Explain the two reasons why scientist think the idea of species is real

What drives an advertising campaign?

Natural selection changes allele frequencies because some survive and reproduce more successfully than others.

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.