Enzymes are biological catalysts that can function either within the cells that produce them (intracellularly) or after being secreted into the external environment (extracellularly).
Which of the following processes is catalysed by an extracellular enzyme?
Synthesis of aminoacyl-tRNA by aminoacyl-tRNA synthetase in the cytoplasm
Breakdown of elastin in alveolar walls by elastase secreted by neutrophils
Phosphorylation of glucose by hexokinase in the cytosol
Cleavage of hydrogen peroxide into water and oxygen by catalase in peroxisomes
9 exam-style questions on OCR A A Level Biology Enzymes. Each one has a worked solution and a mark scheme showing where the marks go.