Final answer:
Malonyl CoA inhibits the entry of acetyl CoA into the mitochondrial matrix by inhibiting the enzyme carnitine palmitoyltransferase I (CPT-I).
Step-by-step explanation:
Malonyl CoA inhibits the entry of acetyl CoA into the mitochondrial matrix by inhibiting the enzyme carnitine palmitoyltransferase I (CPT-I). CPT-I is responsible for the transfer of acyl-CoA molecules into the mitochondrial matrix for fatty acid oxidation. By inhibiting CPT-I, malonyl CoA prevents the entry of fatty acids into the mitochondrial matrix for oxidation.