The protist, plasmodium, can invade and live in the blood of animals, causing the disease malaria. this shows which type of interaction between the protist and the animal?

Plasmodium species causes malaria in humans. It is also called as a malaria parasite. Its life cycle involves two hosts, mosquitoes and humans. Mosquitoes get malaria from biting a human who has malaria. The mosquito draws the blood into its stomach where malaria parasites breed and infect other red blood cells. Humans get malaria from a bite by an infected mosquito. This bite injects malaria-causing parasites into your blood, where they travel to liver cells. In the liver cells, the parasites breed. The interaction between Plasmodium and its host is parasitism. Plasmodium takes nutrition from the host and harm them. Therefore, Plasmodium is a parasite.    

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products

when it is at an intermediate population density