What causes the instant withdrawal reflex interneurons?

How can antibodies "remember" a particular bacterial invader or "antigen" on that invader?

One of the reasons that stars are so large is because

Which example describes a mutualistic relationship between organisms? young wasps prey on caterpillars. crabs eat the remains of dead fish. tapeworms feed on food in the intestines of cats ants protect a tree on which they feed.