In contrast: Protozoans are organisms usually made up a single cell and are all microscopic. All protozoans are eukaryotes. They have different responses when faced with adverse or unfavorable environmental conditions. Examples include:<span>Amoeba: During adverse environmental conditions, many amoeba undergo encystment that is they become cysts. The amoeba becomes circular, loses most of its water and secretes a thick membrane that serves as a protective covering. When the environment is again suitable, the covering of the cyst ruptures and the amoeba emerges. </span><span>Bacteria: In unfavorable environmental conditions some bacteria such as clostridium form spores, specifically endospores. An endospore is an extremely resistant, tough, dormant, non reproductive cell structure that can withstand desiccation, extreme temperatures, chemical disinfectants and starvation. The bacteria survive in this mode until better growth conditions return</span>
There are inner part of the stem and outer part of the stem; in a plant the inner part supports the movement of the water and nutrients. You stop the flow of the vital elements of plant growth when you snap the stem and this is the reason why the plant die due to starvation of the nutrients.
answer should be "making water hypoxic for organisms". reason is because the runoff from these treatment plants are filled with nutrients, which will cause eutrophication. eutrophication is excessive algae sprouts which create more DO but then later becomes all used up when they decompose, making it so other organisms have no oxygen.