Hello there :)
What I could say though are the following of the function of proteins:
Building Tissues and Muscles. Protein is necessary in building and repairing body tissues. ...
Hormone Production. ...
Enzymes. ...
Immune Function. ...
Energy.
If the inner lining of the air sacs neither thin nor highly vascularized, then it can be inferred that AIR SACS ARE CANNOT BE THE SITES OF GASEOUS EXCHANGE BETWEEN AIR AND BLOOD. Air sacs are generally lined with mucus and surrounded with blood capillaries.
In case of birds, air sacs play an important role in respiratory system.
The true answer of your question is :
OH : HYDROXYL GROUP
NH2 : AMINO GROUP
CH3 : METHYL GROUP ( but in rather broader terms, that functional group of formula CnH2n+1 where n is an integer is called ALKYL GROUP where by substituting n by 1,2,3... we obtain methyl for n = 1, ethyl for n = 2, and propyl for n = 3 )
COOH : CARBOXYL GROUP is the correct answer since carbonyl is characterized by the presence of functional group C=O in general the formula of the compound would be
R-C=O-R’ where R and R’ are alkyl groups like methyl for example. However the carboxyl group could be thought of as a summation of carbonyl + hydroxyl ( CO + OH ) resulting thus in COOH.
I hope you’ll understand everything, anyway if not i’m always here to help. ♥️
How old is Darren? we need to know his age before we answer