List and describe three common defense mechanisms. Description is needed.

hand-to-hand combat

a gun

heavy object (baseball bat or something like that)

Explanation:

I don't know what situation you mean, but if the person is caught off guard, the first defense mechanism is your own body, punches, kicks, stuff like that

If someone is attacking, there's a 50/50 chance that they will have a gun, in that case, the gun can be used on either side, the attacker or the attacked

If someone is attacking, it is also possible that heavy objects, baseball bats, table legs, pipes, are going to be used on either side.

Hope this helps:/

your answer is "the 1950's"

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.