How many independent variables can. e tested in a standard scientific experiment

Which of the following keep high oxygen and low oxygen blood from mixing in the frog's ventricle? A. The spongy irregular surface inside the heart B. The coordinated contractions of the atria C.

How does the movement of the diaphragm cause the air to go in and out of lungs

What is the main difference between vascular and nonvascular plants?

Why do animals have adaptations? A. There is competition for the same food sources. B. Ecosystems can change. C. Special body parts and behaviors are needed for survival. D. all of the above

How does ichabod crane's "capacious" appetite make him an easy target for brom bones' tricks?

All cells within an organism will have the same number of chromosomes except the gamete. a. True b. False

What are the steps of the food chain that includes insect-eating birds.

Which items exist on earth because of green plants?

In a word, explain the theory of evolution.

Are poisonous substances produced by bacteria