While traveling to a developing country, a group of students considers taking a swim in a forest lake. A stream runs into the lake. Upstream, the stream also runs
directly through a village. Assess the risk of worm infection the students take by
swimming in the water.

desert perennials often survive by remaining dormant during dry periods of the year, then springing to life when water becomes available. most annual desert plants germinate only after heavy seasonal rain, then complete their reproductive cycle very quickly.

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