Aresearcher is culturing mouse cells in the laboratory. when he treats cells with four vitamins―w, x, y, and z―these cells survive and grow; he knows that some of these vitamins are essential nutrients. however, when he treats cells by removing one vitamin at a time, he gets the following results: vitamin w, cells live; vitamin x, cells live; vitamin y, cells die; vitamin z, cells die. based on these results, which of the vitamins are likely essential nutrients?

During the first month of development, how many layers of cells make up the embryo? a. 1 b. 2 c. 3 d. 4

During the past few weeks or months, have you noticed any exercises that have become too easy for you? do you think you need to increase the intensity in any of the three exercise areas in your workouts? evaluate your exercise progress in the three exercise areas (cardiovascular, resistance, and flexibility) and list what modifications, if any, you may need to make in your exercise routine.

Poliovirus is an rna virus of the picornavirus group, which uses its rna as mrna. at its 5' end, the rna genome has a viral protein (vpg) instead of a cap. this is followed by anontranslated leader sequence, and then a single long protein-coding region (~7000 nucleotides), followed by a poly-a tail. observations were made that used radioactive amino acid analogues. short period use of the radioactive amino acids result in labeling of only very long proteins, while longer periods of labeling result in several different short polypeptides. what conclusion is most consistent with the results of the radioactive labeling experiment? a) host cell ribosomes only translate the viral code into short polypeptides.b) the rna is only translated into a single long polypeptide, which is then cleaved into shorter ones.c) the rna is translated into short polypeptides, which are subsequently assembled into large ones.d) the large radioactive polypeptides are coded by the host, whereas the short ones are coded for by the virus.