The operation of the sodium-potassium pump moves . A) sodium and potassium ions into the cell B) sodium and potassium ions out of the cell C) sodium ions into the cell and potassium ions out of the cell D) sodium ions out of the cell and potassium ions into the cell

operation of SODIUM-POTASSIUM PUMP moves sodium ions out of the cell and potassium ions into the cell. The correct option is D.

When a cell membrane moves molecules or ions against a concentration gradient or against an electrical or pressure gradient, the process is called ACTIVE TRANSPORT. Different substances that are actively transported include:

--> sodium ions,

--> potassium ions,

--> calcium ions and

--> some amino acids.

There are two types of active transport which are divided according to the energy that is used to cause the transport. They include:

--> primary and

--> secondary active transport.

PRIMARY ACTIVE TRANSPORT

A typical example is the SODIUM-POTASSIUM PUMP( Na+ - k+). This is a transport process that pumps sodium ions outward through the cell membrane of all cells and at the same time pumps potassium ions from the outside to the inside. This pump helps to:

--> maintain the sodium and potassium concentration differences across the cell membrane

--> establish a negative electrical voltage inside the cells.

The mechanism or OPERATION of the pump involves the following steps:

--> two potassium ions bind on the outside of the carrier protein and three sodium ions bind on the inside,

--> ATpase of the carrier protein cleaves one molecule of ATP, splitting it to Adenosine diphosphate (ADP) and liberating a high-energy phosphate bond of energy.

--> this liberated energy then causes a chemical and conformational change in the carrier protein,

-->this leads to the extruding of three sodium ions (3Na+) to the outside and two potassium ions (2K+) to the inside.

Therefore in the operation of SODIUM-POTASSIUM PUMP moves sodium ions out of the cell and potassium ions into the cell. The correct option is D.

You can lead more about this topic here:

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!