Question 10
A plant's growth is stunted and its mature leaves show chlorosis. Which mineral salt is it short of?
The right answer is the one marked above.
Nitrogen. In plants it works as a component of amino acids, proteins, nucleic acids, enzymes and chlorophyll — so a shortage stunts growth and yellows the older leaves.
Read the position of the chlorosis, not just the fact of it: nitrogen shortage shows in the mature leaves, iron shortage in the young ones, and sulphur shortage in and near the leaf veins.