The human stomach is lined with glands that produce several chemicals that in the process of digestion. one of these chemicals is hydrochloric acid, a powerful acid that makes the stomach very low in ph. another substance is mucus--this substance lubricates and protects the stomach wall. a third substance is the enzyme pepsin which to break down protein molecules into smaller molecules called peptides. if the chemical enzyme pepsin was mixed with some proteins in a test tube in a laboratory, which of these outcomes would you predict? a) pepsin would probably not break down proteins in the test tube because enzymes cannot exist outside of the human body. b) pepsin would partially break down the protein molecules but would not work well due to the absence of dna in the test tube. c) pepsin would probably not break down proteins in the test tube because pepsin is designed to work at very acidic ph ranges. d) pepsin would break down the protein molecules equally well in the laboratory as in the human stomach since it is a stable chemical.

C) Pepsin would probably NOT break down proteins in the test tube because pepsin is designed to work at very acidic pH ranges.

Explanation:

Pepsin is the main proteolytic enzyme active in gastric juice, an aqueous solution rich in hydrochloric acid and enzymes that act on protein digestion. Gastric juice leaves the stomach with very low pH levels, which means that the stomach becomes extremely acidic, an ideal environment for the work of enzymes that work on digestion, including pepsin. Pepsin is produced by the main stomach cells via zymogens and has the function of digesting proteins by catalyzing the hydrolysis of these molecules by breaking down the peptide bonds between some amino acids. The products of this breakdown are relatively long chains of amino acids, oligopeptides such as peptides and proteoses.

As stated earlier, pepsin works at very low pH conditions, ie in very acidic environment, so we can conclude that if pepsin were mixed with some proteins in a test tube, pepsin would probably not break down the proteins. in the test tube because pepsin is designed to work in very acidic pH ranges.

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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hey bro i looked it up on google the structure of the eye-spot in euglena viridie, e. ehrenbergii, and phacus pyriyorme is not as franzé haa described it. the so-called “crystal body” and “lens bodies” were not found in any of the individuals of the species examined by me. as earlier observers have stated, the eye-spot consists simply of a mass of pigment granules arranged in a single layer, and probably embedded in a protoplasmic framework, but the latter could not be seen, and its presence was only inferred from the fact that the pigment granules must be held together in some way, thd the eye-spot as a whole is capable of expansion, and that the pigment granules can be separated from each other.

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