Question

use the graph and your knowledge of enzymes to identify the three true statements about enzymes. only reactions that are controlled by enzymes require activation energy. enzymes lower the overall energy input needed for a reaction to occur. chemical reactions cannot occur without enzymes. reactants cannot convert to products without an initial input of energy to start the reaction. by binding to reactant molecules, enzymes make it easier for the bonds in the molecules to break apart.

Explanation:

• All chemical reactions require activation energy, not just those controlled by enzymes, so the first statement is false.
• Enzymes are catalysts that lower the activation - energy barrier, thus reducing the overall energy input needed for a reaction, making the second statement true.
• Many chemical reactions can occur without enzymes, so the third statement is false.
• Reactants generally need an initial input of energy (activation energy) to start a reaction, making the fourth statement true.
• Enzymes bind to reactant molecules (substrates) and through induced - fit and other mechanisms, make it easier for bonds in the molecules to break apart, making the fifth statement true.

Answer:

• Enzymes lower the overall energy input needed for a reaction to occur.
• Reactants cannot convert to products without an initial input of energy to start the reaction.
• By binding to reactant molecules, enzymes make it easier for the bonds in the molecules to break apart.