Soil Science - Study Mode

[#126] Root growth is particularly affected by
Correct Answer

(C) P

Explanation

Solution: Root growth is particularly affected by the availability of Phosphorus . It helps in encouraging plants to put down a dense collection of new roots and strengthen roots as they develop. The root is the most important plant part, it serves as the base of any plant, provides anchorage to the plant, along with the absorption of nutrients and water and conduction of these to the stem, also storage of reserve foods. Thus if roots are strong plants can sustain any harsh effects.

[#127] Which chemicals are responsible for host-specificity of Rhizobium?
Correct Answer

(C) Both A and B

Explanation

Solution: Flavonoids and Isoflavonoids are the chemicals responsible for the host-specificity of Rhizobium. Rhizobium is a genus of gram-negative soil bacteria that fix atmospheric nitrogen. The symbiotic association between rhizobium and legume is a highly specific interaction between the two partners. Host specificity is evident at the early stages of infection and results from multiple interactions involving signaling among bacteria and host plants.

[#128] In a muck soil or soil having higher organic matter content, which deficiency of which element will be encountered first?
Correct Answer

(B) Cu

Explanation

Solution: In a muck soil or soil having higher organic matter content, deficiency of Copper (Cu) is encountered first. A muck soil is usually a peat deposit that has drained and cultivated and in which the surface layer has undergone considerable oxidation and disintegration of the original peat fibres.n it is sapric soil that is naturally waterlogged or artificially drained.

[#129] Which process is also called as 'Dissimilatory Nitrate Reduction'?
Correct Answer

(C) Denitrification

Explanation

Solution: Denitrification is the process that is also known as "Dissimilatory Nitrate Reduction." Which refers to the conversion of nitrate by using it as an electron acceptor. Denitrification is a microbially facilitated process where nitrate is reduced and ultimately produces molecular nitrogen (N 2 ) through a series of intermediate gaseous nitrogen oxide products. Complete denitrification serves as an efficient N-removal pathway in the environment.

[#130] To prepare 250 mL 0.5N NaOH solution, NaOH needed is
Correct Answer

(A) 5g

Explanation

Solution: To prepare 250 mL 0.5N NaOH solution, $${ ext{No}}{ ext{.}},{ ext{of}},{ ext{moles}}left( { ext{n}}
ight) = frac{{{ ext{Molarity}} imes { ext{V}}left( {{ ext{ml}}}
ight)}}{{1000}}$$ Given, volume of the solution = 250 ml M = 0.5 M Therefore, No.of moles (n) $$eqalign{
& = frac{{0.5 imes 250}}{{1000}} cr
& = frac{{125}}{{1000}} cr
& = 0.125{ ext{ mol}} cr} $$ Molar mass of NaOH = 40g Mass of NaOH required in grams $$eqalign{
& = 0.125 imes 40 cr
& = 5,{ ext{g}} cr} $$