Fundamentals of Plant Nutrition MCQs Quiz 19

1. In most agricultural soils, rapid organic matter decomposition is dominated by _______

 Protozoa as primary decomposers of complex polymers

 Exclusive activity of lignin-degrading fungi only

 Aerobic bacteria and fungi utilizing oxygen as the terminal electron acceptor

 Obligate anaerobes active under oxygen-limited conditions

2. Sandy soils are more prone to nutrient losses mainly due to _______

 High microbial activity

 High leaching

 Low permeability

 High clay content

3. Nutrient ion uptake across plant cell membranes is fastest through _______

 Ion pumps

 Ion channels

 Carrier proteins

 General transport proteins

4. Heavy metals that also function as plant nutrients include _______

 Pb and As

 Ni and Zn

 Cd and Hg

 Fe and Pb

5. Yellowing of leaves cause by nitrogen deficiency is called _______

 Chlorosis 

 Etiolation

 Wilting

 Necrosis

6. The high phloem mobility of potassium in plants allows it to _______

 Form stable organic complexes in cell walls

 Be readily retranslocated from mature to actively growing tissues

 Remain fixed in older tissues as a structural component

 Accumulate only in roots with limited shoot transport

7. Ammonification is a key microbial process in the nitrogen cycle, involving  _______________________

 Release of ammonium from organic nitrogen compounds

 Conversion of ammonia to nitrate

 Loss of ammonia to the atmosphere

 Fixation of ammonium in clay minerals

8. The high nitrogen concentration of urea fertilizer is primarily due to _______

 Inclusion of ammonium and nitrate ions

 Presence of two amide (–NH₂) groups in the molecule

 Its nitrate-based chemical composition

 Association with organic carbon polymers

9. A low C:N ratio crop residue (e.g., legumes) typically results in _______

 No microbial activity

 Carbon limitation

 Nitrogen immobilization

 Nitrogen mineralization

10. With increasing soil pH (alkaline conditions), the dominant plant-available phosphate species shifts toward _______

 Polyphosphate chains formed in solution

 HPO₄²⁻ due to decreased proton activity

 H₂PO₄⁻ due to proton enrichment

 Organic phosphate complexes in humus

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Fundamentals of Plant Nutrition MCQs Quiz 19