How. is the structure of a unicellular organism different than the structure of a multicellular organism? how does this affect function? pls i've asked this question 3 times already : /

The oxidizing agent our bodies use to obtain energy from food is oxygen (from the air). if you breathe 15 times a minute (at rest), taking in and exhaling 0.5 l of air with each breath, what volume of air do you breathe each day? air is 21% oxygen by volume. what volume of oxygen do you breathe each day?

About how many years does it take for one cycle of surface water to become deep water and then surface water again in the oceans? 101001,000

Which of the following must be true for a fossil organism to be useful as an index fossil? a. the fossil organism must be widespread geographically. b. the fossil organism must be abundant. c. the fossil organism must be limited to a short span of geologic time. d. all of the above.