He lock-and-key mechanism refers to the complementary shapes of an enzyme and a substrate. the attractive forces between an enzyme and a substrate. the ability of an enzyme to lower the activation energy of a reaction. the ability of an enzyme to "unlock" the products of a reaction.

answercells,tissues,organs,organ,system-organism;

levels of biological organization; organism,population,community,ecosystem,biome,biosphere,

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yes. we have only a limited amount of land and space, and every plant is adapted to its own environment. through gene manipulation, we could perhaps create plants that can grow in a wide variety of environments, grow taller or wider, or be more resistant to diseases.

(this is the exact answer provided by the system)