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.

You are performing cpr by yourself. the aed advises a shock. after the shock is delivered, what is the next immediate step?

Precaustions to thundstorms

Can goldfish and tadpoles live in the same outdoor pond

Which of the following are true of genes? a. They blend together at the level of genotype b. They code for a protein c. Through mutation they come in new forms such as "jeggings" d. None of the above

Young tadpoles breath like fish. what structure enables them to breathe underwater A. tracheae B. skin C. alveoli D. gills

A "red-hot" bacterial infection of the intestinal tract irritates the intestinal cells and interferes with digestion. such a condition is often accompanied by diarrhea, which causes loss of body water.

Which of Mendel's laws BEST explains why genetic variations occur in offspring resulting from sexual reproduction? A law of segregation B law of dominance C law of independent assortment D law of crossing-over

When can a primary succession occur?

Friction between a skateboard wheel and the surface produces?

What are two functions of the cell membrane