The lock-and-key mechanism refers to
a. the complementary shapes of an enzyme and a substrate.
b. the attractive forces between an enzyme and a substrate.
c. the ability of an enzyme to lower the activation energy of a reaction.
d. the ability of an enzyme to “unlock” the products of a reaction.

the complementary shapes of an enzyme and a substrate.

stratosphere: as the altitude increases, the air temperature increases. the stratosphere has a layer of ozone, called the ozone layer. this layer absorbs most of the ultraviolet radiation from sunlight. this results in the stratosphere being warmer.