Answer:
phosphorus
Explanation:
Since Phosphorus is an essential component of phospholipids, nucleic acids, phosphoproteins (casein), high energy phosphate esters (ATP), hexose phosphates, creatine phosphate, it also provides strength to the exoskeletons of clams and oysters.
Answer:
cardiovascular
Explanation:
Since there is no option of endocrine system, I would say cardiovascular because it involves the bloodstream
Answer:
Populations have variation in traits due to random mutation, crossing over and environmental conditions.