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

Identify the element required by plants for utilization of calcium and pollen germination: