Polypeptides are synthesized from amino acid building blocks. the condensation reactionbetween the growing polypeptide chain and the next amino acid to be added involves the loss of (a)a water molecule.(b)an amino group.(c)a carbon atom.(d)a carboxylic acid group.4-4the variations in the physical characteristics between different proteins are influenced by the overall amino acid compositions, but even more important is the unique amino acid )number.(b)sequence.(c)bond.(d)orie ntation. page 1 of 29

the abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. the region occupied by the abdomen is termed the abdominal cavity. the stomach secretes acid and enzymes that digest food. ridges of muscle tissue called rugae line the stomach. the stomach muscles contract periodically, churning food to enhance digestion. the pyloric sphincter is a muscular valve that opens to allow food to pass from the stomach to the small intestine.