The diagram below represents the chemical pathway of a process in a human liver cell.
Substance A
Step 1
enzyme X
energy
Step 2
Substance B
enzymeY
energy
Substance C
4.
A particular liver cell is unable to make substance C. One possible explanation for the
inability of this cell to make substance C is that
O a mutation occurred causing a change in the ability of the cell to use substance C.
excess energy for step 2 prevented the conversion of substance B to substance C.
an excess of enzyme X was present, resulting in a decrease in the production of substance B.
nuclear DNA was altered resulting in the cell being unable to make enzyme Y