The cell-free in vitro translation system utilized by Nirenberg and Matthaei to determine the first "words" in the genetic code utilized addition of into purified E. coli extracts:

Radio active amino acids

Explanation:

The Nirenberg and Matthaei performed the experiment which showed the relationship between the nitrogenous bases present on the mRNA and the amino acids.

They knew that the amino acids are coded by the bases on the mRNA and they cultured the E.coli bacteria, ruptured them and released the cytoplasmic content from them.

Then they added the artificially synthesized RNA molecule attached with radioactive molecules and added them to different tubes. From this, they concluded that there is 64 combination of triplets which are responsible for the production of a variety of amino acids.

Thus, Radioactive amino acids are the correct answer.

one is through turgidity. this occurs before ground tissue ( collenchyma

and sclerenchyma cells) become well

developed to give structural support to the plant as it grows bigger. the xylem

tissue (composed of rigid tissue) of the young

plant render this support and also maintaining osmotic turgidity of the surrounding

plant cells.