Well viruses inject their RNA or DNA into a cell, so assuming they also inject their RNA or DNA into a bacteria to reproduce, then they basically treat the bacteria cell like any other cell..
Answer:
they both hold data and show you a scale
Cast fossil is a raised fossil that has filled in the impression from a mold.
B. long fibres in celery
(I've done an experiment in my science class once on xylem tissue on celery)
The answer is most definitely A! bears thrive in a certain environment so if you were to cut it down, it might wipe out a major food source for the bears and kill them off!