Which kind of action is a cause of air pollution? A. Trash is dropped in a national wildlife preserve. B. Poisons are released into a major river. C. Tuna are fished to extinction. D. Gasoline is burned by a car engine.

How are the testes and ovaries similar? a. both produce sex cells. b. both connect internal reproductive organs to the exterior. c. both transport sex cells from their site of production. d. both store mature sex cells.

The transport tubes for food coming down the plants are called?

Which of the following is not associated with invasive species?