How do active transport and facilitated diffusion differ?
a
one uses help from proteins and the other does not
b
one requires energy and the other does not
c
active transport moves molecules against a concentration gradient and facilitated diffusion does not
d
both b & c
d) both b & c
The correct answer is d) both b & c.
Active transport and facilitated diffusion differ in several ways:
1. Use of proteins: Active transport utilizes carrier proteins or pumps to actively move molecules across the cell membrane, while facilitated diffusion also relies on transport proteins to facilitate the movement of molecules across the membrane.
2. Energy requirement: Active transport requires the expenditure of energy in the form of ATP (adenosine triphosphate), while facilitated diffusion does not require energy and utilizes the concentration gradient as the driving force.
3. Direction of movement: Active transport is capable of moving molecules against their concentration gradient, from an area of lower concentration to an area of higher concentration. In contrast, facilitated diffusion moves molecules along their concentration gradient, from an area of higher concentration to an area of lower concentration.
Therefore, both statements b) (one requires energy and the other does not) and c) (active transport moves molecules against a concentration gradient and facilitated diffusion does not) are correct.
The correct answer is d) both b & c, which means that both active transport and facilitated diffusion require energy and active transport moves molecules against a concentration gradient while facilitated diffusion does not.
To understand the differences between active transport and facilitated diffusion, let's break down each process:
1. Active transport:
Active transport is a process in which cells move molecules against a concentration gradient, meaning from an area of lower concentration to an area of higher concentration. This movement requires the expenditure of energy in the form of ATP (adenosine triphosphate). Active transport is necessary when the cell needs to accumulate molecules against their concentration gradient or when molecules need to be removed from the cell against their concentration gradient. It is performed by specific proteins embedded in the cell membrane called active transporters or pumps.
2. Facilitated diffusion:
Facilitated diffusion is a process that helps molecules move across a cellular membrane from an area of higher concentration to an area of lower concentration. However, unlike simple diffusion (where molecules pass through the lipid bilayer directly), facilitated diffusion involves the assistance of specific proteins called transporters or carriers. These proteins create channels or tunnels that allow specific molecules to move across the membrane in a facilitated manner. Unlike active transport, facilitated diffusion does not require energy input as it follows the direction of the concentration gradient.
So, in summary:
- Active transport requires energy and moves molecules against the concentration gradient.
- Facilitated diffusion does not require energy and moves molecules along the concentration gradient.