[Solved] Which of the following is not recycled but is lost from ecosystems? A) nitrogen B) energy C) magnesium D) carbon Proctoscope: A medical instrument designed for the visual examination of the rectum. Valsalva Maneuver: A technique where one attempts to exhale forcefully with a closed mouth and pinched nose, used in medical examinations. Occult Blood: Blood present in such small quantities that it is not visible to the naked eye, often detected through specific tests. External Sphincter: A circular muscle that helps to control the passage of substances out of a body cavity or organ, such as the anus or urethra.