Which protozoan has a unique appearance, with a blue halo, when viewed using ultraviolet fluorescence microscopy?
giardia lamblia
cryptosporidium hominis
cyclospora cayetanesis
entamoeba histolytica

Cyclospora cayetanesis

Explanation:

Cyclospora cayetanensis is a human protozoan parasite belonging to the phylum Apicomplexa. Cases of human cyclosporosis have been reported in the Americas, the Caribbean, Africa, England, Eastern Europe, and other regions of the world. Currently, this protozoan infection has only been found in humans. A curiosity about this protozoan is that it has a unique appearance with a blue halo when viewed using ultraviolet fluorescence microscopy.  This can be seen in the image below.

it is a

explanation:

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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