Why are the lungs made up of these progressively smaller tubes and then

millions of tiny alveoli rather than each

lung just being a large empty sack?

because in a giant air sack, there would be no way for the capillaries to exchange gasses, and we would suffocate

Explanation:

the alveoli can only exchange one molecule at a time, they go from our lungs to our bloodstream and not mixing them up.

it's the cell cycle, but cytokines is when the cell divides.

theres 3 stages interphase,mitosis,and cytokines.

interphase prepares the cell for division.

mitosis is the process of dividing the cell,it has 4 parts interphase,anaphase,metaphase,and telophase.

lastly there's cytokines,that's when the cell divides into 2 daughter cells