Cow's milk
No.
No.
You can test for starch in food by dropping iodine on food on an agar plate, if it turns black, it contains starch.
Spinach contains a small amount of iodine, but not significant enough to solely rely on it as a source of iodine in your diet. Other food sources such as iodized salt, seafood, and dairy products are better sources of iodine.
This is a classic biology experiment known as the "Iodine Test". Basically, by adding iodine (in the form of potassium iodide, KI) to something we can tell whether that something contains starch or not. If it turns dark blue (it's a very striking and obvious change, actually) then starch is present. So if there's no reaction, the food contains no starch. Coincidentally, it contains no Glycogen, either (as that would produce a brownish colour, albeit not the goal of the test). When doing this test, it's important to mulch up the food so any starches hidden on the inside (like in vegetable cells) is well exposed to give a perfectly reliable result.
If a food tested with an iodine indicator turns dark blue, it indicates the presence of starch. The iodine reacts with the starch molecules, forming a complex that results in the blue coloration. This test is commonly used to identify starch in various foods.
Yes, seawater contains trace amounts of iodine.
It is simply called the Starch test which is the process of testing something for the presence of starch. Add Iodine solution to whatever is it you're testing and a dark blue/black color indicates the presence of starch
Goiter is a condition of the thyroid gland (in the neck) caused by a deficiency of the element "Iodine" in the diet. Seawater/Sea salt contains Iodine and so do the animals that live in the sea. Therefore eating animals containing Iodine (sea food) will help prevent goiter.
yogurt contains iodine which can increase thyroid hormone production
Iodine is in salt
Tincture of iodine contains iodine and alcohol