterior of the cell to the interior

W = 6.4x10⁻²¹J

Explanation: Work is the energy transferred to or from an object due to the application of a force along a displacement.

The ion Na is gaining energy to move from a lower potential to a higher one.

For this to happen, the work done is calculated as

in which

W is work in Joules (J)

q is charge in Coulomb (C)

is potential difference in Volts (V)

The ion Na has one positive charge. In coulombs, the charge is

q = 1.6x10⁻¹⁹C

The potential difference in Volts is

= 40x10⁻³ or 4x10⁻²V

Calculating

W = 1.6x10⁻¹⁹. 4x10⁻²

W = 6.4 x 10⁻²¹ J

The work done to move an ion of sodium from the exterior to the interior is 6.4 x 10⁻²¹ J.

they each offer a fresh glut of resources to the organisms that can arrive and exploit them. as individuals and new species continue to appear, they actively and passively alter the environment. competition for shared resources increases, local abiotic and biotic conditions shift, and the relative abundances of species change accordingly. the process is called ecological succession, and it is one of the earliest and most well-known concepts in ecology.