Yo can someone answer these please its for class work thanks JUST NUMBER 4 I will mark brainliest

The body is protected against harmful flu viruses by

Hey me with this one❤❤❤❤ every organism needs food. does a cell also need it? explain very briefly.

Pl as time goes by and water goes through the water cycle again and again, the amount of water on earth: increases decreases ostays the same goes up and down