Multicellular organisms must be protected from the external environment. because of this, cells of even the simplest multicellular organisms are arranged to form an external barrier of

a)
cellular tissue.

b)
epithelial tissue.

c)
connective tissue.

d)
interstitial tissue.

An adult inhales about 6.0×10−4 m3 of fresh air during a breath. only 20% of fresh air is oxygen. assume the pressure in the lungs is 1.0×105 paand the air is at a temperature of 300 k. how many oxygen molecules are in each breath? a. 1.4x10^23 b. 2.9x10^21 c. 4.9x10^-4 d. 2.9 x10^25