1
MCQ (Single Correct Answer)
Which one of the following roles is not characteristic of an essential element?
A
being a component of biomolecules
B
changing the chemistry of soil
C
being a structural component of energy related chemical
D
activation or inhibition of enzymes
2
MCQ (Single Correct Answer)
Which one of the following statements can best explain the term critical concentration of an essential element?
A
essential element concentration below which plant growth is retarded
B
essential element concentration below which plant growth becomes enhanced
C
essential element concentration below which plant remains in the vegetative phase
D
None of the above
3
MCQ (Single Correct Answer)
Deficiency symptoms of an element tend to appear first in young leaves. It indicates that the element is relatively immobile. Which one of the following elemental deficiency would show such symptoms?
A
Sulphur
B
Magnesium
C
Nitrogen
D
Potassium
4
MCQ (Single Correct Answer)
Which one of the following symptoms is not due to manganese toxicity in plants?
A
Calcium translocation in shoot opex is inhibit
B
Deficiency in both iron and zitrogen induced
C
Appearance of brown spot surrounded by chlorotic veins
D
None of the above
5
MCQ (Single Correct Answer)
Reaction carried out by $\mathrm{N}_2$ fixing microbes include
(a) $2 \mathrm{NH}_3+3 \mathrm{O}_2 \longrightarrow 2 \mathrm{NO}_2^{-}+2 \mathrm{H}^{+}+2 \mathrm{H}_2 \mathrm{O}$ ............ (i)
(b) $2 \mathrm{NO}_2+\mathrm{O}_2 \longrightarrow 2 \mathrm{NO}_3$ ............. (ii)
Which of the following statements about these equations is not true?
A
Step (i) is carried out by Nitrosomonas or Nitrococcus
B
Step (ii) is carried out by Nitrobacter
C
Both steps (i) and (ii) can be called nitrification
D
Bacteria carrying out these steps are usually photoautotrophs