Ch. 2 : “Chemistry of Life”

Directed Reading: “Energy and Chemical Reactions”

Short Answer

1. Why is energy important to living things? Energy powers the chemical reactions in

cells.2. How does the energy in food become

available to organisms? The energy in food becomes available to

organisms through chemical reactions.

Matching3. energy:e. the ability to move or change matter4. reversible reaction:d. can proceed in the opposite direction5. products:a. ending materials in a chemical reaction

Matching6. chemical reaction:c. chemical bonds between atoms are

broken and new ones are formed7. activation energy:b. energy needed to start a chemical

reaction8. reactants:f. beginning materials in a chemical reaction

Explain the difference.

9. energy-releasing reaction, energy-absorbing reaction

The reactants of an energy-releasing reaction contain more energy than the products. The reactants of an energy absorbing reaction contain less energy than the products.

Explain the difference.

10. reactants, products Reactants are the starting materials for a

chemical reaction. Products are the ending materials of a chemical reaction.

Define

11. What is a catalyst? Catalysts are substances that reduce the

activation energy needed for chemical reactions.

12. What is an enzyme? Enzymes are substances that increase the

speed of chemical reactions.

Fill in the blank.13. A substance on which an enzyme acts is called

a(n) ___. substrate14. Hydrogen ___ is a substrate of the enzyme

catalase. peroxide15. A(n) ___ is the part of the enzyme into which

the substrate fits. active site