Final answer:
Lead inhibits the enzymes ALAD and ferrochelatase, which are important in the heme synthesis pathway, contributing to sideroblastic anemia.
Step-by-step explanation:
Lead poisoning affects the enzymes ALAD (aminolevulinic acid dehydratase) and ferrochelatase, which are critical in the heme synthesis pathway. The correct answer to how lead affects these enzymes is: Lead inhibits the activity of ALAD and ferrochelatase. Inhibition of ALAD leads to poor conversion of aminolevulinic acid to porphobilinogen, subsequently affecting the whole chain of heme synthesis. Ferrochelatase is the final enzyme in the heme pathway, and its inhibition by lead prevents the incorporation of iron into protoporphyrin IX to form heme. This disruption in heme synthesis contributes to the development of sideroblastic anemia, among other adverse health effects.