Answer:
When calcium concentration increases during depolarization, it shifts the conformation of troponin and tropomyosin, and actin is able to associate with myosin. As calcium is taken up again by the sarcoplasmic reticulum the muscle cell relaxes.
2. solar system 1. is elliptical
Answer:
I think its D or B. Not sure but its either one
Explanation:
NUTRITION AND AGE FACTOR!