Viruses can “reproduce..."

A) independently of host cells

B) independently of host cells given they take up the organelles first

C) only within host cells

D) only with the assistance of
other viruses

B.

Explanation:

They take up the host organelles to reproduce more viruses inside.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.