Which of the following accurately describes the way in which a muscle moves? a. when actin filaments are pulled toward the center of the sarcomere, the fiber shortens. b. during contraction, cross-bridges pull the myosin to the center of the sarcomere. c. interaction and attachment between myosin and actin cause a muscle fiber to relax. d. no atp is needed is the contraction of a muscle.

Which of the following best describes the purpose of the parathyroid hormone? a. it decreases the blood calcium level and decreases blood phosphorus level. b. it decreases the blood calcium level and increases the blood phosphorus level. c. it increases the blood calcium level and increases blood phosphorus level. d. it increases the blood calcium level and decreases blood phosphorus level.

Question 17 (1 point) where does penicillin come from? a. it is a chemical that man invented b. it is a fungus c. it is a toxin made by other bacteria d. it was discovered in archaebacteria

The primary organisms involved in the process bacteria and fungi.