12. The enzyme in cholesterol biosynthesis subject to feedback inhibition is(A)ABCB4.(B)desaturase.(C)fatty acid synthase.(D)HMG CoA reductase.

6. Which one of the following statements is true about catabolic pathways?(A)They combine molecules into more complex and energy-rich molecules.(B)They belong to the reduction reaction.(C)They are usually coupled with anabolic pathways and generate energy in the form of ATP.(D)They do not need enzyme catalysts.