Answer:
Endocardium
Explanation:
The endocardium makes the innermost lining of the wall of the heart. It is present over the thin layer of connective tissue. The function of the endocardium is to provide a smooth lining for the chambers of the heart. The valves present in the heart also have endocardium. The dense connective tissue of the heart valves is covered by endocardium.
The presence of the smooth endocardium made up of endothelium reduces the surface friction as blood passes through the heart. The endocardium of heart chambers is continuous with the endothelial lining of the large blood vessels that are attached to the heart.
B. Chitin- its a hard and tough substance that occurs widely in nature, particularly in the shells (exoskeletons) of arthropods such as crabs.
Protein synthesis is the process in which cells make proteins. It occurs in two stages: transcription and translation. Transcription is the transfer of genetic instructions in DNA to mRNA in the nucleus. It includes three steps: initiation, elongation, and termination.
