6. Which of these statements is true of the fossil record?
A. The fossil record contains a
complete record of every extinct
organism.
B. The fossil record contains mostly
soft organisms that had no hard
bones or outer shells.
C. Newer layers contain organisms
more similar to modern-day
organisms than do older layers
D. Older layers contain organisms
more similar to modern-day
organisms than do newer layers

1. an enzyme is considered a(n) because it speeds up a chemical reaction without being used up.2. in a catalyzed reaction, a reactant is often called a(n) . an enzyme is specific because the shape of its matches only particular reactants.4. an enzyme speeds up reactions by lowering the . the between an active site and its substrate often strains bonds and the reaction proceed.6. a( , which is often a vitamin, binds to an enzyme and plays a role in catalysis.7. high temperatures or changes in ph can an enzyme, causing it to lose its shape and biological activity.