Mineral Nutrition — Page 7 | NEET Biology

Q61

For its action, nitrogenase requires

A Mn2+

B light

C high input of energy

D super oxygen radicals

Correct Answer

Option C

Solution

(c) Nitrogenase requires high energy input (16 ATP per N2 molecule) and anaerobic conditions.

Q62

For its activity, carboxypeptidase requires

A zinc

B iron

C niacin

D copper

Correct Answer

Option A

Solution

(a) Carboxypeptidase is an exopeptidase enzyme secreted by the pancreas that acts only on the peptide linkage of a terminal amino acid containing a free carboxyl group.

Zinc is a cofactor for carboxypeptidase.

In Digestion of carboxypeptidase, requires zinc for its protein degrading action.

Q63

Which one of the following is wrong statement?

A Anabaena and Nostoc are capable of fixing nitrogen in free living state also

B Root nodule forming nitrogen fixers live as aerobes under free-living conditions.

C Phosphorus is a constituent of cell membranes, certain nucleic acids and cell proteins.

D Nitrosomonas and Nitrobacter are chemoautotrophs.

Correct Answer

Option C

Solution

(c) Phosphorus is a constituent of nucleic acids but absent from cell proteins.

Q64

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

A Anaerobic ammonium oxidation, and denitrification

B Aerobic nitrate oxidation, and nitrite reduction

C Decomposition of organic nitrogen, and conversion of dinitrogen to ammonium compounds

D Enteric fermentation in cattle, and nitrogen fixation by Rhizobium in root nodules of legumes

Correct Answer

Option A

Solution

(a) Anaerobic ammonium oxidation (anammox) and denitrification both release N2 to atmosphere.

Q65

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

A Ammonia

B NO3-

C Glutamate

D NO2-

Correct Answer

Option A

Solution

(a) Ammonia is the first stable compound produced during biological nitrogen fixation.

Q66

Thiobacillus is a group of bacteria helpful in carrying out:

A Nitrogen fixation

B Chemoautotrophic fixation

C Nitrification

D Denitrification

Correct Answer

Option D

Solution

(d) Thiobacillus denitrificans causes denitrification.

Q67

Which of the following bacteria reduce nitrate in soil into nitrogen?

A Nitrosomonas

B Nitrobacter

C Nitrococcus

D Thiobacillus

Correct Answer

Option D

Solution

(d) Thiobacillus denitrificans causes denitrification, converting nitrates to free N2.

Q68

The product(s) of reaction catalyzed by nitrogenase in root nodules of leguminous plants is/are

A Nitrate alone

B Ammonia and oxygen

C Ammonia and hydrogen

D Ammonia alone

Correct Answer

Option C

Solution

(c) Nitrogenase: N2 + 8e- + 8H+ + 16ATP → 2NH3 + H2 + 16ADP + 16Pi.

Q69

A free living nitrogen-fixing cyanobacterium which can also form symbiotic association with the water fern Azolla is

A Tolypothrix

B Chlorella

C Nostoc

D Anabaena

Correct Answer

Option D

Solution

(d) The freshwater fern Azolla harbours Anabaena (a blue green alga) in its leaf cavities.

Chlorella is simply a green alga.

Nostoc is a free living cyanobacteria involved in $N_2$ fixation and so is Tolypothrix.

Q70

Nitrogen fixation in root nodules of Alnus is brought about by:

A Bradyrhizobium

B Clostridium

C Frankia

D Azorhizobium

Correct Answer

Option C

Solution

(c) Nitrogen fixation in root nodules of Alnus is brought about by Frankia.

It is a symbiotic nitrogen fixing bacteria in root nodules of several non-legume plants like Casuarina (Australian Pine), Myrica and Alnus (Alder).