T/f: the main role of the respiratory system is gas exchange.

T

The lungs and respiratory system allow oxygen in the air to be taken into the body, while also enabling the body to get rid of carbon dioxide in the air breathed out. Respiration is the term for the exchange of oxygen from the environment for carbon dioxide from the body's cells.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products