For the first question, the answer is B. The brief refractory period prevents reopening of voltage-gated Na+ channels. During the refractory period, the sodium channels are inactive, and this prevents the action potential from traveling backward along the axon.
For the second question, the answer is C. Na+ ions moving out of the cell. This process involves the sodium-potassium pump, which uses ATP to actively transport Na+ ions out of the cell and K+ ions into the cell. This process helps maintain the resting membrane potential and requires energy from ATP hydrolysis.
I have two questions:
1. Why are action potentials usually conducted in only one direction along an axon?
A. The axon hillock has a higher membrane potential than the terminals of the axon.
B. The brief refractory period prevents reopening of voltage-gated Na+ channels.
C. Voltage-gated channels for both Na+ and K+ open in only one direction.
D. The nodes of Ranvier can conduct potentials in only one direction.
E. Ions can flow along the axon in only one direction.
2. Which of the following membrane activities require energy from ATP hydrolysis?
A. Movement of water into a cell
B. Movement of water into a paramecium
C. Na+ ions moving out of the cell
D. Movement of glucose molecules
E. Facilitated diffusion
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The first question I have no clue.
I do have an idea for the second question, though. I know it's not A or E, because diffusion and osmosis is part of passive transport, requiring no energy. I also don't think it's B, since I'm guessing that osmosis in a prokaryote works the same way. The last two I'm not quite sure about...
1 answer
1 answer