If you put the following events in the order they occur in the human digestive system, the third event in the series would be a. Cells in gastric pits secrete protons. b. Pepsin activates pepsinogen. c. HCl activates pepsinogen. d. Partially digested food enters the small intestine.

Video transcript

Hi everyone. Let's look at our next question. It says arrange the four steps in human digestion that are listed below in the correct order, then identify the second event out of the choices listed. So we have four events listed as A. B. C. And D. We need to arrange them in order and then our answer will be the one that is the second event once they're arranged in the correct order. So events are a production of hcl be entry of pollen peptides into the small intestine C proteins going to polyp peptides or D. Pepsi again becoming Pepsi. So among these events the very 1st 1 is going to be choice A production of hydrochloric acid. This hydrochloric acid is produced by the parietal cells in the stomach. It's activated by Gaston that's released in the presence of food when you begin to swallow food. So that's gonna be the first step. Then the second thing that will happen is now that we have this acidic environment uh created by the production of that hydrochloric acid. The next step will be choice D. That acidic environment will cause the pepes in again to unfold itself and in auto catalytic fashion it cleaves itself to become Pepsi. So that's gonna be our second step. So again, if we were on a test and we want to move through quickly. We've already found step number two which is Choice D. Pepsi becoming Pepsi. And we can move on. But to be thorough we'll go through other answer choices and make sure they're in order. Step three. Now that we have pepsi has cleaved itself to become Pepsi. The Pepsi and then breaks down proteins into smaller polyp peptides. That's Choice C. So the peps in breaks down proteins and now that our proteins have been broken into these smaller polyps peptides. Then we have step four, which is Choice B. Here, the polyp peptides enter the small intestines where then they'll be broken down into their component amino acids. So there we go. We've got all our events in the correct order. First, production of hydrochloric acid. Second, uh the acidic environment causes Pepsi to unfold and auto catalyze its own cleavage into the smaller protein Pepsi. In step three Peps and breaks down proteins into smaller polyp peptides. And finally step four. Those polyp peptides enter the small intestine where they're broken down into their amino acids. So our answer is step two is Choice D. Pepsi again, going to Pepsi. See you in the next video