It depends on which virus you are referring to specifically. Viruses come in many shapes and types; their variations are tremendous.
For HIV and Influenza, viruses acquire their envelops after maturation, during the budding off or detachment stage from the host cell.
Hope this helps! :)
Answer:
planetesimal is (astronomy) any of many small, solid astronomical objects, that orbit a star and form protoplanets through mutual gravitational attraction while planet is (astronomy) a body which orbits the sun directly and is massive enough to be in hydrostatic equilibrium (effectively meaning a spheroid)
Matthias Jakob Schleiden is the German biologist that said all plants were made of cells
B. To study the physical world.
This seems like a more reasonable answer then the other ones.
