A student weighed each of several mice born from the same parents, and then placed the mice in separate cages where all mice received identical diets. Half of the mice were given additional amounts (supplements)
of selected amino acids. Half of the mice received no amino acids. After four weeks, all mice were weighed
again and their weights were compared.

the element that provides strength to the exoskeletons of clams and oysters is phosphorus. this is so because calcium carbonate is the main component in the shells.

explanation:

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.