Agroup of similar cells that perform a single function is called a(an)
a. nerve.
c. tissue.
b. organ.
d. organ system.

relationships play a major role in a human's emotional and mental wellbeing. healthy relationships with the people around you are even linked to a smaller production of cortisol, a stress hormone.

examples of nucleic acids are deoxyribonucleic acid (dna) and ribonucleic acid (rna).