What is the function of the structure labeled A in the diagram below? A. To protect the delicate tissue of the lungs

B. To exchange gases between the lungs and blood vessels

C. To contract, thus causing the chest cavity to enlarge

D. To chemically digest food exiting the esophagus

True or false: (a) the strings of little red dots represent carbohydrates. (b) the model is called a bilayer because there are two main types of molecules present, lipids and proteins. (c) the many black lines represent amino acid tails. (d) this model shows membrane transport. (e) the blue ovals are hydrophobic. (f) the blue ovals represent phospholipid heads.