Humans often think of themselves as unique, but in reality there are only a few distinguishing features. which of these is unique to humans as compared to other mammals?
a. eccrine glands for thermoregulation
b. red blood cells that lack nuclei
c. messner's corpuscles for sensing pressure
d. a fully erect posture associated with bipedalism

b. Red blood cells that lack nuclei

d. A fully erect posture associated with bipedalism

Explanation:

Eccrine glands can be found on horses, you may have seen horses sweeting. The pressure sensors can be found in other apes too. Fully erect posture is a characteristic of humans, other apes or monkeys may walk sometime like this, but their main locomotion is in 4 extremities. Non nucleated is a characteristic that gives an advantage because more oxygen can be carried  inside red blood cells making respiration more efficient.

the answer is c) an oak tree

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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