Are chemical messengers that can travel through the bloodstream and tell cells in the body what to do. They are very important in maintaining homeostasis.

Which of these is true about food webs?

A glacier recedes and exposes bare rock. Which of the following will most likely occur next? A. The bare rock will quickly break down into soil. B. Small animals will move into the area. C. Lichen will colonize the bare rock. D.

What 3 elements make up most of the mass of living organisms?

Ecologists mainly study green plants yes or no?

What would most likely happen to a native predator species if a nonnative predator species were introduced to an area? O A. The native species would outcompete the nonnative species. O B.

Change in the genetic characteristics of a population from one generation to another is called

The process by which natural forces move weathered rock and soil brim one place to another is called

Describe how testosterone production is associated with puberty in males.

Macromolecules that contain carbon, hydrogen and oxygen in a 1:2:1 ratio is called?

How might a dramatic decrease in vegeta-tion lead to a decrease in a prey species? (Hint: Think of how the vegetation, prey, and predator could be connected in a food chain.)