What is the classification of virus

A virus ia. a microorganisms which causes different disease and only they are alive when they are in human body

Viruses are classified into 4 groups based on their shape: filamentous, isometric , enveloped, and head and tail.

Many viruses attach to  host cells to facilitate penetration of the cell membrane, allowing their replication inside the cell.

The virus core contains the small single- or double-stranded genome that encodes the proteins that the virus cannot get from a host cell.

Explanation:

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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:

the wires in the toaster turning red and the toast crisping and turning brown