Test: Mechanism of Absorption of Elements (Old NCERT) - Grade 11 MCQ

Nitrogenases are enzymes that are produced by certain bacteria, such as cyanobacteria (blue-green algae).
These enzymes are responsible for the reduction of nitrogen (N₂) to ammonia (NH₃).

Insectivorous plants are carnivorous plants that feed on insects.
These plants have adapted to grow in the extreme conditions of the soil such as acidic pH. Generally, these plants are known to grow in the soil which is deficient in mineral nutrients due to the presence of acid.
The plant can grow in soil that has low levels of nitrogen.

The phosphate groups allow the nucleotides to link together, creating the sugar-phosphate backbone of the nucleic acid while the nitrogenous bases provide the letters of the genetic alphabet.
These components of nucleic acids are constructed from five elements:
carbon, hydrogen, oxygen, nitrogen, and phosphorous.

Molybdenum, as well as Phosphorous, play important role in Biological Nitrogen Fixation.
Nitrogen fixation needs an enzyme called nitrogenase. The nitrogenase enzyme has two kinds of proteins viz. Iron Protein, and Iron-Molybdenum protein. 

Ozone (O₃) is an isotope of oxygen that exists in the so-called ozone layer at a height of about 15-60 km in the middle and upper stratosphere and lower mesosphere.
This ozone layer absorbs UV-rays of longer wavelengths and protects life on Earth from the damaging effects of these radiations.
Ozone in the lower atmosphere (troposphere) is regarded as a pollutant.

Several species of Glomus, including G. aggregatum, are cultured and sold as mycorrhizal inoculant for agricultural soils. Being endomycorrhiza, it helps the plants in the absorption of nutrients especially phosphorus from soil. 

Nitrosomonas convert ammonia into nitrates by a process called nitrification.
It is performed in two steps: 
(i) Nitrite formation
(ii) Nitrate formation

Denitrification is carried out by a large variety of heterotrophic bacteria, the most common ones thought to be Clostridium, Pseudomonas and Bacillus.

• Leghemoglobin supports the centralization of free oxygen in the cytoplasm of contaminated plant cells to guarantee the best possible capacity of root knobs.
• Its capacity is to help give oxygen to the breathing harmonious bacterial cells in root nodules of leguminous plants in a way practically equivalent to hemoglobin transporting oxygen to breathing tissues in creatures.

The nitrification process requires the mediation of two distinct groups:
(i) Bacteria that convert ammonia to nitrites (Nitrosomonas, Nitrosospira, Nitrosococcus, and Nitrosolobus)
(ii) Bacteria that convert nitrites (toxic to plants) to nitrates (Nitrobacter, Nitrospina, and Nitrococcus).