Here are some things you missed on the quiz and we think you should review.
Biology/Biochemistry
You should recognize that enzymes typically end with –ase and so you can see that the figure provided indicates the 3 enzymes that are catalysts for the three reactions as shown.
Understanding Ornithine >
Biology/Biochemistry
On the Surface: In the previous question, we established that the enzyme argininosuccinase must be functional for both strains and that means that argH is not defective (no mutation) for either P or Q. Thus any answer choice suggesting an argH mutation is incorrect.