it wont et e answer i will edit it in the commetns
Answer:
A protein's primary structure is defined solely by its amino acid sequence, and is constructred by peptide bonds between adjacent amino acid residues. Secondary structure results from hydrogen bonding along the polypeptide backbone, resulting in alpha-helices and beta-pleated sheets.
The answer is D. An irritant that because embedded in the mantle
It enters and or leaves it through two separate mechanisms. One is the Sodium potassium pump which works as a gatekeeper for sodium and potassium ions that go in and out of the cell. This is active transport. Another way how it enters/leaves cells is with the help of passive ion channels where they can cross without much difficulty.
