Echinoderms are deuterostomes. Pentaradial adult echinoderms provide a good example of a cephalized animal. Think of the skeleton of a bony fish. The skeleton of the tail of a pig is formed from a. cervical vertebrae. In fertilized Drosophila melanogaster eggs, the location of bicoid protein determines the site of the future a. thorax.
Blood is an example of a. epithelial tissue.
A receptor for a certain insect hormone is found in the nucleus of target cells. From this we infer that the hormone must be a. a water-soluble hormone. When a particular protein hormone binds to its receptors on target cells, adenylate cyclase bound to the inner surface of the plasma membrane is activated. Imagine that this hormone is applied to cells in a culture dish. The voltage-gated sodium channels of neurons are a. opened by hyperpolarization.