Why do phospholipids form a double layer?

If a young male's body is just beginning the process of producing sperm, when is it likely that he would ejaculate mature, viable sperm"

Which of the following is not true of the formation of a bacterial translation initiation complex? a. if-3 binding to gtp is required for the charged trna to associate with the first mrna codon. b. n-formylmethionyl-trnafmet binds in the p site. c. if-1, if-2, and if-3 dissociate upon the 50s subunit binding. d. the 30s ribosome associates with the mrna before the 50s ribosome.

What are the base pairing rules? how does this allow for dna replication