Question

Consider the transport of bicarbonate into a red blood cell as depicted below with the concentration of bicarbonate greater outside the cell than inside. Which of the following is true regarding the movement of bicarbonate into the cell? For this question, the bicarbonate concentration gradient = [HCO3 Joutside 7 [HCO3linside HCO3 movement of bicarbonate into the cell is always spontaneous O movement of bicarbonate into the cell is always non-spontaneous movement of bicarbonate into the cell is spontaneous only if the bicarbonate concentration gradient is very large movement of bicarbonate into the cell is spontaneous only if the bicarbonate concentration gradient is very sme

Answer 1

movement of bicarbonate into the cell is spontaneous only if the bicarbonate concentration gradient is very large.

Given that the bicarbonate concentration gradient = [HCO₃]_outside / [HCO₃]_inside

In the bicarbonate concentration gradient, the numerator is outside bicarbonate concentration and denominator is inside bicarbonate concentration.

Thus a large bicarbonate concentration gradient indicates a large numerator value, thus large outside bicarbonate concentration.

When then is large concentration of bicarbonate outside than inside the cells, there is very large concentration gradient develops and movement of bicarbonate ions become spontaneous.

When there is very small concentration gradient, bicarbonate ions start moving outside the cell from inside as the outside concentration is much higher.

spontaneity of movement of bicarbonate ions depends on concentration of ions inside and outside of the cell and are not always constant.