Animals possess nerve networks or nervous systems to respond to their environment. But
the single celled Amoeba does not possesses any nerve cell, so, how it come to know
whether a particle it encounters is a grain of sand and not its dinner?
(a) By chemotaxis
(b) By skin
(c) By hormones
(d) All of these
(a) Although the Amoeba has no sense organs, it responds to chemical stimuli. It makes this determination by chemotaxis, a kind of chemical sense. This is the same response mechanism that our white blood use when they encounter and phagocytoze a pathogen.