A drug is administered intravenously at a constant rate of r mg/hour and is excreted at a rate proportional to the quantity present, with constant of proportionality > 0. (a) Solve a differential equation for the quantity, Q, in milligrams, of the drug in the body at time t hours. Assume there is no drug in the body initially. Your answer will contain r and . Graph Q against t. What is Q, the limiting long-run value of Q? (b) What effect does doubling r have on Q? What effect does doubling r have on the time to reach half the limiting value, 1 2Q ? (c) What effect does doubling have on Q? On the time to reach 1 2Q?

MICROBIOLOGY 210 – EXAM 3 STUDY GUIDE • TYPES OF SYMBIOSIS – living together o MUTUALISM – both organisms benefit o COMMENSALISM – one benefits, other is unaffected by the other’s presence o PARASITISM – one benefits, other is harmed...