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Multiple Choice
What is a major difference between facilitated diffusion and active transport?
A
Facilitated diffusion involves the movement of water molecules, while active transport involves ions.
B
Facilitated diffusion does not require energy input, while active transport requires energy.
C
Facilitated diffusion moves substances against their concentration gradient, while active transport moves them down their concentration gradient.
D
Facilitated diffusion requires energy input, while active transport does not.
Verified step by step guidance
1
Begin by understanding the basic definitions: Facilitated diffusion is a type of passive transport that allows substances to move across cell membranes through protein channels without the use of energy. Active transport, on the other hand, is a process that moves substances across cell membranes against their concentration gradient, requiring energy input, usually in the form of ATP.
Identify the key difference in energy usage: Facilitated diffusion does not require energy because it moves substances down their concentration gradient, from an area of higher concentration to an area of lower concentration. Active transport requires energy because it moves substances against their concentration gradient, from an area of lower concentration to an area of higher concentration.
Consider the direction of movement: In facilitated diffusion, substances move down their concentration gradient, which is a natural process that does not require energy. In active transport, substances are moved against their concentration gradient, which is not a natural process and thus requires energy.
Examine the role of transport proteins: Both facilitated diffusion and active transport involve transport proteins. In facilitated diffusion, these proteins help substances move across the membrane without energy. In active transport, transport proteins, often called pumps, use energy to move substances against their gradient.
Clarify misconceptions: Facilitated diffusion does not involve the movement of water molecules specifically; it can involve various substances. Also, facilitated diffusion does not move substances against their concentration gradient, and it does not require energy input, unlike active transport.