In 2009, the h1n1 influenza virus caused illness around the world. an h1n1 virus was also responsible for the 1918 influenza epidemic, as well as an influenza outbreak in 1976. some people who were born before 1953 were found to have some immunity to the 2009 h1n1 virus. how could they have obtained this immunity?

the way that the mass of carbon can be conserved through cellular respiration is through a process/law called the law of conservation of mass which even tho it undergoes a process, mass is not be destroyed or changed

parasites can detrimentally affect their host, but also must not allow their host to die before they can complete their life cycle. some parasites have complex life cycles with many different hosts, and have had to find ways of persisting in many different environments during the change from one host to another. ectoparasites live outside the body of the host, and can more easily  disperse, but are  more exposed to predators, parasites, parasitoids. endoparasites live inside the body of the host, and are therefore protected from the outside environment. but they can be  attacked by the host's immune system. they have therefore developed  mechanisms for dispersal such as  complex life cycles.