Answer: Option C. -> Ni
:
C
Nickel was recently recognized as essential element as it was added to the list of essential plant nutrients only in the late 20th century. It acts as activator of urease and also helps with disease tolerance in plants. Mouse ear of pecan is a growth abnormality resulting from a deficiency of nickel in the pecan tree.

Answer: Option A. -> Cu, Mn and Fe
:
A
Both, photosynthetic and mitochondrial electron transport chains contain components that require Iron, Manganese and Copper for the electron transport to occur smoothly.

Answer: Option A. -> True
:
A
Thiobacillus and Pseudomonas convert nitrates to molecular nitrogen and release it into the atmosphere.

Answer: Option D. -> Leaching
:
D
Leachingrefers to the loss of water-soluble plant nutrients from thesoil, due to rain and irrigation.

:
The process of introducing molecular nitrogen of atmosphere into the living system in fixed form is called nitrogen fixation.

Answer: Option D. -> Sulphur
:
D
Sulphur is a componentof thiamine, biotin & CoA. Deficiency of sulphur in plants causes symptoms similar to the deficiency of nitrogen.

Answer: Option B. -> NO2, NO−3 or NH3
:
B
In nitrogen fixation molecular nitrogen is converted into nitrogen oxides like $N{O}_2^{-}$, $N{O}_3^{-}$through physical nitrogen fixation process or ammonia through biological or chemical processes.

Answer: Option B. -> A - 4, B - 2, C - 5, D - 1, E - 3
:
B
Nitrogen cycle involves five steps- nitrogen fixation, nitrogen assimilation, ammonification, nitrification and denitrification. The product of one step is the substrate for the next step.
$\begin{array}{cc}\text{Column - I}& \text{Column - II}\\ \text{A. Nitrogen fixation}& \text{4.Conversion of}{N}_{2}toN{O}_3^{-}\text{or}N{H}_3\\ \text{B. Nitrogen assimilation}& \text{2.Conversion of}N{O}_3^{-}\text{or}N{H}_3\text{to organic nitrogen}\\ \text{C. Ammonification}& \text{5.Conversion of organic nitrogen to}N{H}_3\\ \text{D. Nitrification}& \text{1.Conversion of}N{H}_3\text{to}N{O}_3^{-}\\ \text{E. Denitrification}& \text{3.Conversion of}N{O}_3^{-}\text{to atmospheric nitrogen}\end{array}$

Answer: Option B. -> False
:
B
Soil is a great reservoir for many minerals on this planet. Because of the mode of absorption of minerals in plants, most of the minerals in soil can enter the plants through their roots. Even though they might not have any role to play in the plant. Thus elements that have no role to play in plants have been found to be present in plants.

Answer: Option B. -> a – 3, b – 4, c – 2, d – 1
:
B
Manganese is involved in the breaking down the water molecule during photosynthesis.
Diazotrophy is the ability to fix atmospheric nitrogen into a biologically useful form. This is done with the help of the nitrogenase enzyme, which requires an iron-molybdenum cofactor.
Cytochrome c oxidase contains a copper center consisting of 2 copper atoms.
Zinc is required for the synthesis of auxins. Indole 3 acetic acid (IAA) is a prominentauxin.