PLEASE HELP!! IM STRUGGLING LOL All chordates have:
A. A single, dorsal, tubular, nerve cord
B. All of these
C. A dorsal heart
D. pharyngeal gill slits used for respiration

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.

Need will mark ! which features are created by groundwater erosion and deposition? check all that apply. a. stalagmitesb. sinkholesc. rillsd. stalactites e. gullies f. rivers

An easy way to calculate the amount of energy available at each level is to what?