28. Which is one of the essential nutrients for the growth and development of plants?

[A] Potassium
[B] Phosphorus
[C] Nitrate
[D] Sodium

For each of the following elements, indicate whether it is a macronutrient, a micronutrient, or neither, and state what its primary function is in plant growth and development.

1) Iron

2) Carbon

3) Nitrogen

4) Zinc

5) Phosphorus

6) Oxygen

What are the differences between essential, nonessential, andconditionally essential nutrients? Describe an example of asituation in which a non-essential nutrient becomes conditionallyessential.