Compare and contrast the body of a crayfish with that of an insect.

Insects have a distinct set of characteristics which all must have if they are insects. They must have three pairs of legs (even though sometimes they may appear different as larvae, such as caterpillars), a set of mouth parts, and a head, thorax, and abdomen.

b. the carbon cycle ensures living things have a source of hydrogen

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.