In order to prove that magnesium is an essential salt for soybean life, two soybean seedlings with the same growth status are taken, one of them is cultured in magnesium-containing culture medium and the other is cultured in (). A. Pure water B. Sand without sand. Water containing only magnesium. Media containing no magnesium
Biological control experiments were the only variable experiments. The question that is being explored is the variable, and the other quantities are the same. In a different amount (conditions) the same circumstances to modify a data variable in order to get the data variables on the experimental changes in the law. In order to prove that magnesium is essential for the life of soybeans, the variable is the presence or absence of magnesium. Can be designed as a magnesium-containing culture medium and magnesium-free culture medium. The other amount of the same as the amount of culture medium, soybean seedling growth status, the same number, while placed in the same place, etc., to ensure that only one variable that is the presence of magnesium.
