The right answer is It connects amino acids.
• Amino acids are the building blocks of proteins.
• There are 21 amino acids, but only one type of binding used to connect them: it is the peptide bond.
The peptide bond is formed during the translation step by a covalent bond between an α-amino group of an amino acid and the carboxylic group of another amino acid. A molecule of water is eliminated.
I'm not sure how exactly you wanted this question to be answered. You're either talking about the symmetry where animals would have two legs or two arms for example and thus producing a pair of each muscle on both sides of the body, or you're refering to the development of agonistic and antaonistic muscles where each of them served a different purpose; either extending or contracting.
Answer:
Index Fossils can be used to identify a specific time period.
Explanation:
