The answer is a Gland.
It is a cell or organ that secretes substances for use elsewhere in the body, or for elimination as waste. Secretion being a product of gland if it's useful to the body and an excretion being a product of the gland if it's a waste product. Glands may be exocrine or endocrine; endocrine glands lose contact with surface; have no ducts; secretes products directly into the blood due to having a high density of blood capillaries while exocrine glands secretes to the body surface or lumen; and maintain contact with surface via a duct.
Catalysts increases the rate of a reaction by lowering the need for a larger reaction. Basically, the more reactions that are created, the faster the rate of the reactions will become. An example of this is Amylase in our saliva.
Because the bacteria is constantly evolving and getting more resistant to antibiotics
It depends on where your going and how many people are going to the trip. But in my opinion I think about 3 times because you need to make stops when you need to use the restroom and when your hungry.
Sorry if I am not right :(
I hope I helped you have a great day :)