While scientists have made enormous discoveries, there is always more to learn. Knowledge is built on and reviewed. Sometimes new information reveals an error in understanding from the past. The study of how the world works is always ongoing.
Answer:
plasma membrane/ cell membrane
The answer is c. oxygen.
Cellular respiration includes glycolysis, link reaction, Krebs cycle, and electron transport chain (ETC), in that order. The main function of ETC is a production of ATP. In this series of oxidation-reduction reactions, electrons from the previous stages of cellular respiration are taken and transported to the oxygen which is the final acceptor of electrons. As the result, water and ATP are produced.
The given blank can be filled with the production of endorphins.
The endorphins are the hormones, which are responsible for the activation of the opiate receptors in the body. They are the natural pain killers. The activation of the opiate receptors causes the analgesic effects on the body.
These endorphins are secreted in the brain and the nervous system. The effect of the endorphins is similar to that of the morphine.
