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Mineral Nutrition · Question 22

NEET 2013 (Karnataka)MCQMedium📈 Topic in 25% papers+4−1
1

Which two distinct microbial processes are responsible for the release of fixed nitrogen as dinitrogen gas (N2) to the atmosphere?

  1. Aerobic nitrate oxidation and nitrate reduction
  2. Decomposition of organic nitrogen and conversion of dinitrogen to ammonium compounds
  3. Enteric fermentation in cattle and nitrogen fixation by Rhizobium in root nodules of legumes
  4. Anaerobic ammonium oxidation and denitrification

Answer

(4) Anaerobic ammonium oxidation and denitrification

Solution

Fixed nitrogen returns to the atmosphere as N2 by:

(i) Denitrification — nitrate is reduced to N2 by bacteria such as Pseudomonas and Thiobacillus (as per NCERT).

(ii) Anaerobic ammonium oxidation (anammox) — NH4+ + NO2- N2 + 2H2O.

Nitrogen fixation and ammonification do the opposite (add fixed nitrogen).

Answer: (4)

Out of syllabusNEET 2013 (Karnataka)

Keep practising — Mineral Nutrition

2

For its action, nitrogenase requires

  1. high input of energy
  2. light
  3. Mn2+
  4. super oxygen radicals
Out of syllabusAIPMT 2012 (Mains)
3

Which one of the following is wrong statement?

  1. Anabaena and Nostoc are capable of fixing nitrogen in free-living state also.
  2. Root nodule forming nitrogen fixers live as aerobes under free-living conditions.
  3. Phosphorus is a constituent of cell membranes, certain nucleic acids and all proteins.
  4. Nitrosomonas and Nitrobacter are chemo-autotrophs.
AIPMT 2012 (Prelims)
4

Best defined function of manganese in green plants is

  1. photolysis of water
  2. Calvin cycle
  3. nitrogen fixation
  4. water absorption
Out of syllabusAIPMT 2012 (Prelims)
5

Which one of the following is correctly matched?

  1. Passive transport of nutrients – ATP
  2. Apoplast – Plasmodesmata
  3. Potassium – Readily immobilisation
  4. Bakane of rice seedlings – F. Skoog
Out of syllabusAIPMT 2012 (Prelims)
6

Which one of the following is essential for photolysis of water?

  1. Copper
  2. Manganese
  3. Boron
  4. Zinc
AIPMT 2011 (Mains)
7

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

  1. Iron
  2. Manganese
  3. Cadmium
  4. Phosphorus
Out of syllabusAIPMT 2011 (Mains)
8

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

  1. Phosphorus
  2. Calcium
  3. Potassium
  4. Sulphur
Out of syllabusAIPMT 2011 (Prelims)
9

Nitrifying bacteria

  1. oxidize ammonia to nitrates
  2. convert free nitrogen to nitrogen compounds
  3. convert proteins into ammonia
  4. reduce nitrates to free nitrogen
Out of syllabusAIPMT 2011 (Prelims)
10

The function of leghaemoglobin in the root nodules of legumes is

  1. inhibition of nitrogenase activity
  2. oxygen removal
  3. nodule differentiation
  4. expression of nif gene
Out of syllabusAIPMT 2011 (Prelims)
11

Leguminous plants are able to fix atmospheric nitrogen through the process of symbiotic nitrogen fixation. Which one of the following statements is not correct during this process of nitrogen fixation?

  1. Leghaemoglobin scavenges oxygen and is pinkish in colour.
  2. Nodules act as sites for nitrogen fixation.
  3. The enzyme nitrogenase catalyses the conversion of atmospheric N2 to NH3.
  4. Nitrogenase is insensitive to oxygen.
Out of syllabusAIPMT 2010 (Mains)

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