It has been theorized that the organelles of eukaryotic cells evolved from prokaryotes living symbiotically within a larger cell. explain three lines of evidence that support this theory.

1. The presence of membrane- Organelles like mitochondria and plastids have their own cell membranes, just like a prokaryotic cell does,

2. The presence of DNA- Each of these organelles have its own DNA genome, like a bacteria's genome, but much smaller.

3. Reproduction (division)-Multiplication of the organelles occurs just like in bacteria, by division.

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.

common management practices in dairy and poultry farming are: (i) proper shelter facilities and their regular cleaning. (ii) some basic hygienic conditions such as clean water, nutritious food, etc. (iii) animals are kept in spacious, airy, and ventilated place.