From Fig. $2.1$, the students obtained the Michaelis-Menten constant $K_m$ for enzyme A as $0.3\,\text{mmol dm}^{-3}$. Explain how they obtained $K_m$.
The students investigated another phosphatase enzyme (enzyme B) and found that $K_m$ was greater than $0.3\,\text{mmol dm}^{-3}$. Explain the difference between the $K_m$ values of these two phosphatase enzymes.
The students repeated their investigation on enzyme A using a competitive inhibitor. They kept the same substrate concentrations as before, but added a competitive inhibitor to each reaction mixture. The inhibitor concentration was the same in every reaction mixture. The students found that $V_{\max}$ was unchanged, but $K_m$ was greater than $0.3\,\text{mmol dm}^{-3}$. Explain how adding the competitive inhibitor gives the same value for $V_{\max}$ but a higher value for $K_m$.