Multiple choice Which among the following is a primary macronutrient required by the plants? Magnesium Silicon Calcium Phosphorus Sulphur Reveal answer Fill a bubble to check yourself D Correct answer Explanation Phosphorus is important in plant bioenergetics. As a component of ATP, phosphorus is needed for the conversion of light energy to chemical energy (ATP) during photosynthesis. It is a primary macronutrient of the plants.