Question

Which of the following is not a non-essential element for plants?
a. Potassium
b. Sodium
c. Aluminum
d. Cobalt

Answer 1

An element is said to be essential for plants if plants cannot complete their life cycle without that element, and this element directly involved in some many functions of plants, if these essential elements are required for plants in large amounts, then it is a macronutrient and if it is required for small amounts, then it is called micronutrient.

Complete answer:
Plants require sunlight, water, and other essential elements for photosynthesis. There are mainly 20 essential elements for the plants.
- An element is considered as essential if they have following features
- The element should be essential for the plant, to complete its life cycle.
- That essential element cannot be replaced by any other elements.
- The function of the element is very important to obtain nutrition.
- Carbon, hydrogen and oxygen are very essential to produce the carbohydrates by a process called photosynthesis.

Macro elements	Microelements
Carbon	Iron
Hydrogen	Manganese
Oxygen	Boron
Nitrogen	Molybdenum
Phosphorus	Copper
Potassium	Zinc
Calcium	Chlorine, Nickel
Magnesium	Cobalt, sodium
Sulfur	Silicon.

- Nitrogen is the component of many essential amino acids, and it plays a very important role in protein synthesis.
- In phosphorus it is very essential to produce energy such as ATP by phosphorylation, and this phosphorus is important for the structure of cell membranes.
- Whereas potassium is essential because it plays an important role in the opening and closing of Stomata and maintains the water balance in the plants.
- Calcium and magnesium are the important components of the plant enzymes and they also play an important role in maintaining the ionic balance.
- Sulfur is the component of some of the amino acids such as cysteine and methionine and these amino acids are present as cofactors or coenzymes in so many reactions of the plants.
- Apart from the macronutrients, they also require some other essential elements in minor quantities for the plant growth and development.
- From the above given options they asked for which is not non- essential, which means they are asking which one essential, so potassium essential macronutrient.

Hence, the correct answer is option (A).

Note: Deficiency of any of the essential elements of the plants, especially macronutrients may cause so many adverse effects, which includes stunted growth, or any slow growth, and it may show chlorosis, sometimes in extreme conditions, it may show signs of cell death.