Can you please help me answer this question Please clearly s

Can you please help me answer this question.

Please clearly state the answer.

Question 6

Facilitated diffusion across a biological membrane requires ________ and moves a substance ________ its concentration gradient.

energy and transport proteins . . . down

energy . . . down

transport proteins . . . down

energy and transport proteins . . . against

transport proteins . . . against

Solution

Answer : The correct answer is C (Transport proteins and down) : Facilitated diffusion across a biological membrane requires TRANSPORT PROTEINS and moves a substance DOWN its concentration gradient.

Explanation : Facilitated diffusion is a type of passive transport, in which ions or molecules cross the membrane repidly because specific permeases in the membrane facilitate their crossing. It does not requires metabolic energy and occurs only in the direction of concentration gradient. This in contrast to active transport which required metabolic energy and occurs against the concentration gradient.

Examples of facilitated diffusion : Ionic transport through charged pores, calcium ion channels, Glucose transport in erythrocytes etc.,