Which of these is a copy of dna that is used to direct the synthesis of a specific protein?
a. mrna
b. rrna
c. trna
d. ribosome?

What is the name for a substance formed in a chemical reaction

Where substance is produced during cellular respiration

Which of the following is a reason why early living organisms on earth could not have survived on the surface? 1. the lack of an ozone layer 2. the lack of oxygen in the atmosphere 3. the fact that these organisms were single-celled