Your answer is correct. Chitin provide the strength to insect exoskeletons. Cellulose is the strength for plant. Starch and glycogen are energy sources for life.
QUICK ANSWERNatural selection leads to evolution because the traits of those who are able to reproduce influence future generations genetics and gradually lead to these passed on traits becoming the normal state of being, thus causing the species in question to evolve. If a group of people have predominantly brown hair genes and have children, then by way of natural selection the dominant gene will increase with future generations, meaning that slowly in time this group of people will evolve to have mostly brown hair genes
I think It's Harmony between the two.
