本题目来源于试卷: Form and Function B.3 Membranes & Membrane Transport，类别为 IB生物学
[单选题]
How is the action of sodium-de j*vaznls kwf242zp;7pendent glucose transporters in(td morj* -)h5elbiz af*. p q4npg0r8 the small intestine, an example of indirect active trrf .az8hetnlogqrp( 5*i- b0) dmj*p4ansport?
A. Facilitated diffusion of sodium provides energy for the active transport of glucose into the cells of the small intestine.
B. Energy for the active transport of glucose into the cells of the small intestine is provided by maintenance of the sodium gradient by the $Na^+$/ $K^+$ pump.
C. Active transport of sodium via the $Na^+$/ $K^+$ pump creates a sodium gradient allowing sodium to carry glucose into the cells of the small intestine.
D. Glucose is pumped into, and sodium is pumped out of the cells of the small intestine using the sodium-dependent glucose transporter.
参考答案: B
本题详细解析:
Sodium-dependent glucose transporters are membrane proteins found in the cells of the small intestine. The sodium-potassium pump actively transports sodium ions out of the cell and potassium ions into the cell. The sodium ions move back into the cell, down their concentration gradient through the sodium-dependent glucose transporter proteins, carrying glucose molecules with them. This is an example of indirect active transport, so Choice B is correct. Choice A is incorrect as facilitated diffusion does not provide energy; it allows molecules to move down their concentration gradient without energy input. Choice C is incorrect because sodium itself does not carry glucose across the plasma membrane of cells, the sodium-dependent glucose transporter does. Choice D is incorrect as the sodium-dependent glucose transporter does not pump glucose into the cell; it co-transports glucose along with sodium ions.
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