Which statement best describes the human respiratory system? A) It is composed of a network of moist passageways that permit air to flow from the external environment to the lungs. B) Each cell of the human body is in direct contact with the external environment, and gas exchange occurs by diffusion. C) The external body surface is kept moist to allow for gas exchange. D) Gases diffuse across membranes on both the external and internal surfaces of the body.

What is true of all organisms in the kingdoms protista, plantae, fungi, and animalia? a. they are multi-celled. b. they are photosynthetic. c. they have cells that contain membrane-bound organelles. d. they contain cells that lack membrane-bound organelles.

In the united states there are strict fishing seasons and limits, but not all countries enforce similar laws. in bangladesh there are few if any fishing restrictions. what might be the reason for less restrictions in smaller countries like bangladesh? a) the united states is the only country worried about overfishing. b) the united states wants to limit the supply of fish to increase the price. c) bangladesh and smaller countries have an unlimited supply of fish in their coastal waters. d) small countries, such as bangladesh, are practicing subsistence fishing, taking only the fish needed to survive.

If you relate the doppler effect on sound to the color of light waves, a police car would be the color as it approaches and the color as it recedes away from the observer.