Enzymes lower the activation energy for a chemical reaction to proceed.

The statement is true since one of the main functions of the enzyme is to lower the activation energy so that a chemical reaction to proceed.

Explanation:

Enzymes are specialized protein molecules that contribute to faster chemical reactions. One of the functional characteristics of an enzyme is that it reduces the activation energy for a reaction to occur.

Activation energy is the amount of net energy required for a reaction to occur. By lowering the activation energy, a reaction occurs faster, which is achieved with a biocatalyst such as enzyme.

4.) metal

"-the movement of carbon from the nonliving environment into living things and back to the environment

-carbon is the essential component of proteins, fats, and carbohydrates (which make up all organisms)

-carbon exists in air, water, and living organisms

-producers convert carbon dioxide in the atmosphere into carbohydrates during photosynthesis

-bacteria in the atmosphere cycles through the system in filtration units

-in cellular respiration, carbon is released back into the atmosphere as carbon dioxide

-some carbon is stored in limestone (forming one of the largest "carbon sinks" on earth)

-largest carbon reservoir on earth= limestone

-carbon stored in the bodies of organisms as fat, oils, or other molecules may be released into the soil or air when the organism dies

-this may form deposits of coal, oil, or natural gas (fossil fuels, which increased the atmospheric carbon dioxide)

-fossil fuels store carbon left over from bodies of organisms that died millions of years ago

-they are located in the surface of earth, deep within the earth and beneath the ocean floor."    

voluntary muscles are controlled by the cerebellum.