Final answer:
Enzymes are protein-based biological catalysts that speed up chemical reactions by lowering the activation energy, without being consumed by the reaction or altering ΔG. They are specific to their substrates, meaning each enzyme functions with particular reactant molecules. So, tghe correct answer is A.
Step-by-step explanation:
Understanding Enzymes
Enzymes are vital biological catalysts that are predominantly protein in nature. They are responsible for speeding up the rate of chemical reactions by lowering the reaction's activation energy. An enzyme's ability to lower activation energy is crucial for bodily functions because it allows reactions to proceed quickly enough to sustain life. The specificity of an enzyme to its substrate is fundamental to its function, with each enzyme only being able to bind to particular substrate(s) it is compatible with.
The statement that 'enzymes increase ΔG of reactions' is not true. ΔG, or Gibbs free energy, is a measure of the spontaneity of a reaction, and enzymes do not affect the overall ΔG of a reaction, but simply lower the energy barrier required to reach the transition state, thus speeding up the process.
Enzymes are generally composed of amino acids and are not consumed during the chemical reactions they catalyze. The specificity of enzymes means that they are designed to bind only with specific substrates, ensuring that chemical reactions within the body are regulated and proceed as necessary.