Echinoderms generally have endoskeletons.
a. true
b. false

True.

Explanation:

Echinoderms are invertebrates that lacks the notochords and other well defined structures present in vertebrates. Echinoderms are generally marine, aquatic animals.

The skeleton of echinoderms are endoskeleton. They endoskeleton is made up of calcium carbonates interlocking in the form of plates and spines. The skeleton of echinoderm are covered by epidermis.

Thus, the answer is true.

the relative standard reduction potential of the half-cell in which reduction occurs; more positive than the other half-cell. reduction is a chemical process in which electrons are added to an atom or an ion; it always occurs accompanied by oxidation of the reducing agent.