reproduction, heredity, variation in fitness or organisms, variation in individual characters among members of the population.
A diet deficient in calcium can cause osteopenia. The deficiency of calcium may Cause a low bone density which is a condition caused in osteoporosis. Hence the correct answer is B osteopenia.
Answer:there is a cell division as it occurs every 20min
Answer: D) Pulmonary and aortic valves.
Explanation
There are two main heartbeats from a healthy heart.
The first beat is called the S1 or the lub, and it occurs when the atrioventricular valves (comprising the mitral and tricuspid valves) close.
The second beat is called the S2 or the dub, and it occurs when the semilunar valves (comprising the aortic and pulmonary valves) close.
Listening for heart beats is an essential part of cardiac auscultation.