In the given diagram of a typical set up for nutrient solution culture, the purpose of X is:

1. Addition of water 2. Addition of nutrients 3. Removal of wastes 4. Aeration

The most abundant intracellular cation is:
1. ${\mathrm{Na}}^{+}$
2. ${\mathrm{Ca}}^{++}$
3. ${\mathrm{H}}^{+}$
4. ${\mathrm{K}}^{+}$

Assertion: In some cases, sodium may be a ninth essential micronutrient.
Reason: Essential micronutrients are needed by the plants only in tiny quantities.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Assertion: The best defined function of manganese in plants is in the splitting of water to liberate oxygen during photosynthesis.
Reason: The oxygen evolving complex is a metallo-oxo cluster comprising four manganese ions (in oxidation states ranging from +2 to +4).

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Assertion: All nitrogen fixing organisms are bacteria.
Reason: Only bacteria can have mutualistic relationship with roots of plants.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

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 $\left({\mathrm{H}}_2{\mathrm{PO}}_4^{-}\mathrm{or}<mspace\; width="1em"></mspace>{\mathrm{HPO}}_4^{2-}\right)$
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 $\left({\mathrm{BO}}_3^{3-}\mathrm{or}<mspace\; width="1em"></mspace>{\mathrm{B}}_4{\mathrm{O}}_7^{2-}\right)$

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