An element that is labeled as ‘essential’ for plants is characterized by all the following except:
1. Its deficiency cannot be met by supplying some other element
2. It allows normal vegetative growth but does not allow seed set, if absent
3. Its requirement must be specific
4. It must be directly involved in the metabolism of the plant

The minimum amount of requirement for an element to be classified as a macronutrient for plants is:
1. 5 mmole ${\mathrm{kg}}^{-1}$ of dry matter
2. 10 mmole ${\mathrm{kg}}^{-1}$ of dry matter
3. 20 mmole ${\mathrm{kg}}^{-1}$ of dry matter
4. 40 mmole ${\mathrm{kg}}^{-1}$ of dry matter

Which of the following element required by the plants is a micronutrient?

Identify the incorrect statement amongst the following:
1. Phosphorus is obtained by the plants from the soil in the form of phosphates $\left({\mathrm{H}}_2{\mathrm{PO}}_4^{-}\mathrm{or} {\mathrm{HPO}}_4^{2-}\right)$
2. Nitrogen is obtained from the soil in the form of nitrates $\left({\mathrm{NO}}_3^{-}\right)$ , nitrites $\left({\mathrm{NO}}_2^{-}\right)$ and ammonium $\left({\mathrm{NH}}_4^{+}\right)$ salts
3. Sulphur is mainly obtained by plants as sulphur dioxide by foliar absorption
4. Boron is absorbed in the form of borate ions $\left({\mathrm{BO}}_3^{3-}\mathrm{or} {\mathrm{B}}_4{\mathrm{O}}_7^{2-}\right)$

${\mathrm{Zn}}^{2+}$ is an activator of the enzyme:

An essential element categorized in elements that can alter the osmotic potential of a cell will be:

Identify the element that is not obtained by terrestrial plants primarily from soil?

A plant requires magnesium mainly for:

Which of the following elements is a constituent of vitamins such as thiamine, biotin and Coenzyme A?

The two elements required for splitting of water to liberate oxygen during photosynthesis are:
1. Manganese and Chlorine
2. Manganese and Boron
3. Copper and Chlorine
4. Molybdenum and Magnesium