The main energy source used by humans has changed over time from

A. fossil fuels to solar.

B. wood to wind.

C. wood to fossil fuels.

D. fossil fuels to nuclear.

Blood is carried away from the heart to provide oxygen to rest of the body by the

Why do two-dimensional maps of earth have distortions? A. Earth is three-dimensional, but maps are two-dimensional B. cartography is an inexact science C. cardinal directions do not apply to two-dimensional maps D.

Cell membrane consist of mainly

Opponent-process cells have been located in the thalamus and the hypothalamus. lens and the retina. retina and the thalamus. cornea and the lens.

Which statement best describes the current scientific view of birds? A) a group of feathered, ectothermic lizards that lack teeth B) a group of flying mammals that are derived from monotremes, which also lay amniotic eggs C) a group of flying,

What is not part of cell theory

Muscular ridges on the inner surface of the ventricles are called

Why can't you use visible light to "see" molecules?

A system to maintain homeostasis must have at least four parts that function together. name these abd bruefly explain what each one does

Which of the following is a sac fungus? A rhizopus, B candida C penicillium notatum