Question

A red pigment in the root nodules of leguminous plants is known as
(A) Phycoerythrin
(B) Bacteriochlorophyll
(C) Leghaemoglobin
(D) Bacterioviridin

Answer 1

Hint: A red pigment is mostly presented in the root nodules of the leguminous plants which function as oxygen carrier. This pigment is similar to the oxygen carrier found in human blood. The presence of this pigment helps in establishing good coordination between the host and the bacterium present in the root nodules.

Complete answer:
To answer this question, we must know about the root structure in leguminous plants. The leguminous plants are associated with the nitrogen-fixing bacteria such as rhizobium through symbiosis. The rhizobium attacks the root hairs of the leguminous plants and appears as root nodules where nitrogen fixation occurs.

Usually, the symbiotic associations amongst plants and bacterium lead to the production of leghaemoglobin. The leghaemoglobin plays a crucial role as it restricts the denaturation of the nitrogenase enzyme, if it comes in contact with the atmospheric oxygen. It also applies sufficient quantities of oxygen to the bacteria, essential for its respiration.

Phycoerythrin- It is a red coloured photosynthetic pigment which is found in red algae and cyanobacteria.

Bacteriochlorophyll- It is a photosynthetic pigment present in plants, algae and cyanobacteria. It absorbs red and far-red light.

Bacterioviridin- It is also known as chlorobium chlorophyll. It is found in purple sulphur and non-sulphur bacteria.

Hence the correct answer is option ‘C’.

Note: The chemical arrangements of leghemoglobin that is iron bound to heme protein. The leghaemoglobin efficiently assists the supply of oxygen to the bacterium. Generally, the leghaemoglobin is a monomeric protein which is structurally alike as that of the myoglobin and haemoglobin.