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 Multiple Choice QuestionsMultiple Choice Questions


Consumption of which one of the following foods can prevent the kind of blindness associated with vitamin ‘A’ deficiency?

  • ‘Flaver Savr’ tomato

  • Canolla

  • Golden rice

  • Bt-Brinjal


Golden rice

Golden rice is a variety of Oryza sativa (rice) produced through genetic engineering to biosynthesize Beta-acetone, a precursor of vitamin-A in the edible part of rice (i.e., endosperm). The research that led golden rice was conducted with the goal of helping children who suffer from vitamin-A deficiency. Because many children in countries where there is a dietary deficiency in vitamin-A rely on rice as a staple food, the genetic modification of rice to produce the vitamin-A precursor beta-carotene is seen as a simple and less expensive alternative to vitamin supplements. 



The first stable product of fixation of atmospheric nitrogen in leguminous plants is

  • NO2-

  • ammonia

  • NO3-

  • glutamate



The process of conversion of nitrogen (N2) to ammonia is termed as nitrogen fixation.

stack straight N subscript 2 with left parenthesis nitrogen right parenthesis below space rightwards arrow stack straight N subscript 2 straight H subscript 2 space with Dimide below rightwards arrow stack straight N subscript 2 straight H subscript 4 with Hydrazine below rightwards arrow 2 stack NH subscript 3 with ammonia below

2 NH subscript 3 space plus 3 straight O subscript 2 space rightwards arrow 2 NO subscript 2 superscript minus plus 2 straight H to the power of plus plus 2 straight H subscript 2 straight O
2 NO subscript 2 space plus straight O subscript 2 space rightwards arrow space 2 NO subscript 3 superscript minus
In reductive animation, ammonia reacts with alpha-ketoglutaric acid and forms glutamic acid alpha-ketoglutaric acid +NH4+ +NADPH

rightwards arrow from Dehyrogenae to Glutamate of space Glutamate space plus straight H subscript 2 straight O space plus NADP



An element playing important role in nitrogen fixation is 

  • Molybdenum

  • copper

  • manganese

  • zinc



Molybdenum is absorbed as molybdate by plants. It is involved in nitrogen metabolism including nitrogen fixation. It is a component of enzyme nitrogenase and acts as an enzyme activator. Its deficiency cause chlorosis and necrosis, whiptail of cauliflower and premature leaf fall. 

Copper is absorbed by the plant in ionic form. Its deficiency causes necrosis, die back in Citrus, reclamation in legumes.

Manganese is absorbed by the plants as a bivalent ion. It acts as the enzyme activator. Its deficiency causes interveinal chlorosis as well as yellowing of starch and their subsequent degenerate. 

Zinc is needed for biosynthesis of IAA and also acts as the enzyme activator. Its deficiency causes chlorosis, little leaf, rosette, the white bud of maize and mottling of leaves.



Which one of the following elements in plants is not remboilised?

  • Calcium

  • Potassium

  • Sulphur

  • Phosphorus



An element like calcium are a part of a structural component of the cell and hence, are not released. The deficiency symptoms tend to appear first in the young tissue whenever the elements are not demobilised.



Best defined function of manganese in green plants is

  • Photolysis of water

  • Calvin cycle

  • Nitrogen fixation

  • Water absorption


Photolysis of water

Photolysis of water requires light energy, an Oxygen-Evolving Complex (OEC) and electron carrier 1/2. OEC complex was formerly called Z-enzyme. It has four Mn ions. Light energy brings about changes in Mn (Mn+2,  Mn3+,  Mn+4) which helps in removing electrons from OH- component of water forming oxygen. Liberation of oxygen also requires Cl- and Ca+2.



In which of the following, all three are macronutrients

  • Iron, copper, molybdenum

  • Molybdenum, magnesium, manganese

  • Nitrogen, nickel, phosphorous

  • Boron, zinc, manganese


Nitrogen, nickel, phosphorous

Option c is the most appropriate as it has two macronutrients. 



Minerals known to be required in large amounts for plant growth include

  • phosphorus, potassium, sulphur, calcium

  • calcium, magnesium, manganese, copper

  • potassium, phosphorus, selenium, boron

  • magnesium, sulphur, iron, zinc


phosphorus, potassium, sulphur, calcium

Minerals known to be required in large amounts for plant growth are macronutrients. According to question, option (a) is correct, i.e., phosphorus, potassium, sulphur, calcium.
Macronutrients are consumed in large quantities and are required for plant tissue from 0.2% to 0.4% (on dry matter weight basis). Following are the rest of the macronutrients as:
carbon, hydrogen, oxygen, nitrogen, magnesium, silicon. 



Which one of the following is not an essential mineral elements for plants while the remaining three are?

  • Iron

  • Manganes

  • Cadmium

  • Phosphorus



Cadmium is not essential elements to plants



For its action, nitrogenase requires

  • high input of energy

  • light

  • Mn2+

  • super oxygen radicals


high input of energy

The enzyme nitrogenase is a Mo-Fe protein and catalyses the conversion of atmospheric N2 to NH3 as
straight N subscript 2 plus 8 straight e to the power of minus plus 8 straight H to the power of plus plus 16 ATP space rightwards arrow space 2 NH subscript 3 plus straight H subscript 2 plus 16 ADP plus 16 straight P subscript straight i
Enzyme nitrogenase functions under anaerobic condition and the pigment leghaemoglobin protect it from oxygen. 



During biological nitrogen fixation inactivation of nitrogenase by oxygen poisoning is prevented by

  • Leghaemogolobin

  • Xanthophyll

  • Carotene

  • Cytochrome



During biological nitrogen fixation, inactivation of nitrogenase  by oxygen poisioning is prevented by leghaemoglobin.
It is a  red-pigment that is filled outside the peribacteroid space in the cytosol of nodule cells. It has the ability to combine very rapidly with oxygen and thus acts a very efficient O2 scavenger.