Which of the following statements is true of nuclear fusion? a. it must take place at extremely high temperatures. b. it must take place in low-density containers. c. it results in nuclei that are lighter in weight than the nuclei that existed before the reaction. d. it does not release a great amount of energy.

Animal bodies (and even plant bodies for that matter) are complex enough that life couldn't exist without enzymes. enzymes are usually large, complex biological catalysts that are expensive to make. enzymes speed up the rate of chemical reactions without being used up during the reaction (they can be reused many times). they are highly specific in the reactions they regulate. knowing what enzymes are and how they function, why does this explain why complex life forms could not exist if there were no enzymes.

Agroup of organisms that changes over time is said to

These are the components of the reservoirs of carbon that are exchanged in our environment.