Adeep sea robot is sent to the bottom of the ocean. what will it most likely observe, in terms of the numbers of photosynthetic organisms and light conditions? a.) many photosynthetic organisms in an environment with very little light b.) few photosynthetic organisms in an environment with very little light c.)many photosynthetic organisms in an environment with large amounts of light d.)few photosynthetic organisms in an environment with large amounts of light

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation: