<span>Pokaryotes are single cell organisms. Anaerobic prokaryotes use oxygen to obtain energy.</span><span> They use oxygen to perform cellular respiration, so they perform anaerobic respiration.
</span>
<span>Archaea
and eubacteria are prokaryotic in nature. One of the differentiating
characteristics between them is that eubacteria have peptidolycan in their cell
walls.</span>
Answer:
Because the trophozoites are unable to survive outside a host.
Explanation:
The term infectious is used for a disease or microorganism that can be transmitted from one organism to the other organism through the environment. If we look at the two forms of Giardia, we find that out of the two forms viz. cysts and trophozoites, only the cysts of Giardia have the ability to remain alive in the environment outside the host and thus they are able to be transmitted to the other organisms. On the other hand trophozoites are not able to survive in outside environment so there is no chance of transmission of trophozoites.
