If one organism lives on or in another and gets its energy by harming the other, their relationship can be said to be A. competitive
B. beneficial
C. positive
D. parasitic

Ecology can best be described as the study of what

Anormal strand of dna is shown below, followed by the same strand of dna after mutations have occurred.

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.