MediumBiologyHigh School (9–10)GeneralHuman Body › Hormones and the Endocrine SystemNumericalapplication
A family's iodised salt has 30 mg of iodine in each kg, which is 30 micrograms in each gram…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A family's iodised salt has mg of iodine in each kg, which is micrograms in each gram. Each person eats g of salt a day and needs about micrograms of iodine a day. Is fresh salt enough? After a year in an open jar, the salt has lost of its iodine. Is it still enough?
Need a reminder? The key ideaShow
Endocrine glands release hormones into the blood. The pituitary makes growth hormone, the thyroid makes thyroxin (which needs iodine), the pancreas makes insulin (which lowers blood sugar), and the adrenal glands make adrenaline (which prepares the body for danger). Feedback keeps each level right.
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. Fresh salt. micrograms a day, more than the needed.
Step 2. Old salt. micrograms a day, less than .
Step 3. What it means. With old salt, the thyroid may not get enough iodine to make thyroxin, and over time goitre can develop.
Answer: fresh salt gives micrograms, which is enough; old salt gives only micrograms, which is not. Keep iodised salt in a closed jar.
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