Ascientist puts nucleotide chains of in a test tube under conditions allowing protein synthesis. soon the test tube is full of polypeptide chains composed only one the amino acid phenylalanine. what does this experiment indicate?

That UUU is triplet codon for the  amino acid phenylalanine

Explanation:

The genetic code is the set of rules used by cells to translate information from the genetic material into proteins.  This occurs during the process of translation in which the ribosome  links amino acids in an order specified by  mRNA, using  tRNA as a mediator. Three nucleotides in the mRNA that are read at a time are called codons. One codon specify one amino acid, but one amino acid can correspond to more then one codon.

the correct option is option d

the menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.