Which of the following is an example of positive feedback in the lumen of the stomach?
- chief cells secrete pepsinogen, which is a precursor to pepsin.
- pepsin digests molecules of pepsinogen, producing more pepsin.
- pepsin works best in the acidic environment produced by hydrochloric acid.
- hydrochloric acid converts pepsinogen to pepsin.

Which of the following best reflects what we know about how the flu virus moves between species? a) the flu virus in a pig is mutated and replicated in alternate arrangements so that humans who eat the pig products can be infected.b) a flu virus from a human epidemic or pandemic infects birds; the birds replicate the virus differently and then pass it back to humans.c) an influenza virus gains new sequences of dna from another virus, such as a herpesvirus; this enables it to be transmitted to a human host.d) an animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates, the virus is passed to a new species such as a bird, and the virus mutates again and can now be transmitted to humans.

Which of the following is not true about a good stretching routine? a). can be hurried up once have it memorized b). improves issue elasticity and flexibility c). should last a minimum of five minutes d). prevents injury and increase athletic performance

Write an essay describing and predicting the effects of fitness-related stress management techniques on the body. should be at least 3 paragraphs