In a village without toilets, 40 people each carry 30 female hookworms ( Ancylostoma )…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
In a village without toilets, people each carry female hookworms (Ancylostoma). Suppose each female passes eggs a day (a made-up round number). (a) How many eggs reach the soil in a day? (b) In a week? (c) Why does wearing shoes protect people from this worm?
Need a reminder? The key ideaShow
Platyhelminthes: flattened, acoelomate, mostly parasites with hooks and suckers, flame cells, hermaphrodite; Taenia, Fasciola, Planaria (regeneration). Aschelminthes: round in section, pseudocoelomate, muscular pharynx, dioecious; Ascaris, Wuchereria, Ancylostoma. Annelida: metamerically segmented, coelomate, nephridia, closed circulation, double ventral nerve cord; Nereis has parapodia and is dioecious; Pheretima and Hirudinaria are monoecious.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. One day. eggs.
Step 2. One week. eggs.
Step 3. Shoes. Hookworm larvae grow in the soil and get in through the bare skin of the feet. Shoes block this way in.
Answer: (a) eggs; (b) eggs; (c) they stop the larvae in the soil from entering through the feet.
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