What is an enzyme? Can you provide an example of an enzyme found in plants and describe its function? (4 marks)

An enzyme is a protein that is a biological catalyst (meaning it speeds up the rate of a reaction). The most abundant enzyme on earth, Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), is an enzyme found in plants which catalyzes the carbon fixation process in the light-independent photosynthetic reaction (otherwise known as the Calvin or Calvin-Benson cycle), where CO₂ is converted into useful energy-rich molecules for use by the plant.