What is it called when changes occur in an ecosystem that already exists? *

a. primary succession

b. secondary succession

c. pollution

What organic molecules catalyze chemical reactions

Which of the following is an example of a renewable resource? a. coal b. oil c. gas d. water

What is the final energy source that the muscles need in order to move? a. fat b. sugar c. ATP d. glycogen

8 P O I N T S! Which of the following is a characteristic of a scientific experiment? Its results always support the hypothesis. It shows cause and effect relationships. It is performed in nature. It can be performed only once.

Anne was observing a cell under a microscope which was undergoing binary fission. Which type of cell was Anne observing? Select one of the options below as your answer. A. Eukaryotic animal cell B. Eukaryotic plant cell C. Prokaryotic cell.

Ice sheets are in enormous masses of ice that

Why are infections more common with compound fractures than with simple fractures?

Humanity adds about 5.5 billion tons of of carbon dioxide per year, most of which goes directly into the atmosphere. What is this doing to the atmosphere?

Brad steps onto a bathroom scale, exerting a downward push of 150 pounds. What force doel the scale exert onto Brad?

Why do birth control pills contain hormones?