If you observe the activity at the cell membrane as the action potential passes, first you will see ________ the cell, then you will see ________ the cell
a. NA+ enter; K+ leave
b. NA+ leave; K+ enter
c. NA+ leave; NA+ enter
d. K+ enter; NA+ leave
e. K+ leave; NA+ enter
A; A local drop in the membrane potential triggers the gates of the sodium channels to open, initiating the action potential. This allows entry of sodium ions into the cell. Potassium then leaves through the potassium channel.
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Which of the following polymers contain nitrogen?
A) starch B) glycogen C) cellulose D) chitin E) glucose
In eukaryotes, acetyl-CoA synthesis takes place in the:
A. cytoplasm. B. outer mitochondrial membrane. C. inner mitochondrial membrane. D. intermembrane space of mitochondria. E. mitochondrial matrix.
Predict the expected consequence(s) of applying a toxin that blocks voltage-gated Ca2+ channels in a neuron.
A. No resting membrane potential would be observed (i.e., measures at 0 mV). B. Neuron conducts action potentials normally, but would not transmit these potentials across chemical synapses. C. The neuron would become hyperpolarized. D. A rapid increase in membrane potential at threshold voltage would not occur. E. Membrane potential would increase rapidly to peak with an action potential, but would not decrease immediately afterward.
The donor cell makes ________ whose function is to bring F- cells close enough to transfer a ________ to the recipient.
A. an F factor; replicated F factor B. a sex pilus; single strand of DNA C. a sex pilus; bacterial chromosome D. a sex pilus; double strand of DNA E. an F factor; fertility plasmid