<span>it has a specific activation site for enzyme attachment</span>
Reproductive isolating mechanisms are barriers which impeded mating (prezygotic) or prevent the hybrid from developing properly (postzygotic) but the overall effect is to cause speciation by making it difficult for two diverging species to share genes. So one kind of mechanical isolation could be the usage of contraceptives. As of temporal isolation, or behavioral isolation could be exemplified by people who suffer from diseases that cause separation (such as HIV or cancer). I hope that this is the answer that you were looking for and it has helped you.
Calcium. Calcium can be obtained from milk.
