Mineral Nutrition

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

1. carotene
2. cytochrome
3. leghaemoglobin
4. xanthophyll.

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

1. potassium, phosphorus, selenium, boron
2. magnesium, sulphur, iron, zinc
3. phosphorus, potassium, sulphur, calcium
4. calcium, magnesium, manganese, copper.

Deficiency symptoms of nitrogen and potassium are visible first in

1. senescent leaves
2. young leaves
3. roots
4. buds.

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

1. NO3-
2. glutamate
3. NO2-
4. ammonia.

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

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

Which of the following elements is a constituent of biotin?

1. Magnesium
2. Calcium
3. Phosphorus
4. Sulphur

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

For its action, nitrogenase requires

1. high input of energy
2. light
3. Mn2+
4. super oxygen radicals

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.

Best defined function of manganese in green plants is

1. photolysis of water
2. Calvin cycle
3. nitrogen fixation
4. water absorption