Which of the following is the BEST description of structure of the cell (plasma) membrane two phospholipid layers with the "heads" facing away from each other

one phospholipid layer with the head facing towards the inside of the cell

two phospholipid layers with the "heads" facing towards each other

one phospholipid layer with the head facing towards the outside of the cell

If the coding part of an mrna molecule is 1800 nucleotides (bases) in length, this molecule will contain codons and code for a polypeptide that is amino acids long.

Humans are believed to have evolved in coastal regions in east africa. the region had an abundant supply of fish for early humanoids to eat. when scientists analyze the fads gene they see an interesting pattern. people whose families have lived in this area of east africa for generation show a high level of diversity in alleles for the fads gene. conversely, people whose families had migrated inland a moderate distance from sources of fish showed a much lower diversity for fads gene alleles. additionally, the fads alleles found in people whose family has lived inland for generation are almost all gene alleles which produce fads proteins with a high level of function and activity. how do anthropologists explain this?

One of the purposes of transcription is to produce a sequence of bases that