Any substance dissolved in water is called a

Explain how paleontologists use trilobite fossils as index fossils for various geologic time periods.

Can a trait be both polygenic and have multiple alleles? explain why or why not.

Which of the following best describes the purpose of the parathyroid hormone? a. it decreases the blood calcium level and decreases blood phosphorus level. b. it decreases the blood calcium level and increases the blood phosphorus level. c. it increases the blood calcium level and increases blood phosphorus level. d. it increases the blood calcium level and decreases blood phosphorus level.