What is the function of human heart? how blood circulate through it and other part of the body?

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.

Which of the following particles always has a positive charge? a. electronb. neutron c. proton d. ion

To confirm when to exclude children from school it’s recommended that you refer to guidelines from which of the following organizations